Deinocheirus: why beer-bellies are bad-ass and the importance of being weird

Today started out as a fairly normal day. I overslept thanks to marathonning House late into the night/morning (note: not due to working late/early on my publication, oops), I dragged myself out of bed and into the office. I then, still half-asleep checked Twitter (the morning ritual was well underway) and then suddenly, I displayed both ends of the NedryGrant excitement chart (patent pending) simultaneously. Deinocheirus. It was DeinocheirusDEINO-RUDDY-CHEIRUS! At the moment, I’m in an office full of volcanologists, so no-one understood my excitement (in fact most thought I had some form of disposition, I mean I was practically frothing at the mouth with excitement). I immediately texted Richard and all my other palaeontological friends/colleagues with two words: DEINOCHEIRUS PUBLISHED.

My face on the morning of the 22nd October 2014. (I even laughed like a Dilophosaurus).

Story time

So why was I so stupidly excited? Well, I’m glad you asked. To explain this excitement, our tale begins in 1965. It was July, and the Polish-Mongolian Palaeontological Expedition had stumbled upon a ‘monster’ find. Forelimbs and a shoulder girdle 2.4 metres long belonging to a 70 million-year-old dinosaur with surely the largest forearms of a bipedal animal ever. However, that was all they found. What in the Seven Hells was this magnificent beast? Surely these the arms of some superpredator, akin to Allosaurus or perhaps a mega-Velociraptor? Deinocheirus mirificus was (‘unusual horrible hand’) was ‘born’. For seven-years, this was the most likely explanation. In this time, palaeontologists and members of the public alike went wild with fantastical recontructions of this new and wacky beast, some even going as far as noting that the arms were used much like those of a giant sloth. Alas, in 1972 John Ostrom (the guy responsible for revolutionising the way we think about dinosaurs in relation to birds in the 60s) noted that the bones in the forearm of Deinocheirus appeared similar to those found in the ornithomimosaurs, a group of secondarily-herbiverous theropod dinosaurs very similar to modern ostriches. This agreed with the sentiments of the team that initially discovered Deinocheirus, so it was settled, the beast was in fact an ornithomimosaur. Mystery solved. Right?

Dem Claws.

Dem Claws.

Unfortunately not. Fast forward a little over 40 years later to October 2013, and we still hadn’t found any more remains of the all-too mysterious Deinocheirus. That was all to change. At the SVP 2013 Symposium (one of the biggest annual events in palaeontology) there were hushed, exciting whisperings of new Deinocheirus material (apparently, I couldn’t afford to go). And then, a speaker emerged and confirmed it, Deinocheirus was back, the mystery was apparently solved. New material had been discovered and we now had a 95% complete skeleton to work with. However, this wasn’t fully shown at SVP, and the entire palaeontological community had to wait with baited breath until the work was published. One of the greatest mysteries of 20th and 21st century dinosaur palaeontology had been solved, but we had to wait. It was agonising. Personally, I grew up enthralled with the mystery of Deinocheirus as did many palaeontologists, both young and old, so to be kept in the dark like this was painful.

The Big Reveal

Fast forward again, exactly (pretty much) to a year later. Late October 2014. A dreary-eyed, 20-something-year-old palaeo grad-student is almost hyperventilating over an image he found on Twitter. Ladies and gentlemen, Deinocheirus has landed. And bloody hell if it isn’t the weirdest thing we’ve ever seen.

Deinocheirus-990x980

The Beer-Bellied weirdo in all it’s glory. Deinocheirus mirificus.

Mystery Solved

Standing almost as tall as T. rex, and weighing in at a hefty 6 tonnes Deinocheirus is the biggest ornithomimosaur to dateSo it was big, no biggie right (heh)? Wrong, in addition to it’s monstrous size it’s also (and I might have already said this) bloody weird. With a really deep lower jaw, no teeth, huge forearms, relatively small hindlimbs, a big old “beer belly” (the best description of dinosaur’s anatomy ever, thanks Tom Holtz!) and tall neural spines (similar to those seen in SpinosaurusDeinocheirus sure is different to the ‘typical’ ornithomimosaurian body plan of Galimimus, with long legs and many other features that suggested it was a fast runner. Quite the opposite, Deinocheirus was a big, sluggish brute with a huge appetite. After 50 years, the mystery of Deinocheirus seems to be solved then, it’s a incredibly odd looking, slow moving, bulky, T. rex sized, beer-bellied behemoth. Myth busted, right?

Skeletal reconstruction of Deinocheirus mirificus. Modified from Lee et al. 2014.

Skeletal reconstruction of Deinocheirus mirificus. Modified from Lee et al. 2014.

Again, wrong. These new specimens are that good that we can already begin to hypothesise how Deinocheirus actually lived out it’s seemingly odd, slow lifestyle. Deinocheirus was discovered in the Nemegt Formation, a deposit which is 70 Million years-old (Late Cretaceous), and was an ecosystem similar to that of the Okavango delta today. First off, over 1400 gastroliths were present, probably used to aid in digestion of food, (mainly plants) making up for the lack of teeth. The morphology of it’s jaws and its broad bill (similar to those found in hadrosaurs and ducks) suggest that certain muscles associated with biting were small, meaning that Deinocheirus probably ate soft (and possibly water-dwelling) plants. But there wasn’t just some stones in that big beer belly, no sir! Evidence of a half-eaten fish was found as well, indicating that Deinocheirus was no means a fussy eater, and probably a ‘megaomnivore’ eating pretty much anything it could get it could swallow. This seems to fit well, especially when you consider Deinocheirus’ place in the Nemegt ecosystem, as generalist ‘all you can eat’ type deal (finally, a dinosaur I can relate to) it wouldn’t be in such harsh competition with the other herbiverous dinosaurs in the area that mostly ate plant matter from trees. However, not only do you need to outcompete you friendly neighborhood herbivores to keep on truckin’ in a Cretaceous world, you also need to be not eaten yourself. The main threat in the Nemegt ecosystem was probably the 12 metre long, 5 ton tyrannosaur, Tarbosaurus. However, Deinocheirus seemingly has an answer to everything by sacrificing speed for bulk and size, it was probably too big (and bloody hell, those claws) for Tarbosaurus to safely take on.

Deinocheirus_fin_colcorr_lres

Deinocheirus in situ. Image credit: Andrey Atuchin.

We also know a few more tricks that Deinocheirus had up its exceedingly large sleeves. Remember those Spinosaurus-like neural spines? They were probably there to support the bulky beer belly, similar to an “asymmetrical cable-stayed bridge“. It also had broadended tip-toes (pedal unguals, to be technical), allowing it not to sink when wading into wetter areas. And those claws? No longer used as lethal disembowlers, but for digging/plant gathering. So Deinocheirus seemingly was perfectly adapted to life on the braided, meandering rivers of the Nemegt ecosystem, unafraid of pesky Tarbosaurus, perfectly content to munch away until its heart (and beer belly) was content, and then waddling to the next patch of river to devour (and P.S Deinocheirus didn’t half walk funny).

And the moral of the story is…

By now, you’ve probably found literally hundreds of grammatical and spelling errors, due to the fact that I’ve been excitedly vomiting words onto my laptop in wave after wave of dino-induced mania. Yes it’s weird, and yes I love it because it’s pretty much me in dinosaur form, but why is this important? You’ll probably see this on IFLS (I F***ing Love Science) in a summary post, with ‘weird fat dinosaur discovered’ alongside ‘cure for cancer found’ and ‘artificial intelligence finally sorted’, making palaeontology, yet again look like the stupid and childish sibling of all the other sciences (e.g. “dino with big nose discovered”, unfortunately not a joke). But this is more than just some crazy guys with beards and stetsons finding a random pile of bones and shouting eureka until Nature finally publishes their work. Oh no. This, as well as many other finds over the last year shows us just how extreme dinosaurs can get. In the past 12 months, we’ve had a new, now with more swimming (TM) Spinosaurus recontruction, Dreadnoughtus, possibly the largest dinosaur ever, as well as long-snouted and pygmy tyrannosaurs. Not to mention feathered ornithischians (R). Dinosaurs have often been regarded as evolutionary extremes, and we’re only now beginning to understand just how these extreme animals lived and evolved.This understanding allows us to further understand evolution works, and how organisms can evolve in various environments and under different conditions.Not only is Deinocheirus a weird and wonderful beast, but when we look at it as a living, breathing animal, rather than a poster-child for all things weird and wonderful, we can begin to further understand  the evolutionary processes involved in theropods, a group which would garner the evolution of an incredibly diverse and successful group of animals, the birds. Deinocheirus exemplifies that palaeontologists, by investigating extremely adapted animals, such as dinosaurs, can further the understanding of the the process of evolution, one of the most important processes on Earth, and just how far it can go, and what wonderfully strange creatures it can help to explain.

So there you have it. Deinocheirus. It sure is a good day to be a palaeontologist.

Dino Sirs on Tour: Prog Pal 2014, Part 1 (Ryan).

Since the schedule for conferences is jam-packed (and then when the day’s over, everyone is in the pub until people stagger back to hotel rooms), Richard and I could barely take the time just to keep you updated on Twitter during Progressive Palaeontology 2014. However, we’d thought we’d share our experiences (as this our first proper palaeontological conference) and hand out some tips for anyone out there whose thinking about going to a conference any time soon. Anyway, first off, I’ll (Ryan) give my accounts of ProgPal 2014.

