Blogozoic

Field trip to the Otways

Another post, another field trip! I’ve been quite fortunate so far this year, this trip was my third already and it’s only March (I think my fiancé has forgotten who I am)! In my defence though, this trip was only a short two night stay, with a day and a half worth of field work.

But enough already, where did I go? The locality we were digging at is known as Eric the Red West and it is situated on the southern coast of Victoria’s Otways ranges, around four hours west of Melbourne. The name of the site comes from a famous ship known as Eric the Red that wrecked there in 1880, whose anchor lies just east of our dig site, hence the Eric the Red West! The rocks at this locality are similar to those found at the site of my last field trip at Flat Rocks, Inverloch, which is on the other side of Melbourne. However the rocks in the Otways, although also Early Cretaceous, are around 10 million years younger than those found at Inverloch. They would have once been part of the same single unit but geological events in the Miocene have split them into two separate groups. The fossils found from the Otways are from the Eumarella Formation, Otways Group and the Flat Rocks fossils are from the Wonthaggi Formation, Strzelecki Group (Benson et al., 2012). This temporal difference between the two areas gives us a unique opportunity to study the evolution of life here in Victoria during the early Cretaceous as we can compare the two sites and look for differences in the flora and fauna.

Map showing not only the Eric the Red West site and the Flat Rocks site at Inverloch, but other fossil localites from Victoria. Image from Benson et al., 2012.
Map showing not only the Eric the Red West site and the Flat Rocks site at Inverloch, but other fossil localities from Victoria. Image from Benson et al., 2012.

Another bonus of a field trip to the Otways is the camp we get to stay in. Called Bimbi Park, it is situated right in the middle of the Otways Ranges National Park (so no Internet, hence the lateness of this blog post) where you are surrounded by trees full of Koalas, although at night when you’re trying to sleep and the males won’t stop bellowing they can lose their appeal momentarily! It really is a beautiful picturesque spot for getting away from it all and I’d definitely recommend it should you ever find yourself in that neck of the woods.

Picture of the campsite at Bimbi park. You really do get to sleep with Koalas above your head! Image from planbooktravel.com
Picture of the campsite at Bimbi park. You really do get to sleep with Koalas above your head! Image from planbooktravel.com

Tourism plugs aside, there have been several notable finds at the Eric the Red West site since it was first prospected in 2005 (Kool, 2010). There tends to be fewer finds at the Otways site, but the material is often of better quality than Flat Rocks. One of the best came on that very first day of prospecting when an articulated tail and complete right foot of a small ornithopod dinosaur was discovered. In 2006 Inverloch and Otways dig stalwart Mary Walters found a mammal jaw (not her first one either) and more recently, dig regular Alanna Maguire has found the first upper mammal jaw from the Cretaceous of Australia (something that is still being researched at present).

The mammal jaw Mary Walters found at the Eric the Red West site in 2006, prompting an annual field season there every year since. Image from the 2007 Dinosaur Dreaming Field Report.
The mammal jaw Mary Walters found at the Eric the Red West site in 2006, prompting an annual field season there every year since onwards. Image from the 2007 Dinosaur Dreaming Field Report.

This field season is proving to be a very profitable one with the record for number of bones found in one day at the site being broken on the Monday I was there, and just prior to writing this post I read (via the Dinosaur Dreaming blog) that they had found two ornithopod jaws! There are some very exciting fossil layers being chased into the rock at present and hopefully they keep finding more cool stuff!

Now, where should I go for my next field trip…?

References

Benson, RBJ, Rich, TH, Vickers-Rich, P, Hall, M (2012) Theropod Fauna from Southern Australia Indicates High Polar Diversity and Climate-Driven Dinosaur Provinciality. PLOS One 7(5): e37122. doi:10.1371/journal.pone.0037122.

Kool, L (2010) Dinosaur Dreaming. Exploring the Bass Coast of Victoria. New Artworx, Melbourne. 95pp.

