What’s new/s 03/03/14

What’s news has been neglected a bit over the last few weeks, but fear not! Here are five exciting palaeo news stories from the last month or so:

Placoderm faces

For no particularly good reason, placoderms are a group close to my heart.  This group of fish existed during the Devonian, and are the earliest example of vertebrate with jaws in the fossil record,  As well as being generally awesome, they are also crucial to understanding how gnathostomes, the jawed vertebrates, evolved from their jawless ancestors.  Dupret et al have CT imaged a primitive placoderm, Romundina, and have shown that it has a mixture of jawless fish (‘agnathan’) and gnathostome  cranial  characters.  As with so much of evolution, the transition to attaining jaws seems to have been piecemeal, part by part, an example of mosaic evolution, with cerebral proportions remaining largely unchanged with the evolution of jaws.

Romundina

Romundina in all its glory. This is the head with front end to the left, the large, round holes are the orbits. (from phys.org)

Even more Burgess Shale

The Cambrian is famous for the weird and wonderful fossil taxa that existed during it, and the most famous Cambrian fossil site is the Burgess Shale, in the Canadian Rockies.  Since the early 20th century the incredible preservation of this site has given us an invaluable window into life 500 million years ago.  While the Burgess Shale animals were famously argued by Stephen Jay Gould to represent experimentations in body plans alien to anything alive today, more recent work has shown that actually these animals are early relatives of groups such as arthropods (ie. insects, crustaceans etc) and vertebrates (ie. you).  The other week another site was described from the Burgess Shale; hopefully this will mean we’ll see lots of new Cambrian beasties over the next few years, as well as more information on known ones,  continuing to fill in our picture of early animal evolution.

Burgessnew

A range of weird and wonderful Cambrian fossils from the new assemblage. (from Caron et al)

Aquatic Acanthostega

We already met Acanthostega, the earliest known tetrapod, a few weeks ago, when we were looking at Tiktaalik and the transition of vertebrates onto land.   Acanthostega possesses a mixture of aquatic and terrestrial qualities: like a fish, it has gills and a tail fin, but like a modern tetrapod it had digits and a ‘neck’ between the head and body.  This has been taken to demonstrate that tetrapods actually evolve many ‘adaptations to land’, such as digits, while the still lived in water, in contrast to the historical view that a (presumably rather optimistic) fish crawled onto land and only then adapted to it. Recent work by Neenan et al suggests that Acanthostega’s jaw was adapted to aquatic, rather than terrestrial, feeding, which they argue refutes recent suggestions that it might have fed on land, or at least above water.

Optimistic fish

An optimistic fish (from Pixar.wikia.com)

Playing around with flight

Imagine, if you will, a bird.  Chances are that you’re imagining something that’s probably feathered and beaked*.  The fossil record, however, shows us that many traits that we associate with birds, such as feathers and beaks, evolved before birds came into existence as a group.  Feathers are perhaps the best example, found in many dinosaurs not particularly closely related to birds, but it is also true of various skeletal characters.  Work by Mark Puttick and others shows that this is the case with the comparatively long forelimbs of birds, which originated before the origins of the group, amongst earlier dinosaurs.  Gliding dinosaurs like Microraptor suggest that many groups were independently evolutionarily ‘playing around’ with feathered gliding, it was just the birds that happened to evolve powered flight and make it through to today.

*If not, you may want to double check that you know what a bird is.

Microraptor

Microraptor: Evolutionary experimentation with flight? (from nhm.co.uk)

Primitive live birth in ichthyosaurs

As we’ve seen before on The Dinosirs, ichthyosaurs were a very successful group of Mesozoic reptiles, highly adapted to an aquatic life.  One oft quoted adaptation viviparity, or live birth, as a fully aquatic amniote can’t get back onto land to lay eggs.  This is also seen in other groups of marine reptile, such as plesiosaurs and mosasaurs.  However, a recent paper by Motani and others has suggested that actually live birth was present in ichthyosaurs’ terrestrial ancestors before they became aquatic.  They argue this based on a fossil of a very early ichthyosaur, Chaohusaurus, which appears to have been fossilised giving birth.  While this is fairly common in ichthyosaur fossils, all previous fossils have been found giving birth to babies tail first as in modern day whales, possibly as an adaptation to prevent suffocation.  This fossil demonstrates that Chaohusaurus  gave birth head first, as in most terrestrial vertebrates.  Motani et al argue that this demonstrates that ichthyosaurs evolved from terrestrial viviparous ‘head first’ ancestors, only later switching round as an adaptation to marine life as in whales today.  This is contrary to the traditional view, but does fit with our picture of modern reptiles: many groups of lizard are viviparous.

Viviparity icthyo

Chaohusaurus.: green, red and blue below are the ribs, paddle and tail of the mother respectively. Small ichthyosaur can be seen com in out headfirst in yellow. (from Motani et al)

 

References

Dupret et al (2014) A primitive placoderms sheds light on the origin of the jawed vertebrate face, Nature

Caron et al (2014) A new phyllopod bed-like assemblage from the Burgess Shale of the Canadian Rockies, Nature communications

Neenan et al (2014) Feeding biomechanics in Acanthostega and across the fish-tetrapod transition, Proc. Roy. Soc. B

Puttick et al (2014) High rates of evolution preceded the origin of birds, Evolution

Motani et al (2014) Terrestrial origin of viviparity in Mesozoic marine reptiles indicated by Early Triassic embryonic fossils, PLOS One

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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