Progressive Palaeontology (just Prog Pal to most) is an annual symposium/conference/get-together/piss-up where palaeontologists early in their career (predominately PhD and Masters students, with some keen undergraduates) come together and present their work. It’s a fairly small event, with around 100 people in attendance and lasting only a day. This makes it a perfect introductory conference, with a laid-back atmosphere that isn’t quite as scary as SVP or Pal Ass. Anyway, here comes the blow-by-blow account of my Prog Pal 2014 experience..

Tip #1: Preparation is the key to success. Aside from an opportunity to see what other palaeontologists are up to, conferences are about networking, and getting yourself ‘out there’. Some time before the conference starts, you’ll be sent a list of abstracts of all the people presenting, as well as a list of all the people in attendance. Check through this list and see if there’s any names that you’d like to work with, and plan all the people you want to shake hands with before you get there.

05:30: Christ it’s early. Christ I’m hungover. Richard and I decided we’d drink fairly heavily after the induction and icebreaker session. Big mistake, as I’ve got to give a talk today, my first ever talk at a conference. I wake up and can’t get back to sleep, so quietly practice my talk over and over.

06:42: Richard finally decides to stop snoring and wake up. Lazy so and so.

Tip #2: DON’T DRINK TOO MUCH THE NIGHT BEFORE THE CONFERENCE.

08:15: Richard and I are at the closest Wetherspoons (pub) to the National Oceanographic Centre (where Prog Pal was held this year), and our hangovers are subsiding after a hearty (and well priced) breakfast. With excitement and glee (as well as the grease from the breakfast) in our hearts, we set off to the NOC.

08:45: We arrive at the NOC and put up our posters. We’re a little late to the proceedings (like the rebels we are), so our posters are right at the far end. Great.

Tip #3: If you’re present a poster, put it up ASAP. Remember, you want the prime real estate so more people have the chance to see the work you’ve spent months slaving away on…

08:46: I impulse buy a Temnodontosaurus PalaeoPlushie. SO CUTE. (And accurate!)

09:00: Jon Tennant himself kicks of the talks of Prog Pal 2014 with a phylogeny of dwarves. No seriously, actual dwarves. (And then talks for a bit about atoposaurids).

Slightly disappointed when I realised the talk was on atoposaurids rather than actual dwarves.

Slightly disappointed when I realised the talk was on atoposaurids rather than actual dwarves.

09:51: Mid-way through one of my supervisors’ (Ben Moon) talk (on the phylogeny of ichthyosaurs) I have a “oh s**t” moment as I realise his data makes the published phylogeny I used in my analyses obsolete. Welp, back to the drawing board on that hypotheses.

10:30: Coffee break time! It’s also the start of the first poster session, so Richard and I eagerly away the throngs of people who love ichthyosaurs and stem-gnathostome evolution.

10:31-10:50: Richard and I get a grand total of 2 people each looking at our posters, whilst the throngs of people congregate at the other end of the conference hall…

Richard and I next to our posters. The person who photographed us here accounted for probably a quarter of the people who looked at our posters all day...

Richard and I next to our posters. The person who photographed us here accounted for probably a quarter of the people who looked at our posters all day…

Tip #3: I reiterate, if you can, place your poster where most people will see it!

10:40: One of my hypotheses get’s put through the ringer by Colin Palmer (a prominent worker in the field of pterosaur flight). He presents valid points, so it’s back to drawing board on yet another hypothesis.

Tip #4: Prepare for criticism (usually constructive). Conferences are about showing your work off to other scientists, and some people may know more about certain things than you. That’s okay, it might take you down a completely different path with your study, perhaps to new and exciting work!

10:50-12:30: The second session is talks on invertebrates and early vertebrates (even Richard ‘fish and early vertebrates 4 lyfe’ Dearden finds some parts a little dull). For most of it I have know idea what’s going on. I muddle through until Robert Lemanis’ talk on ammonite shell function, which was AWESOME.

12:54: Over lunch, Richard learns that he missed out on meeting Philippe Janvier (as he came to Prog Pal rather than go to the Woodward Symposium). For pretty much all of lunch he lets me know how he’ll never forgive himself.

13:25: Richard’s still going on about Philipe bloody Janvier.

13:30: Luckily, the third talk session starts, so Richard gets away unharmed.

Tip #5: Never mention Philippe Janvier in the presence of Richard.

14:15 PM: Sam Giles gives an absolutely wonderful talk on an exceptionally preserved actinopterygian skull from the Devonian. She really knows how to give a talk, and she presented some awesome CT data!

15:00-15:20: Another poster session. Robert Lemanis and I chat away about CT resolutions. (And I heartily congratulate him on making ammonites really cool).

15:20-16:53: Over the next hour and a half I was too nervous to remember anything, as my talk was coming up. Jon Tennant sends me an amusing Tweet.

Fairly sure this is Jon Tennant's favourite meme ever.

Fairly sure this is Jon Tennant’s favourite meme ever.

16:53: I give my talk, and the nerves get the better of me. I have some form of brainfart and stutter over the same point for what felt like an eternity. Somehow I get back on track and finish on time. Phew. I’m still in a foul mood for an hour or so.

Tip #6: Never let the nerves get the better of you. Yes it’s much easier said than done, but at the end of the day, you’re giving a speech about something that you probably know more about than anyone in the world, so you have a right to be there and ace it.

Yours truly about to give a talk. I didn't have butterflies, I had azhdarchid pterosaurs in my stomach...

Yours truly about to give a talk. I didn’t have butterflies, I had azhdarchid pterosaurs in my stomach…

17:40: Audrey Roberts chats to me whilst I’m posted by my poster. We chat for a while about ichthyosaurs. It was great to meet another ichthyosaur worker!

18:00: It’s over, the posters are taken down and we head on over to the Royal Thai Pier to begin the evening’s festivities.

18:04: We realise it’s absolute pissing it down and spend the next 15 minutes walking gloomily.

18:19: Fear not! We arrived at the restaurant and chowed down on some tasty (and much too hot for Richard’s liking) food. Winners of the day are announced, and it was great to see so many Bristol students (and alumni) take home prizes! Wine is consumed.

20:25: Richard’s supervisor buys him a drink, I look over to my supervisor in a desperate attempt to get a free beverage. No chance.

Richard looking pleased with himself after eating something hotter than a fish finger sandwich. Our friend, Amy, looking miserable as always.

Richard looking pleased with himself after eating something hotter than a fish finger sandwich. Our friend, Amy, looking miserable as always.

21:00: We’ve made it to the same Wetherspoons as last night, we feel like we’re home at last.

21:01-22:00: I hang out with the Bristol MSc cohort, and we all drink far too much. Although not as much as Richard’s supervisor, who’s still buying Richard drinks. No sign of Ben buying me a drink.

22:30: Richard (now fairly drunk) announces we should mingle. So we stand up, and immediately take drunk selfies for a bit.

Tip #7: Make sure either a) they can’t see you or b) that the people you planned to network with you at the conference are drunk enough to forgive you taking selfies. Or just ask them to join in.

Tip #8: On a more serious note, the pub is great way to network in an informal setting, if you don’t get the time to speak to people during the conference.

23:04: Ben Moon reveals to me with wry smile he probably should have given me his phylogeny a while back. No kidding. Still, it gives me something to look at over the summer.

23:10: Jon Tennant tells me he voted for my talk, saying my work was ‘progressive’ and ‘cool’. Somewhat tipsy, it was hard not to straight up hug the guy.

23:30: I watch a fellow MSc student hilariously try and get 4th authorship on Richard’s future paper, despite doing absolutely nothing. Unfortunately, Richard’s having none of it.

23:35: Richard brings up Janvier again and I seriously consider glassing him.

23:50: Last orders, Richard and I stay classy and order two double G&T’s.

00:00: We set off back to the hotel, fairly inebriated.

The last photo I took at Prog Pal 2014. A selfie (of course). We were sober, honest.

The last photo I took at Prog Pal 2014. A selfie (of course). We were sober, honest.

And their we have it ladies and gentlemen, Progressive Palaeontology 2014. Unfortunately, I wasn’t able to attend the field trip to the Isle of Wight the next day, as I had to give a talk back in Bristol. I had great fun, and I’d like to take this opportunity to thank everyone who made Prog Pal possible this year, you guys did a wonderful job of organising the whole thing. Finally, I just like to summarise a few things about conferences:

  • Always prepare who you want to network is, as my Nan often says (and it really does apply to the academic world) “it’s not what you know, it’s who you know”, so it’s vital that you take every opportunity to meet and greet people that you’re interested in working with.
  • Be prepared for constructive criticism. It’s a huge part of the academic process (and it always hurts a little bit more in person).
  • If your presenting a poster, think about where abouts in the conference hall you’ll be located (if you get the choice).
  • If your giving a presentation, don’t let nerves get the best of you, and remember that you know your stuff, otherwise you wouldn’t be there!
  • Most of all, have fun, it’s so invigorating to spend time with lots of people who are passionate about the same kind of things you are.

