Plates, spikes and a brain the size of a plum ...

At long last I can finally reveal to my friends and colleagues why it has taken me much longer than usual to respond to those emails, admin and specimen requests, and why my contributions to our joint grant and research projects have been somewhat tardy. For the past year, I’ve been heavily involved in a secret museum project: the acquisition of a spectacular new dinosaur specimen. With the publication of a piece in The Telegraph today, the embargo has come to an end, and I can now announce that the Natural History Museum has succeeded in acquiring a skeleton of the iconic Jurassic North American dinosaur Stegosaurus stenops, the most complete skeleton known for this species. The new skeleton is going on permanent public display in the NHM on 4th December 2014.

Our new Stegosaurus skeleton, laid out to show all of the elements together and giving an impression of its overall scale. Around 90% of the specimen is present, including an almost complete disarticulated skull and an essentially complete set of plates.

The specimen has been in London since late 2013. Since then, Charlotte Brassey, Susannah Maidment and I have been crawling over every inch of the skeleton to gather basic anatomical data using traditional methods, CT scans, 3-D laser scans and more. We’re currently preparing a series of papers on Stegosaurus anatomy and biology, the first of which are close to submission. This work is being carried out with a number of other colleagues, all of whom were sworn to secrecy (we’ve all been operating under non-disclosure agreements to save our thunder for the unveiling), and whose roles will be revealed as our papers start to come to fruition. Charlotte and I have also been very heavily involved in all other aspects of the project, which includes the specimen installation, interpretation and forthcoming public programme, so it will be great to finally see the skeleton in its full glory in a couple of weeks time. It’s been a hectic and exhausting, but exciting and rewarding, experience - especially while trying to conduct the work discreetly while fulfilling my various other duties at the museum and elsewhere.

Watch this space for more details. The specimen will be mounted in the Earth Hall (Exhibition Road entrance, at the base of the escalator leading into the large globe) and will greet visitors as they arrive. A big thank you to all of those that have helped so far and who have also indulged my delays on so many recent occasions! I'll reveal more over the course of the next few months.

Theropod envy?

When giving conference or public presentations, I often use the opportunity to take a swipe a theropods: after all, most of my career has been spent working on dinosaur herbivores, which often end up in the capacious guts of their carnivorous relatives. However, it's not because I genuinely hate theropods per se - some are amazing animals, and even though Tyrannosaurus is, without doubt, over-exposed and over-rated it is still a neat animal. I've even found myself working on theropods from time-to-time, though admittedly I still have a strong preference for the more diverse and disparate herbivores. The main reason I feel I have to insult theropods (and by extension theropod workers) is simply the hyperbole that surrounds these animals. A mouthful of sharp teeth, claws, and endless speculations over dino-celebrity death matches seems to get people weak at the knees, clouding all sensible judgement regarding new claims about their palaeobiology. Who really cares if one giant theropod was 50 cm longer than another? Such trivia has no real effect on our knowledge of theropod biology and evolution. Although the media might be blamed for fanning the flames of theropod adoration, this would be unfair - they simply give people what they want and there are plenty of people out there, both professionals and public, who idolize theropods in ways analogous to 'A'-list celebrities. This manifests every year at Society of Vertebrate Paleontology meetings, for example: theropod talks are often packed to the rafters (thanks mainly to work on feeding and behaviour: big fluffy killer death lizard syndrome), whereas the room feels distinctly emptier when similar talks start on herbivorous dinosaurs.

A cast of Giganotosaurus in the Museo "Carmen Funes" Plaza Huicul, Argentina

More seriously, this idolatry extends to scientific publication too. I'm frequently teased by colleagues in other disciplines about how easy it must be to get dinosaur papers into top journals like Nature and Science - after all, dinosaur papers appear in both venues regularly, despite the fact that dinosaur workers represent only a tiny fraction of scientists worldwide. However, while vertebrate palaeontology clearly punches above its weight in this regard, there is a bias - almost all dinosaur papers in these journals are on theropods, while the other two-thirds of dinosaur diversity do far less well (and analytical papers dealing with dinosaurs as a whole are exceptionally rare). These theropod papers generally fall into two categories - announcements of new dinosaurs with feathers, or some other aspect of the dinosaur/bird link - or discoveries of non-feathered theropods with potentially interesting palaeobiological features or geographical/temporal range extensions.