Ukrainian fossil giant salamander provides new insights into group’s origins

Amphibians are perhaps one of the less popular tetrapod groups. Most people would rather look at a furry mammal or feathered bird than a slimy newt or toad. This doesn’t mean that the group, consisting of frogs, toads, salamanders and the limbless caecilians, aren’t interesting. In fact, the first vertebrates that made the transition to life on land some 370 million years ago were amphibians so we all owe a debt of gratitude to our moist-skinned cousins! Since then, they have continued to successfully adapt and survive, with around 7,000 species alive today. The largest amphibians in the world today are the Chinese giant salamander (Andrias davidianus) and the Japanese giant salamander (Andrias japonicas), which can reach lengths of over 1.5 m. In the video below (narrated by the one and only, legendary, awesome and über-cool David Attenborough) you can see how amazing these animals really are and why they should maybe get more attention than they do.

But what is even cooler than giant salamanders? Fossil giant salamanders of course! And a new paper by Vasilyan et al. published in the most recent issue of the Journal of Vertebrate Paleontology has just described a new species of giant salamander from Ukraine and revealed new insights into the origins of the group (known scientifically as Cryptobranchids). The new species, Ukrainurus hypsognathus is middle-late Miocene in age (around 11.5 million years) and was found in an abandoned quarry just southeast of the village of Grytsiv, western Ukraine. The holotype is a left dentary (shown below) and other cranial elements and several postcranial elements have also been assigned to the same individual.

The holotype dentary of Ukrainurus hypsognathus shown in A, lingual; B, dorsal; C, labial; D, ventral views. Scale bar = 1 cm. Image from Vasilyan et al. 2013.
The holotype dentary of Ukrainurus hypsognathus shown in A, lingual; B, dorsal; C, labial; D, ventral views. Scale bar = 1 cm. Image from Vasilyan et al. 2013.

By studying the dentary and other cranial elements of U. hypsognathus, Vasilyan et al. were able to establish that it would have had a considerably strong bite force, with which it would have used to feed on prey such as fish, frogs and even other salamander species that are also known from the locality. They also found that the jaw of U. hypsognathus would have been less flexible than that of modern giant salamander species, meaning its method of prey capture may have differed slightly from that of modern taxa.

The phylogeny of Vasilyan et al. 2013. You can see that Ukrainurus hypsognathus is sister to all crown Cryptobranchids. Image from Vasilyan et al. 2013.
The phylogeny of Vasilyan et al. 2013. You can see that Ukrainurus hypsognathus is sister to all crown Cryptobranchids. Image from Vasilyan et al. 2013.

This paper is also the first study in which the relationships between fossil and recent species of giant salamanders have been analysed in a phylogenetic context. The results of the phylogenetic analysis show that U. hypsognathus is the sister taxon to crown group Cryptobranchidae. The single living American species Cryptobranchus alleganiensis was also found to be the sister taxon of all Eurasian cryptobranchids. A fossil cryptobranchid from Saskatchewan, Canada (excluded from the final phylogenetic analysis) was found not to be closely related to C. alleganiensis, but would have placed more basally in the phylogeny, closer to U. hypsognathus.

What this all implies is that Cryptobranchidae originated in Asia and dispersed to North America on two separate occasions. In terms of the timing of these events, the oldest crown Cryptobranchid is Aviturus exsecratus from the Palaeocene of Mongolia. This means that the split between crown and stem Cryptobranchidae would have had to occur in the Palaeocene at the latest and possibly even in the Late Cretaceous. When exactly the C. saskatchewanensis and C. alleganiensis lineages dispersed to America remains uncertain however.

With the majority of fossil cryptobranchids being known from Central rather than Eastern Europe, it would appear that there could well be more new insights to come on the evolution of the giant salamanders, surely an interesting group of amphibians if there ever was one.

Reference

Davit Vasilyan , Madelaine Böhme , Viacheslav M. Chkhikvadze , Yuriy A. Semenov & Walter G. Joyce (2013): A new giant salamander (Urodela, Pancryptobrancha) from the Miocene of Eastern Europe (Grytsiv, Ukraine), Journal of Vertebrate Paleontology, 33:2, 301-318.         

Getting inside the head of a fuxianhuiid

If you were to look at the diversity of life on Earth today, you could be forgiven for thinking that animals have always been around and have dominated the planet since time memorial. However, you would in fact be completely wrong! Animals have only been around for roughly 600 million years whilst life first evolved over 3.5 billion years ago and remained in single-celled form for the majority of the Earth’s history.

The period when animals rapidly diversified into the majority of extant phyla is known as the ‘Cambrian explosion’, which began approximately 545 million years ago during the Cambrian period. One particularly enigmatic example of this is the Burgess Shale, where beautifully preserved animals, some of which are unlike anything alive today, have been found.