Stay tuned for Richards account of Prog Pal (and prepare to read about Philippe Janvier…) over the next few days.

What’s New(s): 11/04/2014

Avid readers of TDS, we have again not published as often as we’d have liked to over the last few weeks, as deadlines are piling up over here in TDS Towers. Fear not, as below is a bountiful harvest of palaeontological news, five of the most succulent morsels, handpicked by Richard and I, for your entertainment.

Embry-old

Fossilised creatures generally, even those as big as dinosaurs are pretty rare. The forces of nature and preservation all stack up against palaeontologists when we try and find fossils. So when very small fossilised early stage embryos from over 500-million-years-ago are found, it certainly doesn’t go unnoticed. Whilst not new to science, the latest publication of fossil embryo’s gives some much needed insight into how such small and delicate structures were fossilised. Researchers from Missouri and Virginia Tech have found fossilised embryos in the Shuijingtuo Formation (China) which are around 500 million years-old (from the Cambrian period). Despite not being the oldest fossilised embryos (the fossil record of embryos stretches back beyond 580 Mya in the Doushantuo Formation, Pre-Cambrian), the Shuijingtuo embryos contain the soft tissue impressions of the chorion (the fertilisation envelope). The authors also suggest that in this fossil deposit, the preservation of these soft tissues is more common due to these tissues being (somehow) selectively phosphatized. At this point, how these small and rare embryos got to be preserved is all that is known of the Shuijingtuo embryos, but future discoveries on what organisms these embryos belonged to, or even better preserved embryonic soft tissues will prove to be very exciting reads in the months and years to come.

Whilst not the embryos in question, they have caused a massive stir over the years.

Ancient ‘Sp-eye-ders’ from M(ontce)A(u-les-Mines Lage)RS(tätte)

I’m (Ryan) a huge arachnophobe. So I wasn’t best pleased when Richard brought this (albeit interesting) tidbit of news to my attention. A new extinct species of harvestman from the Carboniferous, Hastocularis argus, was recently discovered in France which has allowed the authors to comment on the evolution of the group. It’s also thrown up some eye-opening surprises. Before I continue on the subject, the jovial title of this story is wrong. Whilst harvestmen are arachnids, they aren’t spiders, they’re actually more closely related to mites. Regardless, the discovery of H. argus has allowed Garwood et al. to investigate the origins of harvestmen more closely, as the exoskeletons of these arachnids are rarely preserved in the fossil record. With the creation of a new mite suborder, Tetrophthalmi (which includes H. argus and the Devonian species, Eophalangium sheari), Garwood et al. have, contrary to previous beliefs, argued that the diversification of modern harvestmen occured later in geological time (Carboniferous, rather than Devonian).

The (albeit not so scary looking) Hastocularis argus rendered in full 3D glory.

The (albeit not so scary looking) Hastocularis argus rendered in full 3D glory.

Modern harvestmen have just a single set of eyes, the medial pair (central). However, the 305-million-year-old H. argus has two pairs of eyes, a medial and a lateral (outer) pair. In the same paper, Garwood et al. report that work on modern harvestmen has revealed that despite the passage of over 300 million years, they still retain some genetic framework for these lost lateral eyes. This paper (despite being on arachnids *shudders*) is pretty great, as it combines modern 3D visualisation techniques (CT scanning), phylogenetics and some genetic work in order to really get a handle on the origins of a previously poorly known group. This again proves that the combination of palaeontology and biology is a real ‘dream team’ when it comes to unearthing evolutionary relationships.

 Cambrian heart-thropod’s gets palaeontologists’ blood pumping

I genuinely rewarded myself with a break after making that title, the puns have (if I do say so myself) been exceptional this week. Regardless, a fascinating insight into the evolution of the cardiovascular system has been published in Nature Communications this week (7th April). An exceptional specimen of Fuxianhuia protensa, a 520-million-year-old arthropod from Chenjiang deposits has been described, and with a cardovascular system almost intact. Even though the phylogenetic placement of Fuxianhuia is controversial to say the least, in 2012 it was discovered that Fuxianhuia had a relatively complex brain, suggesting by the early Cambrian, arthropods already had similar visual capabilities as modern insects.

 

Fuxianhuia reconstruction from Ma et al. (2014). a) cardiovascular system and CNS; b) whole body reconstruction; c) cardiovascular system in relation to the gut.

Fuxianhuia reconstruction from Ma et al. (2014). a) cardiovascular system and CNS; b) whole body reconstruction; c) cardiovascular system in relation to the gut.

Perhaps it is a tad unsurprising that this latest Fuxianhuia discovery reveals that the cardiovascular system of arthropods from the early Cambrian were relatively advanced, and more than able to keep the ‘complex’ brain oxygenated with blood. The combination of an advanced cardiovascular and neural/visual system has led Ma et al. to conclude that F. protensa had well developed sensory (using vision and its antennae) system, and in life it was a highly mobile forager. They also conclude that even by the Cambrian Explosion, arthropods had evolved many advanced biological systems.

Teenage Mutant Ninja Hupehsuchians, swimming in a half shell.

Because what would a blog post on TDS be without a marine reptile? (Also, it’s taken until the 4th news piece to get to a tetrapod, what is this nonsense?). Moving on swiftly, the next discovery presents a new species of marine reptile, Parahupehsuchus longus. After taking a quick look at the holotype of P. longus (pictured below) you’d be very much forgiven if you thought it was an early Triassic ichthyosaur. P. longus is in fact a hupehsuchian, which a group of diapsid reptiles from around 250 Ma, and are known exclusively from one locality, in Hubei Province (China).

An incredibly dumb looking hupehsuchian, Nanchangosaurus (a close relative to Parahupehsuchus).

An incredibly dumb looking hupehsuchian, Nanchangosaurus (a close relative to Parahupehsuchus).

So what makes Parahupehsuchus so cool? Well in its defenceP. longus has a weird expansion of its ribs (similar to the ribs of turtles, that’s how they ‘make’ their carapace) which overlap to form a ‘bony tube’. As indicated by the aforementioned pun, Chen et al. think that this is used as a defence mechanism. Whilst the fact that the same kind of defence mechanism (revolving around the expansion of the ribs) has convergently evolved in at least 2 groups of marine diapsids is fairly interesting, it’s the wider implications of this discovery that really make Parahupehsuchus cool. What does any creature needs a defence mechanism for? That’s right Captain Obvious, defence. This almost definitely means that during the early Triassic, there were large predators and a higher trophic level was present at this time. This is odd, you wouldn’t expect this trophic level to recover so quickly after the Permo-Triassic extinction event (commonly referred to as ‘when life nearly died’, so you know, it’s pretty potent). Chen et al. make 2 pretty bold claims from this one discovery, stating that the recovery from the event was faster in the marine realm (specifically faster in marine predators) and that this marine tetrapod predator trophic level is probably the first one ever to emerge in evolutionary history.

Bird’s and pterosaurs had to Cope with one another

Cope’s rule, simply put is a hypothesis that states evolutionary lineages, over time, increase in size. Pterosaurs have long been the poster child of Cope’s rule in the fossil record (along with horses) going from small rhamphorhynchids in the late Triassic to the huge (and probably flightless) azhdarchids of the Cretaceous. The study by Benson et al. set out to try and understand this apparent trend in pterosaur size evolution further. They found that up until the late Jurassic/early Cretaceous the average wingspan didn’t really go above 1m, and over the cretaceous there was a sustained increase in wingspan, until you reach the monstrous 10m+ wingspans of azhdarchids such as Quetzacoatlus northropus.

Obligatory funny, only very slightly related picture.

Obligatory funny, only very slightly related picture.

A controversial notion that it was the emergence and radiation of the (somewhat smaller) birds in the late Jurassic/early Cretaceous that drove the evolution of large size in pterosaurs. In a unexpected turn of events, Benson et al. actually suggest that this may well be the case, citing a possible combination of ‘intrinsic factors’ (such as terrestrial living in azhdarchids and other flight mechanisms in other groups) and ‘extrinsic factors’ (such the evolution of birds, which would have taken the niches occupied by small aerial feeders away from the pterosaurs) as the cause of the switch to selection of a larger body size in pterosaurs. It just goes to show that competition can be, in some cases, used to explain macroevolutionary processes and patterns.

References

Brose, J. et al.  (2014) Possible Animal Embryos from the Lower Cambrian (Stage 3) Shuijingtuo Formation, Hubei Province, South China. Journal of Paleontology: March 2014, Vol. 88, No. 2, pp. 385-394.

Garwood, R. J. et al. (2014). A Paleozoic Stem Group to Mite Harvestman Revealed through Integration of Phylogenetics and Development. Current Biology, http://dx.doi.org/10.1016/j.cub.2014.03.039.

Ma, X. et al. (2014). An exceptionally preserved arthropod cardiovascular system from the early Cambrian. Nature Communications 5, 3560, doi:10.1038/ncomms4560.

Chen X-h, et al. (2014) A Carapace-Like Bony ‘Body Tube’ in an Early Triassic Marine Reptile and the Onset of Marine Tetrapod Predation. PLoS ONE 9(4): e94396. doi:10.1371/journal.pone.0094396

Benson et al. (2014). Competition and constraint drove Cope’s rule in the evolution of giant flying reptiles. Nature Communications 5, 3567, doi:10.1038/ncomms4567.