This is perhaps exemplified by the new paper in Science published last week on the iconic North African theropod Spinosaurus (Ibrahim et al., 2014). In this widely reported paper, the authors describe a new articulated skeleton of this animal and use it to update various aspects of the animal's anatomy. The hook for the paper was that Spinosaurus might have been a largely aquatic animal - and when not aquatic might have been quadrupedal - an unusual (and potentially interesting) adaptation for a theropod. This news flashed around the world on the media, Facebook and Twitter, with few critical voices. However, the hype generated by the release (in no small measure due to the heavy involvement of National Geographic) overlooks some important details.

Importantly, most dinosaur workers had already accepted that spinosaurs were probably unusual dinosaurs that did spend a lot of time in water. This was based on numerous lines of evidence:
1. Snout and tooth morphology: convergently looking like a crocodile and potentially engaged in croc-like feeding behaviour. Those teeth aren't for slashing, but could have been good at holding slippery prey;
2. Weird forelimbs: the big claws have long been suggested as tools for gaffing fish from the water, and it has even been suggested that the robust humerus might have been associated with quadrupedality;
3. Gut contents: the British spinosaur Baryonyx has fish remains in its gut contents (the only gut content known for a spinosaurid);
4. Oxygen isotopes: these suggest that spinosaurs ate far more aquatic prey than other dinosaurs and may have spent more time in/near water as a result;
5. Palaeoenvironments: the North African localities yielding Spinosaurus have long been though to be very wet - with wide meandering channels, which, coincidentally are full of big tasty fish.

This work was all done previously by palaeontologists going back to Strömer, most notably by Angela Milner, Alan Charig, Andrew Cuff, Emily Rayfield and colleagues in their work on Baryonyx and Spinosaurus (Charig & Milner, 1986, 1997; Cuff & Rayfield, 2013) and by the isotopic work of Romain Amiot and colleagues on Spinosaurus (Amiot et al., 2010), as well as numerous other less detailed accounts. Although these papers are cited in the recent Science contribution, they are not given due credit for establishing the idea of aquatic spinosaurs – the new observations made on the additional material are really only the icing on the cake for the story of spinosaur habitat preference. Moreover, doubts have emerged over the proportions of the new skeleton (see the excellent blog entry by Scott Hartman) and given the vagaries associated with the collection of the material (which was  collected by professional fossil dealers who did not  keep or provide detailed field notes to corroborate the association of the skeleton) additional assurances are needed to support the claims of the authors in the Science article. If the new specimen is genuinely associated and the problems noted thus far can be accounted for this would be a neat discovery (even if it is a theropod): a new, good specimen of an animal known otherwise from published images and isolated material. However, extraordinary claims merit extraordinary levels of evidence.


Given the foregoing I'm left wondering why the editors thought that this might be suitable for Science - a journal that wants to publish transformative research. Is it a new taxon? No. Does it tell us something distinctive about evolution or dinosaurs that we didn't know before? No. This is really a specialist paper, updating our knowledge of a single taxon that was named nearly a century ago, although one with an interesting history. My theory? It's a big scary theropod ... I doubt very much that anyone working on a new sauropod or ornithischian skeleton belonging to a named taxon would stand much chance of getting similar papers published. That's why I'm envious of theropods ...

References:

Amiot, R. et al. (2010). Oxygen isotope evidence for semi-aquatic habits among spinosaurid theropods. Geology 38: 139–142 doi:10.1130/G30402.1.
Charig, A. J. & Milner, A. C. 1986. Baryonyx, a remarkable new theropod dinosaur. Nature 324: 359–361.
Charig, A. J. & Milner, A. C. (1997). Baryonyx walkeri, a fish-eating dinosaur from the Wealden of Surrey. Bulletin of the Natural History Museum London 53: 11–70.
Cuff, A. R. & Rayfield, E. J. (2013). Feeding mechanics in spinosaurid theropods and extant crocodilians. PLoS ONE 8(5): e65295. doi:10.1371/journal.pone.0065295.
Ibrahim, N. et al. (2014). Semiaquatic adaptations in a giant predatory dinosaur. Science DOI: 10.1126/science.1258750.