This odd looking creature is Opabinia, one of the enigmatic products of the Cambrian explosion. It possessed five eyes which were on stalks, and a long proboscis which it used to grab its food! Image from paleobiology.si.edu
This odd-looking creature is Opabinia, one of the enigmatic animals of the Burgess Shale. It possessed five eyes which were on stalks, and a long proboscis which it used to grab its food! Image from paleobiology.si.edu

Until the past few decades, the Burgess Shale has stood out as our best glimpse into this stage of the evolution of life on Earth. However in China, several localities (e.g. Chengjiang) have been found, producing fossils of equally exquisite detail which scientists have been excitedly studying. The advantages of localities like these is that we can decipher how living groups first evolved and what would most likely have been the ancestral state for our modern animal groups.

Two new fossil species, described this past week in the journal Nature give us just such an insight for arthropods, the group containing animals such as insects, crustaceans, centipedes, spiders and the extinct trilobites. The fossils, named as Chengjiangocaris kunmingensis and Fuxianhuia xiaoshibaensis are from a group known as the fuxianhuiids, which are regarded as representatives of early arthropods.

Chengjiangocaris kunmingensis, the image on the left shows a reconstruction of the animal with the feeding tube and nerve cord shown running the length of the animal. The image on the right shows a specimen with the head 'taphonomically dissected', allowing the researchers to see the limbs and nerve cord properly for the first time. Images from Yang et al. 2013.
Chengjiangocaris kunmingensis, the image on the left shows a reconstruction of the animal with the limbs shown on the head of the animal and the feeding tube and nerve cord shown running the length of the animal. The image on the right shows a specimen with the head shield ‘taphonomically dissected’, allowing the researchers to see the limbs and nerve cord properly for the first time. Images from Yang et al. 2013.

The fossils, which were found in a Lagerstätte (a locality of exceptional preservation) near the city of Kunming in the Yunnan province of China, have been dated to approximately 520 million years old, meaning they are from a relatively early stage of the ‘Cambrian explosion’. Previous specimens of fuxianhuiids have had their heads covered by their head shield, part of the tough exoskeleton that is synonymous with arthropods. This has meant that debate over what exactly the paired post-antennal structures in other fuxianhuiids actually represented has never had a clear resolution. Until now that it is. In a stroke of geological good fortune, numerous specimens of the two new fuxianhuiid species have experienced ‘taphonomic dissections’, where the conncective tissues of the head shield have softened before final burial allowing the head shields to rotate forwards, exposing the structures underneath and making them visible to scientists for the first time.

The holotype specimen of Fuxianhuia xiaoshibaensis. At the top of the image you can see where the head shield has rotated forward, revealing the structures underneath. Image from Yang et al. 2013.
The holotype specimen of Fuxianhuia xiaoshibaensis. At the top of the image you can see where the head shield has rotated forward, revealing the structures underneath. Image from Yang et al. 2013.

The fossils are so well-preserved that the functional articulation of these post-antennal structures can be explained. The limited range of movement in the limbs means that they would most likely have been used to sweep detritus into the mouth, where the food particles would then have been filtered out of it.  The nerve cord is also the first documented
case of a preserved post-cephalic central nervous system in a stem group arthropod. It is simple in structure, especially compared to animals alive today (perhaps as expected).

The locality these fossils were found has just begun to be explored. With the potential for more insights into this pivotal period in the evolution of life and finds with this quality of preservation, I could very well be writing more articles on invertebrates sooner than I think!

References

Jie Yang, Javier Ortega-Hernández, Nicholas J. Butterfield, Xi-guang Zhang. Specialized appendages in fuxianhuiids and the head organization of early euarthropods. Nature, 2013; 494 (7438).

Field trip to Flat Rocks, Inverloch

For the past week I’ve been at a dinosaur dig I’ve been fortunate enough to attend every February since 2010. The dig, jointly organised by Monash University and Museum Victoria, is known as Dinosaur Dreaming and has been running every summer for the past 20 years, making it potentially the longest running dinosaur dig in the world!

The Dinosaur Dreaming site is approx. 113 km SE of Melbourne and has yielded numerous fossils for the past two decades. Image from Google maps.
The Dinosaur Dreaming site is approx. 113 km SE of Melbourne and has yielded numerous fossils for the past two decades. Image from Google Earth.