What’s new(s): 22/03/14

We’ve got a range of stories for you in this week’s What’s News including evolving cetaceans, pygmy dinosaurs, and aquatic ground sloths.

A long-mandibled porpoise

Cetaceans are fairly weird animals to begin with: secondarily aquatic even-toed ungulates (like cows and sheep) that are grouped with hippos in the colourfully-named group, the Whippomorpha.  They’ve lost their back legs, have adapted their front ones to form flippers, and have developed dorsal and tail fins, and this morphology has proved extremely successful as they have radiated to fill many niches in the oceans, including filter feeding, suction feeding and giant squid eating.  A new fossil porpoise has recently been described from the Pliocene of California that adds to this diverse array of morphologies with it’s bizarrely shaped lower jaw.  The lower jaw of Semirostrum cerutti extends well past its upper jaw to form a prognathous projection, which was apparently well nourished by arteries.  This morphology is most similar to the mandibular morphology of skimmer birds, which fly low and close to the water while using their long and highly sensitive lower beaks to probe for underwater prey.  The authors argue that the properties of Semirostrum’s mandible suggest it did a similar thing in sediment at the bottom of the sea.

skimmer porpoise

A reconstruction of a ‘skimming’ Semirostrum and his joyous friend.  (From Racitot et al)

Evolving echolocation

Continuing on the whale-y theme, modern whales are split into two groups: the Odontoceti, or toothed whales, and the Mysticeti, or baleen whales.  The baleen whales filter feed small animals with their baleen, while the toothed whales (which include Semirostrum, who we just met) use echolocation to locate their larger prey, which involves emitting calls and listening to their echoes like a sort of biological sonar. These echolocating  vocalisations are associated with a unique array of features in odontocete skulls, that serve to amplify and  receive the sound.  The newly described Oligocene whale fossil Cotylocara macei is argued to possess these features, including dense snout bones argued to act as an acoustic reflector and a lot of room for the anchoring of a muscle associated with echolocation, the maxillonasolabialis (yep, apparently that’s a thing).  This brings the evolution of echolocation firmly down the odontocete stem, meaning that it evolved shortly after they diverged from mysticetes about 34-30 million years ago.

Whale phylo

If Cotylodira did echolocate, it suggests an origin where the arrow is pointing.  From Geisler et al.

Swimming sloths

As well as the familiar cetaceans, many other mammal groups have famously made the move to an aquatic life including manatees, seals and otters.  Common adaptations to this aquatic life are pachyostosis, the swelling of the solid outside layer of bone, and osteoschlerosis, the densification of bone, adaptations which are both argued to have evolved to reduce the animals buoyancy.   Were you to visit the Miocene-Plocene of Peru you might meet a less well-known aquatic mammal with these adaptations: the ground sloth genus, Thalassocnus.  While modern sloths seem happy to go for the occasional swim, this animal was adapted to an underwater life, and probably fed on marine vegetation.  A number of species of Thalassocnus existed throughout time, and Amson et al studied slices of their bones to track the evolution of pachyostosis and osteoschlerosis.  They found it could be tracked through the successive species as they increasingly adapted to aquatic life, offering a rare high-resolution view of the evolution of a trait, as well as further proof that sloths are awesome.

sloth bones

The ribs of Thalassocnus plotted onto a phylogeny, becoming denser as the genera adapted to marine life. The fact I put up this and resisted the urge to post one of the internet’s many sloth pictures is a testament to my dedication to palaeobiology and to you, dear reader. From Amson et al.

Pygmy Tyrannosaur

Another thing that’s awesome is, of course, dinosaurs, and we have two dinosaurs for your delectation and delight this week.  The first of these is a tyrannosaur, Nanuqsaurus hoglundi, the generic name (Nanuqsaurus) of which means ‘polar bear lizard’, surely one of the cooler (pun obvs intended) dinosaurian names.  This tyrannosaur was described last week from material found in Alaska, and defies the popular perception of tyrannosaurs as enormous carnivores by being relatively small.   As well as adding to our understanding of tyrannosaur diversity, this is particularly interesting as Alaskan members of another dinosaur genus, Troodon were found to be about 50% larger than their more southerly counterparts.  This was originally argued to be due to Troodon’s characteristically large eyes giving it a competitive advantage over other theropods in the low light conditions of the Arctic, selecting for larger body size.  The fact that Alaskan tyrannosaurs are, conversely, smaller is argued by the authors to add weight to this idea, with the claim that the opposite situation applied due to their diminished ability to see: a lowered competitive advantage resulted in selection for reduced size.

Pygmy

Size of Nanuqsaurus (A) compared to other tyrannosaurs (B-E, T. rex is B).  ‘Normal’ Troodon is F, with Alaskan Troodon as G.  From Fiorillo and Tykoski.

The ‘chicken from hell’

You’ve probably already heard of the second dinosaur that we encounter this week, the ‘chicken from hell’, Anzu wyliei.  Given that the generic name of the taxon is taken from an ancient Mesopotamian feathered demon (tbh, probably trumping polar bear lizard) one might question why it needs to be described as a ‘chicken from hell’, but hey ho.  Anzu is a new, and the most complete, member of the Caenagnathidae, members of the oviraptorsaurs like the more familiar Oviraptor. The Caenagnathidae contains taxa such as the massive Gigantoraptor, but so far is poorly known; Anzu goes some way to solving its relationships.   Like many other oviraptorsaurs it had a large, cassowary-like crest and no teeth; much debate has been had over exactly what dietary niche this group inhabited, and no firm answer has yet been reached.  Whatever its exact niche, Anzu is about 67million years old, and so it dates from immediately prior to the K/T mass extinction, and was found in the famous Hell’s Creek formation, showing that this locality still has information, and dinosaurs, to offer.

Screen Shot 2014-03-22 at 17.06.24

Anzu’s skeleton reconstructed. From Lamanna et al.

References

  • Racicot et al (2014) Unique feeding morphology in a new prognathous extinct porpoise from the Pliocene of California, Current Biology
  • Geisler et al (2014) A new fossil species supports an early origin for toothed whale echolocation, Nature
  • Amson et al (2014) Gradual adaptation of bone structure to aquatic lifestyle in extinct sloths from Peru, Proc. Roy. Soc. B
  • Fiorillo and Tykoski (2014) A diminutive new tyrannosaur from the top of the world, PLOS One
  • Lamanna et al (2014) A new large-bodied oviraptorsaurian theropod dinosaur from the latest Cretaceous of Western North America, PLOS One

Taxon of the Week: Koumpiodontosuchus

Dear reader, don’t be put off by such a name, nor by the fact that poor little Koumpiodontosuchus has been dwarfed by Nanuqsaurus, the recently descovered ‘pygmy’ tyrannosaur (more on that when Richard finishes the latest What’s News), because this little Cretaceous critter raises some interesting questions about eusuchian phylogeny. It’s also going to be fairly short, as Richard and I are crazy busy at the moment.

Sometime in March 2011, a lady, out with her family, discovered part of the skull of Koumpiodontosuchus, and almost immediately handed it over to Dinosaur Isle, a museum on the Isle of Wight, UK (as can be seen in my dorky picture on the about page of TDS). In a rather coincidental turn of events, some months later the second part of the skull was donated to the same museum by other denizens of the Isle of Wight. The now completed skull was then meticulously studied by Dr. Steve Sweetman et al. of the University of Portsmouth. Cut to the present day, and what we have is a new species of bernissartiid crocodile (a group that includes some of the smallest neosuchian crocs, i.e. modern crocs and their immediate ancestors) from the Early Cretaceous. Koumpiodontosuchus adds to the already diverse ecosystem we see in the Early Cretaceous of the Isle of Wight, which includes an allosaur (Neovenator), Iguanodon, Polacanthus (a thyreophoran), Eotyrannus, good old Baryonyx and a brachiosaur (as well as some azdharchid pterosaurs and mammals).

A wonderful reconstruction of early Cretaceous life on the Isle of Wight. Courtesy of Mark Witton.

A wonderful reconstruction of early Cretaceous life on the Isle of Wight. Courtesy of Mark Witton.

Estimated at only 66cm in total length, Koumpiodontosuchus aprosdokiti (roughly meaning button toothed, unexpected) is a small croc with a big name. As the name suggests, Koumpiodontosuchus has ‘button’ teeth (broad and flat) situated at the back of the jaw, with pointier teeth towards the front. This dental arrangement meant that Koumpiodontosuchus could have a good crack at both catching fish at eating hard-shelled material such as molluscs. Despite its neat arrangement of teeth, its not Koumpiodontosuchus’ crowning glory. That prize belongs to the choanae.

Koumpiodontosuchus reconstruction, again by Mark Witton. Also, casual Neovenators in the back there.

Koumpiodontosuchus reconstruction, again by Mark Witton. Also, casual Neovenators in the back there.

