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.

Advertisements

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.

What’s New(s): Acheroraptor.

‘Whats New(s)’ is our new (poorly titled) news and views-esque section, where we keep you up-to-date on the latest findings in palaeontology, as well as explaining some key ideas behind them. For TDS first ever What’s New(s) we’ve got the exciting discovery of Acheroraptor! It also represents the first post on TDS with actual content (and dinosaurs). Huzzah!

New dinosaur fossils are being found all year round. No big deal, right? Wrong. Quite a lot of these new fossils fall under 3 very interesting categories:

  1. Crazy looking (a technical term).
  2. Exceptional preservation (and a shameless Bristol Palaeo plug).
  3. Macroevolutionary importance.
acheroraptor_fossil

Maxilla (top) and dentary (bottom) of Acheroraptor (with non-isolated teeth).

Acheroraptor falls into number 3. Not only does it have one of the best names ever, Acheroraptor temertyorum (literally meaning ‘Underworld thief’), but it’s one of the first major fossils (previously all we had was just isolated teeth) of dromaeosaurs (velociraptors and their close relatives) from North America in the Late Cretaceous. I say ‘major fossils’ but it’s still only 2 bones in the skull, a full maxilla and an almost complete dentary. Oh, and some non-isolated teeth. Nonetheless, the little blighter is (apparently, according to a wonderful reconstruction by Danielle Dufault) a cutie!

archeroraptor

As ‘underworld thieves’ go, this ones adorable.

So why is it important? Palaeontologists reconstruct evolutionary relationships by looking at how morphological features vary between different species. So, the more complete the fossil record is for a species, the more features you can compare, and the more confidence you can have when inferring the evolutionary relationship. So, going from a few isolated teeth, to a couple of (relatively) whopping great big skull bones is a fantastic leap! So, Acheroraptor has (despite being ‘American‘) been found to be more closely related to Asian dromaeosaurs, such as Velociraptor mongoliensis. This means that there was more faunal interchange between ‘America’ and ‘Asia’ back in the Late Cretaceous.

Cool right?

References

Evans, D. C., Larson, D. W. and Currie, P. J. (2013) A new dromaeosaurid (Dinosauria: Theropoda) with Asian affinities from the latest Cretaceous of North America, Naturwissenschaften, 100(11), 1041-1049