Opening up on Open Access

I'm a huge admirer of the hard push we're currently witnessing to make published research freely accessible to all who need it. The move towards universal Open Access (OA) is going more slowly than some would like, but there has been a huge shift in perception among academics, publishers and funders, most of it positive. Many of the issues in this debate have already been aired extensively, but I have a few brief observations (well, mini-rants) based on my own biases and experiences, both as a journal editor (both for commercially and society published journals), someone with a hand in running academic societies, and as an author. This is going to be a stream of consciousness, so apologies in advance ...

1. OA costs authors money. Please don't lambast people for not publishing their papers with Gold OA - they may not be able to afford it. Average fees for Gold OA are high (around $2.5K on average in my field) and at a time when budgets are tighter and tighter finding money to support publications gets trickier. RCUK recently provided the institutions that they fund with block grants to pay for work done via their grants to be published OA. However, these block grants are inadequate: one recently completed NERC grant of mine (which was funded prior to the new rules coming in) generated nine papers - the costs of making each of these Gold OA would have exceeded my institution's entire RCUK annual block grant. In this case, the funding body has imposed a knee-jerk response to a call for more OA, without providing the people that it funds adequate resources to do so. The situation for people in small institutions in developing counties is likely to be even harder.

2. OA costs publishers money. It could be argued that OA fees should be lower (and some places like PLoS and PeerJ manage this, which is admirable), but there is a fixed minimum cost of publishing a paper in any format due to the need to employ people to run journals. Even online journals require IT  and editorial staff, as well as the staff needed to look after their pay and pensions, legal issues,  maintaining their offices, etc. Costs start to balloon further when printing physical copies and distributing them. Although many large commercial publishers might have slack in their accounting lines to offer lower fees, thanks to economies of scale, many smaller publishers will not. Let's not forget many excellent journals are published by small academic societies, which serve niche communities well, and that are entirely financed by membership dues or small investment portfolios. Many small academic societies could not exist or promote new work without the revenues generated by publications, which are usually fed back to benefit the members of those societies directly. Give these guys a break, at least.

3. Green OA is great. Authors retain copyright over the final versions of their publications in their original form - i.e. the non-formatted final version they submit to the publisher. Posting of this after an embargo period is free, legal and gets the data out. It might not allow access to the beautiful proofed version of the article, but it does the job. Although access to the article isn't instant - it's still free after a relatively short lag. Please remember OA and instant access are not necessarily the same thing. Except in a few very rare instances, does it really matter if you have to wait six months for public access to a paper? (Especially given point 4, below). Admittedly the world might benefit from rapid medical or technological advances based on immediate OA, but let's be honest - it's 99.9% likely that the people with the insight and training to make those advances will have instant access to it through an institutional library or professional network anyhow.

4. Rediscover some scholarly skills. To some extent, I regard the need for instant gratification with some amusement. I did my PhD at time when email was just starting to be used widely (I had to go to a university computer centre to use it!) and PDFs did not exist. Amazingly, I still managed to access all of the material I needed, essentially for free, through libraries, interlibrary loans, requesting reprints, and asking colleagues if they had copies of particularly hard to get publications that I could borrow from them. Getting away from Google and asking a human being for help might actually have some side benefits for your research. All of these are forms of free information exchange that existed for centuries before exchanging PDFs. Ask the author for a PDF of that paywalled paper. You might actually learn something else by accident.

5. A historical perspective is interesting. Originally all scientific publication was funded by private patronage - authors had to pay to publish their work, either directly (often via the historical equivalent of crowd-sourcing) or via high membership dues to a handful of elite societies. Handing over publication to commercial publishers actually removed the need for authors to pay - scientists swapped the initial cash outlay for the fact that commercial publishers would profit from their work. So, the rise of academic publishers allowed people who formerly couldn't pay to get their research published. Free to the author at the point of submission. We've now come full circle, with authors again expected to pay upfront for Gold OA. We're effectively arguing for a nineteenth century financial model, though admittedly a better version of it in which papers are much easier to find for everybody...