In crocodiles, the choanae are found in the upper jaw and form the internal nostril openings (holes). Despite containing all the extant crocodiles and their recent common ancestors, Neosuchia has a subgroup called Eusuchia (“true” crocodiles”) in which all modern crocs are found. Now, there are many defining features that allow palaeontologists/taxonomists/biologists to distinguish eusuchians from the larger pool of neosuchians, but a big defining feature in recent years has been the placement of the choana(e) within the pterygoids, towards the back of the skull (if you’re getting a bit lost with crocodilian cranial anatomy, the Witmer/Holliday Lab 3D alligator project really does help a bunch). Bringing it back to the early Cretaceous of the Isle of Wight, Koumpiodontosuchus is a non-eusuchian neosuchian (it’s just a neosuchian, no big deal), so you’d expect it not to have its choana placed at the back of the skull, between the pterygoids. 

Holotype of Koumpiodontosuchus. Choana circled in red. Amended from Sweetman et al (2014).

Holotype of Koumpiodontosuchus. Choana circled in red. Amended from Sweetman et al (2014).

Well would you look at that, a choana at the back of the skull and between the pterygoids, now that sure is a turn out for the books. So what does this mean? Well it adds to the amassing evidence from other extinct crocs (e.g. the Madagascan Mahajangasuchus, a rather ugly looking brute from the late Cretaceous) that the placement of the choana(e) within the pterygoids, on its own, might not be a might sign from the taxonomic gods that the croc you’re looking at is a eusuchian.

TL;DR: Koumpiodontosuchus is a cool new (small and cute) croc from the early Cretaceous of the Isle of Wight who, despite its size, manages to further challenge the taxonomic rules that define key groups of crocodylomorphs. Pretty cool, even if a tad unpronounceable.

Taxon of the Week: Limusaurus

As a treat, this week’s Taxon of the Week is a dinosaur. Even better, it’s a dinosaur with very small hands. Despite it’s small hands, it’s managed to cement itself amidst a pretty sizeable debate, yes ladies and and gentle, this week’s TotW is Limusaurus inextricabilis.

The facts

Limusaurus was discovered in 2009 by Xing Xu, a Chinese palaeontologist whose seemingly always discovering a new species of dinosaur (over 30 valid species to date). At around 1.7m in length (roughly the size of a large-ish dog), Limusaurus was far from the biggest and most exciting looking new dinosaur of 2009, however, it was certainly a bit weird:

  • For starters it’s the first Asian ceratosaur ever described. Yes, you heard right a ceratosaur.
  • For your main course, it’s herbiverous.
  • To finish off with dessert, it’s got a beak.
Limusurus. Not your average ceratosaur.

Limusurus. Not your average ceratosaur.

True, whilst indeed not your average ceratosaur (or for that matter, theropod) such traits aren’t that weird in primarily carniverous clades. Within Theropoda, there’s many secondarily herbiverous taxa, incl. everyone’s favourite weirdo taxon, the therizinosaurs. Let’s also not forget the well known beaked herbiverous theropods, ornithomimosaurs. Oh, and did you know crocodylomorphs had a crack at beaks and herbivory (of course they did). Even though I keep harping on about its small hands, for frak’s sake, just take a look at alvarezsaurs (with even more pathetic arms than T. rex). So why exactly am I taking the time to blog about Limusaurus?

Mononykus trying, the meme that couldn't be due to it's preposterously pathetic forelimbs. Hastily drawn by me.

Mononykus trying, the meme that couldn’t be due to it’s preposterously pathetic forelimbs. Hastily drawn by me.

A debate as simple as 1, 2, 3

If you’re a fan of dinosaurs/palaeontology then you should be aware that birds evolved from theropod dinosaurs. News flash: this isn’t new. This notion really started to gain ground after seminal work by John Ostrom in the late 1960s/early 1970s (including that famous drawing of the ‘naked Deinonychus‘ as Richard likes to call it) who noted a lot of avian-like features in Deinonychus. On top of that, palaeontological records show multiple transitional forms between smaller theropods and birds (e.g. the ever eminent Archaeopteryx), and even some of the larger theropods show avian affinities (e.g. the cranial pneumatic sinuses found in Alioramus). Those are only a select few pieces of evidence that have made the evolutionary link between birds and theropods almost undeniable, there’s a so many more, it’s astounding (incl. inferred behaviour, such as avian sleeping positions in theropods: Xu & Norell 2004, and apparent egg brooding behaviour in Oviraptor: Norell et al. 1995). Watch the video if you need more peer reviewed proof that dinosaurs (even if they did look a bit like birds) were awesome. Try and show a little respect.

However, there’s always new discoveries that just love to get people arguing. The issue revolves around digit homology/identity. Essential, theropods (via evolution) ‘lost’ two fingers (digits) to arrive at the three-fingered hand seen in most theropods (aside from the aforementioned ‘weird taxa’, who lost more than 2). The same is true for birds. However, the debate revolves around which digits are lost, and which 3 form the fingers of the hand. In tetanurans (essentially the more advanced theropods, and by extension birds), it has long been thought that digits IV and V were lost, leaving a three-fingered hand consisting of digits I, II and III. Now, you’d expect birds, by being derived tetanurans to have this digital formula.  Well that would be nice wouldn’t it. Unfortunately the question of I,II,II or II,III,IV in modern birds has been debated for a very long time. New evidence in the mid-late 1990s from developmental and genetic studies showed us that the three digits of the avian hand actually developed from digits II, III and IV. Gasp, a spanner in the works!

This new evidence was then used (rather wrongly) to attempt to oppose the hypothesis that birds evolved from dinosaurs (Feduccia 2002). While I agree, the 90s developmental evidence from modern birds creates some novel evolutionary dynamics to investigate, it cannot be used to deny the whole host of other evidence that links dinosaurs to birds. Following on from the developmental studies, genetic studies in the early 2000s showed that during the ontogeny of some birds, the digit identity would change from the initial II,III,IV to I,II,III. This led to the occurrence of the ‘Frame Shift’ hypothesis, which suggests that certain genetic pathways associated with dinosaur/avian digit identity allow for ‘rapid’ changing of digit homology throughout dinosaurian/avian evolution (at it’s core, and that’s a very simplified summary). Not to be bogged down by detail (genetics isn’t my strong suit), developmental geneticists thought they’d cracked it, and that the change in digit identity over avian/dinosaurian evolution was likely to have been caused by these frame shifts.

Feduccia's (2002) argument in a nutshell.

Feduccia’s (2002) argument in a nutshell.

Enter Limusaurus. So, finally, we come to Limusaurus’ role in all of this. In 2009, Xu et al. looked at Limusaurus’ small hands and went “you know what, that’s a reduced digit I” (NOT ACTUAL QUOTE), which makes Limusaurus’ digit identity II, III, IV. As we discovered right at the start of this article (before the I made my lack of genetics knowledge crystal clear), Limusaurus is a ceratosaur, which isn’t a tetanuran, but a more primitive theropod, meaning that the II,III,IV digit identity may well be shared by most/all tetanurans, with Limusaurus representing an intermediate of sorts. Thus Xu et al. state that the digit identity of Limusaurus is more in favour of a slower, stepwise acquisition of the digit identity seen in advanced tetanurans, and eventually birds. But, as the famous saying goes, you know what small hands means…(small gloves?)

That’s right, a big controversy.

If you're confused (don't worry, so am I), this may help.

If you’re confused (don’t worry, so am I), this may help.

The small gloves are off

The Xu et al. (2009) caused a fairly serious debate, with authors such as Vargas et al. arguing that the digit condition seen in Limusaurus is derived, and based on developmental and genetic work that they (Vargas et al.) carried out, suggest that faster genetic shifts occurred in the evolution of birds. Xu et al. quickly responded (and quoted  Arthur Conan Doyle in a somewhat dramatic conclusion) and argued that the shift proposed by Vargas is not likely when the digit (and manus) morphology of fossil tetanurans is considered.

I’d sincerely like to end this post with a succinct conclusion, saying that the debate has, over the last few years been wrapped up. However, such large debates in palaeontology, due to the very nature of our field (i.e. everything we love is dead) are rarely fully resolved. This case is no exception. Researchers from Yale (Bever et al. 2011) and other top world universities have stated time and time again that the frame shift hypothesis is still viable in the context of avian evolution, and in a recent summary by Xu and Mackem, Xu is not so sure, saying neither hypothesis has evidence to topple the other. Not one for revelling in an unnecessarily depressing ending (*coughs* Firefly) I’ll leave you with this: yes, we can’t always find all the answers to big questions in palaeontology and evolution, but by creating a synergistic relationship between palaeontology and biology (genetics, evo devo etc.), future discoveries in both fields are sure to shed some light on even the biggest of debates.

If you’d like to read more on this subject, and weren’t put off by my murdering of the genetics side of things, then I’d highly recommend the aforementioned Xu & Mackem (2013) paper for a recent summary of the field (see references below, it’s in bold).

References

Xu, X. et al. (2009). A Jurassic ceratosaur from China helps clarify avian digit homologies. Nature 459, 940-944.

Xu, X. & Mackem, S. (2013). Tracing the Evolution of Avian Wing Digits. Current Biology 23, R538–R544 (and references therein).

Bever, G., S. et al. (2011). Finding the frame shift: digit loss, developmental variability, and the origin of the avian hand. EVOLUTION & DEVELOPMENT 13:3, 269–279.

Vargas, A.O., Wagner, G.P. & Gauthier, J.A. in Nature Proceedings (2009).