The locality is dated as Aptian (Early Cretaceous, ~120 Ma) and represents a a floodplain that existed in the rift valley formed by the gradual separation of Antarctica and Australia, a process that wasn’t completed until over 80 million years later. The supercontinent that these two continents formed part of (along with South America, Africa and India) was known as Gondwana. The fossils are found in layers in the light grey sandstone and conglomerate, along with abundant coal, fossilised tree stumps and other plant material. It is believed that the fossil material would have been swept in from locations upriver during episodes of flooding that caused the main rivers nearby to burst their banks. These fossil layers are what we look for when we dig at this site. It usually means having to clear off a sizeable amount of sand each morning to reaccess the fossil layer! Once we’ve cleared off the overburden a few crew members then use sledgehammers to break large chunks of rock out of the ground which is then passed to other crew members who break it down into sugar cube sized pieces searching for the fossils within.

Yours truly examining a rock to see if there any fossils inside. I almost look like I know what I'm doing! Image by Darren Hastie.
Yours truly examining a rock to see if there any fossils inside. I almost look like I know what I’m doing! Image by Darren Hastie.

And what type of fossils are we looking for exactly? Well, so far finds have included: dinosaurs (ornithopod and theropod), mammals, turtles, freshwater plesiosaurs, pterosaurs and fish, giving us a reasonably good idea of what made up this Early Cretaceous ecosystem. The downside is however that, as the material has been swept in by flooding, it is very rarely that complete elements are found (although keep your eyes peeled at the end of 2013/start of 2014 for something truly amazing coming from the site…). It is much more common to find small fragments of fossils that researchers then have to use all of their experience to piece the animal back together again, both literally and figuratively!

Another plus about the dig is that it provides school children from right across the state the chance to come and see what a real life dinosaur dig looks like (I wish I had that when I was a kid), they even get the chance to have a look for some fossils themselves!

The dig has its very own blog too, which keeps the public up to date with the goings on of the dig and what the diggers get up to during the rest of the year. Check out this video on the dinosaur dreaming blog, which shows the dig site and what we do, it even includes a short appearance by yours truly right at the end!

A massive thank you must go to Lesley, Gerry, Dave, Wendy, John and Lisa for all their hard work in keeping the dig going for as long as they have, hopefully it can last another 20 years!

 

The Lark Quarry Trackway: Thulborn Strikes Back

UPDATE: I made a slight mix up when writing this article last week. I have stated that Thulborn, 2013 is responding to the claims of Romilio et al. 2012. This is actually incorrect. The paper to which Thulborn is responding is Romilio and Salisbury, 2011, where they dispute the identity of the large track maker at Lark Quarry and its consequences for the interpretation of the trackway. Thulborn has not yet responded to the new claims in Romilio et al. 2013, although he may do so in future. The core message of the article however is still the same. Romilio et al. do not believe that the trackway at Lark Quarry represents a dinosaur stampede, whereas Thulborn maintains it does. This intriguing topic will no doubt continue to provide ample material for debate in the years to come. This article has been edited from its original and second versions. For anyone who wants to see the original version, email me at the address at the top of the blog.

Regular readers of this blog (if there is such a thing) may recall that I wrote an article about a new paper by Romilio & Salisbury where they disputed the claims made by Tony Thulborn, who stated that the dinosaur trackways at Lark Quarry, Queensland were made by stampeding dinosaurs. In their paper they proposed that in fact the trackways were made at different times and showed dinosaurs crossing a river.

Perhaps a stampede after all? Thulborn certainly still seems to think so. Image from abc.net.au.
Perhaps a stampede after all? Thulborn certainly still seems to think so. Image from abc.net.au.

Now, Thulborn has responded to the claims made by Romilio & Salisbury, 2011, rejecting their analysis. In his rebuttal, Thulborn criticises their application of the multivariate analysis method, pointing out that they didn’t actually compare trackways of ornithopods and theropods but rather studied a single trackway, meaning that the only variation they could obtain would be between the individual tracks themselves. He also states that the multivariate analysis “appears to be based on fabricated data and is, therefore, worthless”.  The outlines of these tracks would have also deteriorated over time (Thulborn and Wade, 1984).