In conclusion, it would be great if we could publish everything instantly for everyone and - ulimately - I would be totally in favour of this approach. Where possible, I currently use Gold OA for some of my work but, frankly, pressures to publish in certain venues (in terms of career advancement and visibility) and lack of ready funds often prevents this. However, until we work out where the money to pay for Gold OA  will come from we will have an extended period with a mixed model of Green and Gold OA, as well as paywalls for some publishers that hold out for profits either because they want to or simply have to in order to survive. The main ways this might happen are reductions in OA fees associated with a total abandonment of print journals (saving on printing and posting), less reliance on editorial offices (e.g. less proofing - as happens with PLoS ONE - which has pros and cons), some unprecedented drops in expected profit margins for commercial publishers (good luck with the shareholders on that one), and/or governmental intervention to either cap profits on relevant publications or to provide the money to make up the shortfall between the two.

Publishing on private specimens

Martin Munt and I recently published a short letter in the august journal Nature, commenting on their publication of the beautiful, but privately-owned, eleventh Archaeopteryx specimen (Barrett & Munt, 2014). While we're grateful that Nature took our concerns seriously enough to publish on this issue (especially as our letter was intended as a direct criticism of their editorial policy in allowing a private specimen to be published) they heavily edited our original letter, so that the published version omits some of the more nuanced and general points that we wanted to make. Although Martin and I agreed readily to publication of the edited version - so that we could open the debate on this question more widely - I'd like to make the content of the original available here. As an aside, in the name of openness and full disclosure, Martin and I sent this original text to the authors of the Archaeopteryx paper: we have since had a constructive discussion with them and they paid us the same courtesy by sending the draft of a reply. Text of the original letter ran as follows:

"Collaborations between private fossil collectors and professional palaeontologists generate significant mutual benefits, facilitating access to productive localities and important specimens and remedying the overlooked scientific contributions of amateur collectors. Such collaborations should be encouraged where they bring new material and data into the public domain. However, publication of fossil specimens held in private collections is problematic due to issues surrounding future accessibility and the independent verification of published observations. Journals have a duty to ensure the repeatability of the observations forming the basis of new scientific interpretations prior to publication: for this reason, many journals refuse publication of specimens held in private collections. Foth et al. (Nature 511, 79–82; 2014) described the spectacular eleventh specimen of the earliest bird Archaeopteryx and documented features of the plumage that were previously unknown for this pivotal taxon. While we congratulate the authors and owner for making this information available, there is, however, no guarantee of access to this specimen for other researchers. This Archaeopteryx has been registered under the ‘Act to Prevent the Exodus of German Cultural Property’ (see http://www.gesetze-im-internet.de/englisch_kultgschg/englisch_kultgschg.html), a positive move that requires its whereabouts to be recorded and that prevents the loss of German palaeontological patrimony. Nevertheless, this act has no provision guaranteeing access to future generations of researchers, with access remaining at the owner’s discretion. Without access, these published observations cannot be independently verified, reducing the utility of the specimen to the scientific community. We urge Nature, and other journals interested in such material, to consider these concerns more seriously and to ensure that all authors submitting to the journal can provide meaningful assurances regarding future access to the material on which they publish."

Barrett, P. M. & Munt, M. 2014. Private collections hold back science. Nature 512, 28. (doi:10.1038/512028a)

An unexpected ornithischian

We know surprisingly little about the early evolutionary history of the ornithischian dinosaurs (Irmis et al. 2007). Indeed, the global record of Late Triassic ornithischians consists of only three partial specimens and all of these suffer from incompleteness and have suffered controversy over their exact geological ages and phylogenetic positions. The situation improves in the Early Jurassic with rich faunas from southern Africa and other material from Europe and North America. Nonetheless, few of these sites are well dated, meaning that they cannot place precise constraints on the timing of key events in Ornithischia.