Vargas, A.O. & Wagner, G.P. Frame-shifts of digit identity in bird evolution and Cyclopamine-treated wings. Evolution & Development 11, 163-169 (2009).

Young, R. L. et al. (2011). Identity of the avian wing digits: problems resolved and unsolved. Dev Dyn. 2011 May;240(5):1042-53.

Taxon of the Week: Beelzebufo.

Yet again, Richard and I are falling behind on delivering on the blog front. For that, we apologise. The next 7 days (hopefully) should bring numerous posts to make up for lost time, including an opinion piece!

Anyway, on with the show. If you follow palaeontological news in any sense, then you’ll probably have heard about a new marine reptile called Atopodentatus. If you haven’t heard of Atopodentatus, imagine if you will the offspring of a basal sauropterygian, Predator, and Cthulu that potentially could have filter fed. Or, you could just check out Brian Switek’s well written Atopodentatus article (with pretty pictures). That’s right, this week we’re going against the grain, and focusing in on a big Cretaceous amphibian, that’s made for a big controversy. I assure you, it’s going to be ribbeting.

Big facts: “we’re gonna need a bigger pond”.

This week, our TotW is Beelzebufo ampinga. Before we knuckle down and attempt to remove the f(r)og from the controversy, let’s get down to the basics. B. ampinga was discovered in 2007 by a team from Stony Brook University from the Maevarano Fm, Madagascar, the remains dated to 70-65Ma (late Cretaceous). The initial paper had little to work with, as the holotype only consists of a few cranial elements, with a few vertebrae, a urostyle and a tibiofibula. However, even with such few remains, the initial size estimates for Beelzebufo are astonishing: with a length of over 40cm, and its head alone estimated at half that in width (20cm!). This immediately bestows Beelzebufo with the crown of the largest frog to ever have lived. Beelzebufo was initially placed within the Ceratophryinae (the common horned frogs), which is unusual and is the basis of most of the controversy surrounding B. ampinga (more on that later). Due to it’s phylogenetic position, Beelzebufo has hyperossification in the skull, stabilising connections between the upper jaw and the skull, a huge mouth, oh, and sharp teeth. What does this mean? Well, like all other ceratophyrines Beelzebufo probably was carniverous, and by being so large, many agree that it would have been an ambush predator of small vertebrates, such as small/baby dinosaurs. So a frog that eats dinosaurs, no wonder they called it Devil Frog.

Evans2008

The holotype of Beelzebufo. Bones that were discovered in white. Modified from Evans et al. (2008).

Earlier in 2014, Beelzebufo was back. This time a (open access!) paper was published, showing off many new specimens of the Devil Frog. These specimens (64 since 2007) were far more complete than the original published findings, and have shown us that it was far weirder than previously imagined. It also gave us a more complete picture of B. ampinga as an organism and as a species. By looking at the squamosal of different individuals it became apparent that there was a lot of intraspecific variation present in B. ampinga, with a size difference of up to 20% present between certain individuals. This has found to be caused by different individuals having different bone growth rates and patterns. Now, the simplest explanation is everyone’s favourite, sexual dimorphism (in modern ceratophryines, the females are larger than males in 90% of cases). However, studies on extant frogs have shown that bone growth patterns and maturation times in anurans can be dependent on other factors such as seasonal food and water availability, as well as temperature.

SOON.

SOON.

Another intriguing fact is that Madagascar at that time was seasonal arid, with dry periods being especially water-sparse. So how does a large amphibian like Beelzebufo cope? Again, material from the 2014 publication (Evans et al. 2014) helps us to possible answer this. Hyperossification (especially in the skull) is prevalent in Beelzebufo. This is apparent in the initial discovery also, but combine this with evidence from Evans et al. (2014), features such as the loss of a tympanic membrane, tall neural spines and cranial exostosis go some way towards confirming that Beelzebufo was a burrower. Thus enabling it to escape desiccation during extreme dry spells. Not only did Evans et al. (2014) provide us with a wealth of new information on an important fossil anuran, but it also came with some fantastic 3D skeletal morphological reconstructions.

Evans2014

The aforementioned pretty digital reconstruction. Also, those posterolateral flanges, phwoar. Modified from Evans et al. (2014).

Big controversy

As has been eluded to, Beelzebufo caused a big splash. Evans et al. (2008) placed B. ampinga within Ceratophryinae, a subfamily found only in South America, based on mainly cranial characters and a supporting phylogenetic analysis. Evans commented that the discovery of a late Cretaceous ceratophryine in this area is ‘unexpected’. Indeed, if you look at the palaeobiogeography it still looks squiffy, with the Madagascar-Seychelles-India tectonic plate losing contact from South America 120 million years-ago. However, even this is debated. Multiple lines of evidence now suggest some land-link was present between South America and Madagascar, including many molecular studies (ratite birds, iguanin lizards et al.) and physical similarities present between South American and Madagascan dinosaurs, crocodyliforms and mammal. So a ceratophryine from the Cretaceous of Madagascar isn’t so crazy, right?

Wrong. Two years after the initial Evans publication Ruane et al. (2010) carried out rigorous testing on the phylogenetic position of Beelzebufo. In Evans et al. (2008), it was apparently established that B. ampinga was a crown-group Ceratophryinae, and a sister taxon to the living Ceratophrys. Ruane et al. had a big problem with this reasoning, stating that the relationship between Beelzebufo and Ceratophrys is supported by 1 out of 81 characterstics, support values for the relationship between these two were also low in the phylogenetic study. Ruane et al. (2010) used molecular phylogenies (with data from extant anurans) in tandem with Beelzebufo, using it as a calibration point, to calculate the timings of the emergence of the MRCA (most recent common ancestor) of modern ceratophryines. With Beelzebufo used in this way, the emergence time of the ceratophryine MRCA was way before the times calculated by other studies, using well established datasets.Ruane et al. came to the conclusion that contrary to Evans’ initial hypothesis, Beelzebufo was a) not a sister taxon of Ceratophrys or b) definitely not a crown-group ceratophryine. However, Ruane et al. don’t really give us more than that, apart from saying it might be some sort of stem-group ceratophryine or a crown-group Hyloidea (a superfamily). If were throwing ballpark ideas around for the phylogenetic position of Beelzebufo, then I’m gunning for a stem-group Hynerian.

dominarrygelxvi

Dominar Rygel XVI, a fine example of Hynerian for all those nerds who don’t watch Farscape.

The Evanpire Strikes back

Not one for lying down Evans et al. (2014), now armed with many more specimens than last time around, resurrected the phylogenetic controversy surrounding B. ampinga. In the 2014 publication, the phylogenetic position of Beelzebufo was restored to the initial hypothesis, stating that Beelzebufo was indeed a crown-group ceratophryine, with this relationship holding true even when different tree-making steps and calibration points were used. Evans et al. also deal with many of the issues raised by Ruane et al. For example, Ruane et al. argue that the low support values between Beelzebufo and Ceratophrys indicate that they might not be sister taxon (and hence Beelzebufo isn’t part of the ceratophryine crown-group). Yet Evans et al. point out that support values are low even in studies that solely consider extant ceratophryids.

The fuzzy phylogenetic positioning given to Beelzebufo by Ruane et al. (maybe stem-group this, or crown-group that) is put under fire by Evans et al. I’ve already said that the Cretaceous MRCA emergence time is Ruane’s main argument against B. ampinga as a crown-group ceratophryine, however what I’ve not yet said (and what Evan’s et al. 2014 love to point out) is that Ruane et al. almost positively place another mid-late Cretaceous frog, Baurubatrachus as a ceratophryid (crown and/or stem), which still means that the MRCA is somewhere in the Cretaceous. Evans was quick (p.54) to point out that Ruane et al. at this point were being somewhat hypocritical in this regard. Finally, Evans points out that the hyperossification present in Beelzebufo is also present in living ceratophryids, another compelling line of evidence in support of the crown-group hypothesis. Despite being confident in their findings, Evans et al. still give a passing mention of the notion that hyperossification (and other ceratophryid characters) may be present due to convergent evolution, however, for the time being (and to conclude!) Beelzebufo appears to be (for the time being) a crown group ceratophryid. *Sighs*.

You've made it past the long-winded bit. Well done, have a pretty picture.

You’ve made it past the long-winded bit. Well done, have a pretty picture.

Big importance

Well done, you’ve made it through a very poorly written account of the s**t-storm which is the phylogenetic positioning of Beelzebufo. By this point, you’ve probably seen the words crown, stem, Beelzebufo, et al. and ceratophryine/d/inae enough to last multiple lifetimes, so then, why should we care about Beelzebufo and it’s position within the ‘tree of life’. You should care for two reasons: 1) the timing of the emergence of ceratophryids, 2) the importance of correctly using fossils in phylogenetic studies.

All glory to the importance of Beelzebufo. You will obey.

All glory to the importance of Beelzebufo. You will obey.