Thulborn also takes issue with how Romilio et al. have portrayed Thulborn’s initial interpretation of the site as a prey-pursuit scenario. Thulborn makes the distinction that he has never said it was this particular scenario (except when explicitly speculating), but rather that it was merely a stampede in general, regardless of the identity of the large track maker. Indeed, he argues that the whole premise of the recent paper by Romilio et al. seems to be to declare the larger tracks were in fact made by a large ornithopod, a fact that Thulborn declares is a “separate matter of secondary interest”.

So is the trackway at Lark Quarry evidence of a dinosaur stampede or not? Well, it depends on who you ask at the moment! Further study will no doubt show which of the two parties were closest to being correct. This debate is sure to continue; I’ll keep you all updated when the next developments arise!

References

Romilio A, S. W. Salisbury (2011) A reassessment of large theropod dinosaur tracks from the mid-Cretaceous (late
Albian-Cenomanian) Winton Formation of Lark Quarry, central-western
Queensland, Australia: A case for mistaken identity. Cretaceous research 32: 135-142.

Romilio A, Tucker, R. T. and S. W. Salisbury (2013): Reevaluation of the Lark Quarry dinosaur Tracksite (late Albian–Cenomanian Winton Formation, central-western Queensland, Australia): no longer a stampede?, Journal of Vertebrate Paleontology, 33:1, 102-120.

Thulborn, R.A. (2013): Lark Quarry revisited: a critique of methods used to identify a large
dinosaurian track-maker in the Winton Formation (Albian–Cenomanian), western Queensland, Australia, Alcheringa: An
Australasian Journal of Palaeontology, DOI:10.1080/03115518.2013.748482

Thulborn, R. A., and M. Wade. 1984. Dinosaur trackways in the Winton
Formation (mid-Cretaceous) of Queensland. Memoirs Queensland
Museum 21:413–517.

The Dromornithids: An Introduction

Australia has been separated from the rest of the world for the majority of the last 65 million years, with complete separation occurring around 30 million years ago. This has given the various forms of life on the continent plenty of time to evolve into their own unique groups. One particularly fascinating and enigmatic group is the family of extinct, giant flightless birds known as the dromornithids.

A reconstruction of Dromornis stirtoni by the fantastic palaeo-artist Peter Trusler. In this image they have been reconstructed as herbivores.
A reconstruction of Dromornis stirtoni by the fantastic palaeo-artist Peter Trusler. In this image they have been reconstructed as herbivores.

Australia today is famous for a group of flightless birds known as the emus; and for a long time the dromornithids were believed to be members of the same group of birds (the ratites). However, in 1998 a study by Murray and Megirian demonstrated that dromornithids are in fact neognathous birds in the Anseriformes. Nonetheless, it remains debatable as to which anseriform group is sister to the dromornithids (Murray & Vickers-Rich 2004, Olson 2005, Agnolin 2007). With a fossil record spanning around 25 million years, dromornithids are known from the late Oligocene through to the late Pleistocene (Field & Boles 1998, Nguyen et al. 2010). An ancient origin for the group is implied by a possible dromornithid foot impression from the early Eocene (approx. 50 million years ago) of Queensland (Vickers-Rich and Molnar 1996). Following an overdue taxonomic revision of the Dromornithidae (Nguyen et al. 2010), the family includes seven accepted species in four genera, with a geographic distribution including every state in Australia. The largest species, Dromornis stirtoni, is estimated to have stood at 3 m tall and weighed up to 500 kg, potentially even larger than the famous elephant bird of Madagascar.

A skeletal reconstruction of Dromornis stirtoni with human for scale showing just how big these animals could have been. Image from www.carnivoraforum.com.
A skeletal reconstruction of Dromornis stirtoni with human for scale showing just how big these animals could have been. Image from http://www.carnivoraforum.com.

There has been some debate as to whether the dromornithids were herbivorous or carnivorous, with features of the skull hinting at the potential for either way of life. Skull material is not known from every species however, and all members of the group may not have shared the same feeding ecology. Gizzard stones have been found in association with dromornithid remains, suggesting they needed the stones to help process plant material, although carnivores such as crocodiles are also known to possess them.

The dromornithids went extinct in the late Pleistocene and it is still unclear what combination of human hunting, landscape changing or climate change was the ultimate cause of their demise.