Today, my colleagues and I were excited to announce the discovery of a new early ornithischian that sheds some much needed light on the early stages of their evolutionary history – Laquintasaura venezuelae. Laquintasaura was a small biped, around 1 m in total length, and is known on the basis of at least four individuals that were found together in a rich bonebed (Barrett et al. 2014). The name is based on the La Quinta Formation, from which the material comes, and the country of Venezuela, honouring the fact that Laquintasaura is the first Venezuelan dinosaur and, more broadly, the first to be named from the whole of northern South America. The first specimens were found in the early 1990s and continuing fieldwork by Marcelo Sánchez-Villagra and collaborators has led to the accumulation of a large collection of material, numbering many hundreds of individual bones. Marcelo and I first started working on this material together when he joined the staff of the Natural History Museum in the mid-2000s, but the pressures of other work and the need to find additional diagnostic material led to a long incubation period for the paper.

Laquintasaura provides us with several insights. Critically, we were able to use high-precision radiometric dating techniques to provide a maximum age for the bonebed of 200.9 Ma. This places the deposition of the bonebed within 1 million years of the end-Triassic extinction event, which has a number of implications. It could mean that ornithischians went through the extinction relatively unscathed and/or bounced back very quickly after the extinction. It might also indicate that ornithischians, which were previously rare, benefitted from some kind of ecological release in the wake of the extinction that allowed them to diversify and increase in abundance in a way that wasn’t possible prior to the extinction. Maybe key competitors or predators were wiped out or reduced in number, although such ideas are difficult to test.

The occurrence of at least four individuals in the bonebed – and probably many more (some material remains unprepared and there is still potential for further discoveries at the site) – is intriguing. It hints at the possibility that these little dinosaurs were living in a social group at the time they died. Histological work indicates that the smallest individual we found was around three years old, while the largest was 10–12 years in age. Could this have been a small multigenerational herd? If so, it would be a very early example of ornithischian sociality. More work is needed on the taphonomy of the site to establish exactly how it was formed to confirm or reject this proposal.

The provenance of the new dinosaur is also interesting. Very few dinosaur localities are known from so close to the palaeoequator – indeed it has been suggested that arid climatic belts either side of the equator might have prevented large animals from colonising this region. At a stroke, Laquintasaura shows that dinosaurs were capable of living in this area, whose climate is thought to have experienced seasonal semi-arid and moist intervals.

A quick word on the lovely reconstruction of Laquintasaura produced by Mark Witton. As some of you may know, I have a pet idea that many basal dinosaurs were omnivores, and I wanted this new image to show something other than the usual docile herbivore munching on a fern. The teeth of Laquintasaura are perhaps its most unusual feature as they possess many ‘carnivore-like’ features (they are long, slender and slightly recurved) – these features suggest to me that they were used not only for plants, but also for small animal prey (at least some of the time).

This paper was a big team effort and I’d like to thank all of the other team members: Richard Butler and Randy Irmis for their ornithischian expertise; Roland Mundil for conducting the radiometric analyses; Torsten Scheyer for working out just how old each individual was; and especially Marcelo for his invitation to work on this exciting material, sorting out all of the logistics, and for his constant reminders that I had to get on and finish the work. In addition, we also relied on the efforts of many preparators at several institutions (Scott Moore-Fay, J. Carillo and U. Oberli) and Mark Witton and Scott Hartman's artistic talents. Now on to the longer-term project that will be the full description …

Barrett, P. M. et al. 2014. A palaeoequatorial ornithischian and new constraints on early dinosaur diversification. Proceedings of the Royal Society B 281, 20141147. (doi:10.1098/rspb.2014.1147)

Irmis, R. B. et al. 2007. Early ornithischian dinosaurs: the Triassic record. Historical Biology 19, 3–22. (doi:10.1080/08912960600719988)

Out with a bang!