You should remember that the biogeography of Madagascar in the Cretaceous creates problems for the ceratophryid hypothesis. Ali et al. (2008, 2009 2011) have recently noted that land bridges between Madagascar and South America were severed by 115-112Ma. If this is true, (and presuming Beelzebufo and undiscovered others didn’t raft across the seaways, which is actually a large presumption, giving the thick skinned Beelzebufo would weather the salty waters well, for a frog) this pushes the emergence time of ceratophryids to before these dates. This is again contrary to studies that have found the emergence times of crown-group Hyloideans (a superfamily if you remember) to be around 88Ma. As has been stated many times of this blog, any fossil, even an incomplete specimen, if found in the certain places at certain times can cause palaeontologists/phylogeneticists/biologists to have to seriously reconsider the state of the field.

This leads nicely onto the second reason why Beelzebufo is important. Hypocritical arguments aside, Ruane et al., using Beelzebufo as an example, shows how any study using fossils as certain anchor points in phylogenetic studies MUST look closely at the phylogenetic position (and the evidence behind it) of the fossil taxa, and decide if this is appropriate. Any mistakes when involving fossil taxa in these studies affects conclusions with wide reaching implications, such as the divergence/emergence times of certain, and sometimes, very large clades.

And finally, Beelzebufo kinda looks like Hypno Toad. That’s pretty rad.

References

  • Evans, S. E. et al. (2008). A giant frog with South American affinities from the Late Cretaceous of Madagascar. Proc. Natl. Acad. Sci. USA 105: 2951–2956.
  • Evans S. E. et al. (2014). New Material of Beelzebufo, a Hyperossified Frog (Amphibia: Anura) from the Late Cretaceous of Madagascar. PLoS ONE 9(1): e87236. doi:10.1371/journal.pone.0087236
  • Ruane S. et al. (2011). Phylogenetic relationships of the Cretaceous frog Beelzebufo from Madagascar and the placement of fossil constraints based on temporal and phylogenetic evidence. J Evol Biol 24: 274–285.
  • Ali J. R., Aitchison J. C. (2008). Gondwana to Asia: plate tectonics, paleogeography and the biological connectivity of the Indian sub-continent from the Middle Jurassic through end Eocene (166–35 Ma). Earth-Science Reviews 88: 145–166.
  • Ali J. R., Aitchison J. C. (2009). Kerguelen Plateau and the Late Cretaceous southern-continent bioconnection hypothesis: tales from a topographical ocean. J Biogeogr 36: 1778–1784.
  • Ali J. R., Krause D. W. (2011). Late Cretaceous bioconnections between Indo-Madagascar and Antarctica: refutation of the Gunnerus Ridge causeway hypothesis. J Biogeogr 38: 1855–1872.

Taxon of the Week: Postosuchus

In this week’s TotW, Ryan takes us through the posto child of the ‘rauisuchians’, Postosuchus.

When someone mentions the Mesozoic, you instantly think about dinosaurs. Admit it, it’s fine, there’s no judgement on this blog. You also will predominately think about dinosaurs from the Jurassic and the Cretaceous, with good old T. rex and co. (allosaurs, carcharodontosaurs, spinosaurs etc.) ruling the roost at the top of the food chain, whilst sauropod behemoths (amongst other ridiculously sized herbivores) wandering about in herds etc. etc. However, the Triassic (seemingly the Cretaceous and Jurassic’s ugly sister) is often forgotten about. Yes, we don’t have things which are outrageously large or ridiculously bipedal (or do we..?), but in the Triassic, crurotarsans (crocodile-line archosaurs) were having a bit of a field day.

awesomesozoic

The image that immediately springs to mind as soon as you mention ‘Jurassic’ or ‘Cretaceous’. Clearly.

Here on TDS, we think the Triassic (as well as plenty other eras, not just the Jurassic and Cretaceous) is pretty awesome too. The Triassic was a time of recovery, the Permian-Triassic mass extinction event had been and gone (and almost taken all of life on Earth with it). Dinosaurs were just starting out, and sitting on top of the food chain was, you guessed it, Postosuchus. If you look at the skull of Postosuchus kirkpatricki below, look carefully. Back in the 1980s famous palaeontologists thought Postosuchus (along with Poposaurus) could be a tyrannosaur ancestor. You can see where they’re coming from. Postosuchus was first discovered in 1922, and for 60 odd years after that, people didn’t really know what to make of it. First reports penned it as a Coelophysis, 20 years later, other finds were thought to belong to a new phytosaur. It wasn’t up until 1985 that the holotype, a well preserved skull and some postcranial remains, of Postosuchus kirkpatricki was formally announced. 

BronzePostosuchus

Totally not a dinosaur. No seriously.

Weighing in at almost 300kg, at reaching almost 4m when fully grown, Postosuchus was one (if not the) largest predator in the Triassic. With good long distance vision, a decent sense of smell, and a possible Jacobson’s organ, and oh, not to mention, over 7cm dagger-like teeth, this killing machine well may have taken down a fair few aetosaurs in it’s time (not a small feat). So fairly fearsome, but not as impressive as the theropods that were to come later in the Mesozoic, surely? Well, again, no.

tumblr_m3zd8iT4YA1rrpn3bo1_500

These coelophysoids clearly came to the wrong neighbourhood.

What makes Postosuchus (and many other ‘rauisuchians‘) so interesting are its hindlimbs. One of the major dinosaurian innovations was the erect hindlimb posture, enabling more efficient locomotion. In the Triassic, descendants of crocodiles (who now have the ‘sprawling’ hindlimb posture) such as Postosuchus had a go at this hindlimb arrangement (evolutionary speaking). Whilst debated, many palaeontologists view Postosuchus (amongst other Triassic crurotarsans) as being bipeds (or at the very least facultative bipeds). So that means Postosuchus could use it’s forelimbs to kill things as well as it’s terrifyingly huge mouth (like bears do). To summarise, Postosuchus is a nightmare-inducing, killer croc-bear from back in time. It also raises the question (to be investigated by a future blog post on TDS, hopefully) of why exactly did dinosaurs survive through to the Jurassic, and rauisuchians go extinct, and why did crurotarsans go back to being solely quadrupedal?

biobeast-sm

Killer croc-bear from back in time. (Thank you internet).

Told you the Triassic was awesome. (Also, more to come on the locomotory strategies of Triassic crurotarsans to come, right after I finish my final 4th year exams…).

Bonus picture (because it’s cool and reasonably accurate, although not as accurate as the previous picture):

Postosuchus_mural

There’s no escape from the Post(o) Man (not actually a man).

References

  • Case, E. C. (1922). “New reptiles and Stegocephalians from the Upper Triassic of western Texas”. Carnegie Institution of Washington Publication 321: 1–84.
  • Case, E. C. (1932). “On the caudal region of Coelophysis sp. and on some new or little known forms from the Upper Triassic of western Texas”. University of Michigan Museum of Paleontology Contributions 4 (3): 81–91.
  • Case, E. C. (1943). “A new form of Phytosaur pelvis”. American Journal of Science 241 (3): 201–203. doi:10.2475/ajs.241.3.201.
  • Chatterjee, S. (1985). “Postosuchus, a new Thecodontian reptile from the Triassic of Texas and the origin of Tyrannosaurs”. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences 309 (1139): 395–460. doi:10.1098/rstb.1985.0092.
  • Drymala, S. & Bader, K. (2012). Assessing predator-prey interactions through the identification of bite marks on an aetosaur (Pseudosuchia) osteoderm from the Upper Triassic (Norian) Chinle Formation in Petrified Forest National Park (Arizona, USA). Journal of Vertebrate Palaeontology, Program and Abstracts 2012, p89.

What’s New(s): 6/01/2014 incl.; Naked Dinosaurs, Saudi Arabian dinosaurs and Ichthyosaur storms.

Christmas is a time of rest, festive cheer, spending time with loved ones and (probably most importantly) food.       This is seemingly not the case for academics. Firstly, Richard and I have been busy revising for our January finals, so whilst we’ve tried to give you a few juicy morsels over to tide you over the festive season, we’ve not really had chance to bring you the latest news. Coupled with this is that over this year’s festive period there’s been a lot of palaeontology going on. Holiday, what holiday?

blog

PhD Comics, get used to laughing (and crying) along to them as a postgrad.

So here is a What’s News(s) bumper edition, with 5 of the biggest news stories in palaeontology over the festive period. This week, we’ve got Saudi Arabian dinosaurs, naked dinosaurs, ichthyosaurs, body-size trends in evolution and some Hungarian palaeoneurobiology! Since we don’t want to spam you, we might start evolving our What’s New(s) sections so they are weekly, rather than as-and-when the news comes out (unless it’s really cool).

The first Saudi Arabian dinosaurs. Like has been previously stated, new dinosaur finds aren’t rare occurrences. They happen roughly every 1.5 weeks. Big deal right. Wrong (again). Benjamin Kear’s team have discovered a few caudal vertebrae and some teeth from Saudi Arabia, from the Maastrichtian (75 Ma, ish), and have confidently identified the vertebrae to be from a titanosaur, and the teeth to be from an abelisaurid. The confidence of these groupings is the first time that fossils the Arabian peninsula have been able to be classified as dinosaurian without contention. It also stretches the palaeogeographical ranges of titanosaurs and abelisaurids to the northern margin of Gondwana, whilst showing us (with just one find) that dinosaur ecology in this area may have been quite diverse in the mid-late Cretaceous. The papers also open access (over here on PloS One).

saudidinos

A-C: vertebra of a titanosaur from Saudi Arabia; D-F: tooth of a abelisaurid (again from Saudi Arabia). From Kear et al. (2013).