Dinosaur extinction has always excited the imagination – what forces could possibly account for the disappearance of such a dominant and charismatic group? More than 100 different theories have been published to account for the extinction, ranging from the interference of meddling aliens, to collisions between the Earth and roving lumps of galactic antimatter and the possibility of some malign dinosaur pandemic flu. Almost all of these theories have been shown to be lacking in evidence (or just plain crazy). However, several events at the end of the Cretaceous Period have stood the test of scientific scrutiny. These are: the impact of a large meteorite (around 10 km in diameter); the climatic effects of the extensive volcanic eruptions that formed the stacked lavas of the Deccan Traps in India; and a series of more general, long-term global environmental changes, including sea-level rises and climatic shifts. Recently, a multi-disciplinary team reviewed the evidence for the asteroid impact, concluding that the timing of the impact, whose crater is centered on the small town of Chicxulub on the Yucatan Peninsula of Mexico, was the perfect smoking gun to drive the extinction (Schulter et al. 2010). However, dissenting voices (my own included) were quick to reply, noting that the longer-term effects of volcanism and environmental change might have been largely to blame (Archibald et al. 2010).

In order to get a fresh perspective on what happened to the dinosaurs, my colleagues Steve Brusatte and Richard Butler assembled a team of palaeontologists to re-examine the final stages of dinosaur evolution. Together, we took a cold, hard look at the diversity of Late Cretaceous dinosaurs during the last 20 million years of their reign, reanalysing the most recent data on dinosaur distributions and combining this with the latest information on climatic conditions and the timing of Deccan volcanism and the Chixuclub impact. There was much discussion and debate within the team until a consensus emerged: the end result of these deliberations was published online today in the journal Biological Reviews (Brusatte et al. 2014). 

Our new analyses find little support for long-term declines in dinosaur diversity and abundance in the lead-up to the extinction. Some herbivore groups in North America were suffering slightly, but this pattern was not repeated in other areas of the world. Instead, the extinction appears to have been geologically abrupt: an observation that rules out the more gradual declines predicted by extinction models reliant on slower mechanisms of global change. Moreover, the major pulses of Deccan volcanism do not correlate well with this sudden extinction. Consequently, we concluded that the abrupt global extinction of so many dinosaur lineages coincided best, and was most consistent with, the Chicxulub impact. Nevertheless, the stressed herbivore populations in North America may be hinting at the fact that at least some dinosaurs were under environmental strain prior to the impact. It seems reasonable to propose that longer-term mechanisms might have adversely affected at least some dinosaurs, making them more vulnerable to the cataclysmic effects of the impact.

It’s interesting to speculate what might have happened if the asteroid had not hit at this precise moment in time. Dinosaurs were successful and diverse, exploiting a wide range of niches from pole-to-pole. Although re-imagining historical events is always risky, it seems reasonable to speculate that had the asteroid arrived at a time when dinosaurs weren’t already stressed then some of them might have survived and even prospered until the present. Of course, it can be argued that this particular experiment has already been run – birds are nothing more than feathered, flying dwarf dinosaurs and are far more diverse than their extinct relatives. It could even be argued that the asteroid was just a blip in dinosaur evolution rather than a catastrophe: after all, the explosive radiation of avian dinosaurs was largely a post-impact event, even if the extinction took out all of their larger (and I’d suggest more exciting) non-avian relatives.

Archibald, J. D. et al. 2010. Cretaceous extinctions: multiple causes. Science 328, 973.

Brusatte, S. L. et al. 2014. The extinction of the dinosaurs. Biological Reviews. doi:10.1111/brv.12128

Schulte, P. et al. 2010. The Chicxulub asteroid impact and mass extinction at the Cretaceous-Paleogene boundary. Science 327, 1214­–1218. doi; 10.1126/science.1177265

A fuss about feathers and fuzz

For the past 24 hours the palaeontological community has been abuzz, following the unveiling of a new Siberian dinosaur in the high-impact journal Science (Godefroit et al. 2014). The find, a small 1-m long bipedal herbivore named Kulindadromeus, is a member of the major dinosaur group Ornithischia and was closely related to the group that includes the ornithopods (such as Iguanodon) and ceratopsians (such as Triceratops). It comes from rocks of Middle–Late Jurassic age, and is dated at somewhere between 169–144 million years old. In many respects, the anatomy of Kulindadromeus is unremarkable – representing a fairly standard small ornithischian – but the important thing about this animal is the evidence for preserved skin structures, which have led the authors to conclude that it represents a rare example of a feathered ornithischian.

Until relatively recently, all dinosaurs were viewed as scaly – a proposal supported by numerous dinosaur cadavers with skin impressions that show standard reptilian scales around the body. This was overturned by a series of spectacular and beautiful discoveries from Germany, Canada and especially China of exceptionally preserved dinosaur skeletons with clear evidence of ‘protofeathers’ or more complex branched down-like or true feathers (e.g. Norell and Xu 2005). Since the first of these discoveries in the mid-1990s more evidence has accrued to show that feathers were not an exclusively avian feature, but had their deep evolutionary origins somewhere in the theropod family tree. An additional twist was provided to the story in the 2000s, with the description of unusual quill-like and branched structures in the ornithischians Psittacosaurus and Tianyulong (e.g. Zheng et al. 2009), which have been suggested by some to be evidence that feathers and their precursors were actually widespread across dinosaurs as a whole and not restricted to birds and their theropod ancestors.

Kulindadromeus possesses several interesting skin structures, which include scales, simple filaments and unusual (and so far unique) structures with several ribbon-like filaments arising from a single basal plate. The authors of the paper have suggested that these structures support the view that ornithischians were also feathered (at least as juveniles) and that this in turn indicates that feathers had a deep origin within Dinosauria. Nevertheless, some questions remain regarding the identity of the structures found in Kulidadromeus.

Firstly, the authors have so far been unable to determine the original composition of the filament-like structures – were they definitely composed of beta-keratin, as would be expected if they were feathers, or do they represent something else? Secondly, the odd plate-like structures with several filaments arising have no precedent among birds or theropods, nor do they conform to any of the hypothetical feather morphologies conceived by developmental biologists who study feather origins. As a note of caution, reptiles in general are known to do many odd things with their skin – many produce armour within the skin and the variety of scale form and function among living reptiles is enormous, ranging from the flat, horny scutes of turtle shells, to the thin scales of snakes, and the long fringing scales of iguanas, as well as the feathers and protofeathers seen in birds and theropods. Even among other extinct reptiles, we have the bizarre elongate scales of Longisquama, the elaborate midline crests of hadrosaurs and the fuzzy pycnofibres of pterosaurs to show us that lots of experimentation was going on with epidermal and dermal structures and their derivatives. So, are the structures in Kulindadromeus feathers, a side branch of the feather story, or were they an independent invention of a novel skin covering, as has occurred many times in the evolutionary history of reptiles? Indeed, a rival team working on other material from the same locality concluded that these features were ‘bristle-like scales’ (Saveliev and Alifanov 2014).

Personally, I think the jury is still out on this and that some of the enthusiastic responses to the announcement of Kulidadromeus may prove to be premature. Questions remain over the detailed morphology of these structures and their composition. Also, the authors conducted no analyses to support their claim that the discovery of these features in Kulindadromeus affects our overall picture of dinosaur skin evolution. Discovery of beta-keratin and of features identical to those seen in theropods would help to cement the case for feather-like structures in Kulindadromeus, but what we really need to solve the mystery of ornithischian feathers once and for all are older fossil deposits that have the potential for the exceptional preservation of skin structures. This would enable us to see how deep these features really go, but unfortunately these deposits remain elusive, at least at present.

References

Godefroit, P. et al. 2014. A Jurassic ornithischian dinosaur from Siberia with both feathers and scales. Science 345, 451–455. (doi:10.1126/science.1253351)

Norell, M. A. &  Xu, X. 2005. Feathered dinosaurs. Annual Reviews of Earth and Planetary Science 33, 277–299. (doi:10.1146/annurev.earth.33.092203.122511) 

Saveliev, S. V. & Alifanov, V. R. 2014. A new type of skin derivatives in ornithischian dinosaurs from the Late Jurassic of Transbaikalia (Russia). Doklady Biological Sciences 456, 182–184.

Zheng, X-T. et al. 2009. An Early Cretaceous heterodontosaurid dinosaur with filamentous integumentary structures. Nature 458, 333–336. (doi:10.1038/nature07856)å