Naked dinosaurs a common sight during the Mesozoic. For a pretty ‘young’ blog, we’ve already mentioned naked dinosaurs (ooo err!) twice. That says a lot about Richard and I. Moving swiftly on… Since the discovery of the feathered Sinosauropteryx in 1996 (and a plethora of other feathered Chinese dinosaurs since) has caused a bit of frenzy. So much so, that even the Jurassic Park conceded, and created this monstrosity (they’ve now de-conceded, and have yet again ignored feathered dinosaurs). Since 1996, palaeontologists have endeavoured to find just how far back feathers go in the dinosaur lineage. Up until the early 2000s, we thought we had it covered, and that feathers were ancestral to theropods (with discoveries such as Dilong paradoxus, a feathered tyrannosaur sparking fierce debate over whether good old T. rex  had a majestic feathered coat). Yet, as always, it only takes one discovery to turn everything upside down. Pscittacosaurus was that discovery. Pscittacosaurus is a ceratopsian (basal relative to the frilled dinosaur celebrity Triceratops), but with some proto-feathers. Crazy times.

bakker deino

Richard’s favourite naked dinosaur, Deinonychus (which probably wasn’t naked at all).

Paul Barrett then set about to try and solve just where the feathered dinosaur bus stopped. He and his team looked at all of the dinosaur skin impressions found to date, looking for any sign of feathers (or similar structures) and then considered the data is a evolutionary context. He concluded that despite Pscittacosaurus, most ornithischians (ceratopsians, ornithopods, pachycephalosaurs and thyreophorans) and sauropods would have had scales. With the majority of dinosaurian clades having scales rather than feathers, Barrett tentatively concluded (at SVP 2013, in sunny Los Angeles) that scales were probably the ancestral condition in dinosaurs.  But by now we know that all it takes is one feathered dinosaurs from the Triassic (or even the early Jurassic) to upheave this study.

The I(chthyosaur) of the Storm. Quick bit of local (for British palaeontologists  anyhow) news for everyone. After heavy storms (no, seriously, before any Americans/Canadians/anywhere with ‘proper weather’ complain) a 1.5 m long partial ichthyosaur skeleton has been revealed at the base of a cliff in Dorset, and is being restored by the Jurassic Coast Heritage organisation. Three ichthyosaurs have been revealed in similar ways after storms in the past year along the Jurassic Coast. So remember kids, 80mp/h winds and floods aren’t all bad.

Ichthyosaur_hharder

That’s right, icthyosaurs can fly. And then they become storms. True story (Not actually true).

Growing fields: body-size trends throughout the fossil record. Whilst by no means is the study of body-size trends through evolutionary history a new field, but Mark Bell has just published a brilliant, relatively short and Open Access (whoop!) introduction to body-size trends in the fossil record. The article really does make you feel rather small (literally). It also goes through some long established rules on body-size evolution (e.g Cope’s rule), whilst also noting some nice examples of giganticism and dwarfism in the fossil record. Finally, he also states that new computer simulations/software maybe able to help us to further understand these trends in the future.

Bell_gigantism_Figure-1

Where’s Wally, PhyloPic edition. (From Bell 2013 and PhyloPic).

The very Hung-a-ry dinosaur brain. This gem of palaeontological news really does show how fieldwork and digital analysis can produce fantastic results. A new find of a partial skull of Hungarosaurus (from, you guessed it, Hungary) has enabled Hungarian palaeontologists to made a cast of the endocranial cavity, allowing them to analyse the braincase of this European anklyosaur. Initial results suggest that the cerebellum (area of the brain associated with motor control) is larger in volume than other ankylosaurs. This may well mean that Hungarosaurus was better able to run than other anklyosaurs (well known for not being the fastest of starters…).

hungarybrain

Endocast of Hungarosaurus. cbl=cerebellum (roughly circled, from Osi et al. 2013)

References:

Kear BP, Rich TH, Vickers-Rich P, Ali MA, Al-Mufarreh YA, et al. (2013) First Dinosaurs from Saudi Arabia. PLoS ONE 8(12): e84041. doi:10.1371/journal.pone.0084041

Mayr, G., Peters, D. S., Plodowski, G. & Vogel, O. Naturwissenschaften 89, 361–365 (2002)

Zheng, X.-T., You, H.-L., Xu, X. & Dong, Z.-M. Nature 458, 333–336 (2009).

http://www.nature.com/news/feathers-were-the-exception-rather-than-the-rule-for-dinosaurs-1.14379

http://www.bbc.co.uk/news/uk-england-dorset-25548426

http://www.palaeontologyonline.com/articles/2014/trends-body-size-evolution-fossil-record-growing-field/

Ősi, Attila, Pereda Suberbiola, Xabier, and Földes, Tamás. 2014. Partial skull and endocranial cast of the ankylosaurian dinosaur Hungarosaurus from the Late Cretaceous of Hungary: implications for locomotion, Palaeontologia Electronica Vol. 17, Issue 1; 1A; 18p;
palaeo-electronica.org/content/2014/612-skull-of-hungarosaurus

What’s New(s): Unidirectional airflow, a load of hot air?

Whilst being old (last week’s) news, the discovery of unidirectional airflow in monitor lizards is:

  1. Really cool.
  2. Really important.
  3. Allows TDS to explain some key methods/principals used by palaeontologists.

Before we get bogged down in phylogentic-y goodness, let me introduce unidirectional airflow. As humans (and mammals more generally) we suck at breathing. Compared to birds, our respiratory system is pretty inefficient, but that’s fine, we’re not running around at full speed all day. Our breathing system is called tidal breathing, and involves the mixing of ‘new’ air and ‘old air’ in the lungs. This means that there’s not a huge amount of ‘fresh’ air in our lungs, meaning, compared to birds (and the like, more on that later) less oxygen enters the bloodstream per respiratory cycle. However birds have employ a neat trick called unidirectional airflow. Essentially, they’ve got a few more respiratory chambers which allows oxygen to enter the bloodstream during both inhalation and exhalation (by virtue of being a one-way system). This means a birds respiratory system are relatively efficient, which is great for them, as flying’s seriously hard work.

1.14355_MonitorLizard_Skeleton_edit

Unidirectional air flow, shown off excellently by our friend the Savannah monitor lizard.

Up until 2010, unidirectional airflow was only thought to exist in birds. But it has also been found in crocs (Farmer et al. 2010). So another scaly thing with a more efficienty respiratory system than us, big whoop. Yes actually, because with the help of Extant Phylogenetic Bracketing (EPB) we can learn a lot more about the success of diapsids (fancy name for the group containing all the birds, crocs, lizards, tuataras and oh, dinosaurs) during the Mesozoic.

Extant Phylogenetic Bracketing is essentially using common sense to infer anatomy and behaviour in extinct organisms. For something so widely used today, it’s only really been applied in palaeontology since 1995 (Witmer 1995). At it’s core we use our knowledge of what anatomical features (and possibly behaviour) modern organisms have, and put them into an evolutionary context to infer what features their common ancestors might have had. Birds, crocodiles and lizards are an excellent example of how palaeontologists have mastered EPB. So to use UA as an example, if we know birds have it, as do crocs, we can infer that dinosaurs may have had a UA respiratory system, because the last common ancestor of birds, dinosaurs and crocodiles (point A on the diagram below) may have had UA.

UA_phylotree

Very abridged (i.e no pterosaurs, sorry) of the diapsid tree (excluding Mesozoic marine reptiles). A is the last common ancestor of crocs and birds, B is the origin of birds, crocs, dinosaurs and lizards.

Cool story bro, but what about monitor lizards? Ok, so using EPB we’ve inferred that dinosaurs have UA due to their extant relatives both having UA. So if we now factor monitor lizards into the equation, we can now infer that the last common ancestor of birds, dinosaurs, crocs and lizards (i.e diapsids, point B on the diagram above) probably used unidirectional airflow as a respiratory strategy. This means that UA (originally thought to be unique to birds) originated 100 million years before birds evolved. But that’s not all.

1.14355_Image-1_5_SavannahMonitorLizard_CherylErtelt

Just another scaly thing with a more efficient respiratory system than us. All hail the savannah monitor lizard.

Lizards and Birds (and to a certain degree, crocs) are hugely successful organisms. A more efficient respiratory system has certainly aided in their almost global (niche) domination. This may explain why diapsids (dinosaurs in particular) were so diverse and successful during the Mesozoic (and also perhaps why they were so bloody big). So it looks like savannah monitor lizards are a…breath of fresh air.

References

Farmer, C. G. and Sanders, K. (2010). Unidirectional Airflow in the Lungs of Alligators. Science 327, 338–340.

Witmer, L. M. (1995). “The extant phylogenetic bracket and the importance of reconstructing soft tissues in fossils”, in Functional morphology in vertebrate paleontology (ed. J. J. Thomason), pp. 19–33. Cambridge University Press

Schachner, E. R. et al. (2013). Unidirectional pulmonary airflow patters in the savannah monitor lizard. Nature http://dx.doi.org/10.1038/nature12871