This is another Peter Trusler reconstruction, this time of the late Pleistocene species Genyornis newtoni. This species could well have encountered the first humans to arrive in Australia, but were they the cause of their extinction?
This is another Peter Trusler reconstruction, this time of the late Pleistocene species Genyornis newtoni. This species could well have encountered the first humans to arrive in Australia, but were they the cause of their extinction? Image from Museum Victoria.

I have also had a personal interest in the dromornithids as myself and Dr. Erich Fitzgerald published a short paper on the Dromornithids last year (Park and Fitzgerald, 2012). In it we detailed the oldest known occurrence of the dromornithids in Victoria, a poorly preserved partial tarsometatarsus (one of the bones in the legs of birds). This bone appeared to represent a new species as it could not be referred to any of the known taxa elsewhere in Australia. Previously, the earliest known dromornithids in Victoria were from the late Pleistocene ( approx. 30,000 years ago) Lancefield Swamp locality, so this find pushes their presence in Victoria back in time considerably. It also cautions against deriving evolutionary patterns solely on the basis of fossils from northern Australia.

The dromornithids as a group still retain a lot of mystery and unanswered questions, and are long overdue for a thorough reanalysis. In fact, one of my colleagues plans to do exactly that over the next few years and I for one look forward to seeing what new details he can reveal about these ‘magnificent Mihirungs’.

References

AGNOLIN, F.L., 2007. Brontornis burmeisteri Moreno & Mercerat, un Anseriformes (Aves) gigante del Mioceno medio de
Patagonia, Argentina. Revista del Museo Argentino de Ciencias Naturales 9, 15–25.

FIELD, J.H. & BOLES, W.E., 1998. Genyornis newtoni and Dromaius novaehollandiae at 30,000 b.p. in central northern New South Wales. Alcheringa 22, 177–188.

MURRAY, P.F. & MEGIRIAN, D., 1998. The skull of dromornithid birds: anatomical evidence for their relationship to Anseriformes. Records of the South Australian Museum 31, 51–97.

MURRAY, P.F. & VICKERS-RICH, P., 2004. Magnificent Mihirungs: the Colossal Flightless Birds of the Australian Dreamtime. Indiana University Press, Bloomington, 410 pp.

NGUYEN, J.M.T., BOLES, W.E. & HAND, S.J., 2010. New material of Barawertornis tedfordi, a dromornithid bird from the Oligo- Miocene of Australia, and its phylogenetic implications. Records of the Australian Museum 62, 45–60.

OLSON, S.L., 2005. Review of Magnificent Mihirungs: the Colossal Flightless Birds of the Australian Dreamtime. The Auk 122, 367–371.

Travis Park & Erich M. G. Fitzgerald (2012): A late Miocene–early Pliocene Mihirung bird (Aves: Dromornithidae) from Victoria, southeast Australia, Alcheringa: An Australasian Journal of Palaeontology, 36:3, 419-422.

VICKERS-RICH, P. & MOLNAR, R.E., 1996. The foot of a bird from the Eocene Redbank Plains Formation of Queensland, Australia. Alcheringa 20, 21–29.

Baby fossils shed new light on Oviraptorid feeding habits

Oviraptorids are not your usual type of theropod dinosaur. Most people assume that all theropods had jaws bristling with teeth like steak knives ready to eviscerate the next hapless victim they came across, but Oviraptorids actually possessed short deep skulls and toothless jaws. These beaks were initially thought to have been used to crush eggs (the name Oviraptor literally means ‘egg-thief’). When the first Oviraptorid fossil was found in 1924 (Oviraptor philoceratops, Osborn, 1924) it was alongside a nest of what were thought to be Protoceratops eggs, with the Oviraptorid being assumed to be trying to grab a meal. It wasn’t until 1999 (Clarke et al. 1999) and the discovery of a closely related species (Citipati osmolskae) brooding its eggs that it was realised that Oviraptor was more likely caring for its unborn offspring rather than securing its dinner.

This is the manner in which Oviraptorids used to be portayed, as egg thiefs rather than caring parents. Notice the very out of date posture, lack of feathers and horn instead of a crest. Image from midgetonfire.blogspot.com.
This is the manner in which Oviraptorids used to be portayed, i.e. as egg thieves rather than caring parents. Notice the very out of date posture, lack of feathers and horn instead of a crest. Image from midgetonfire.blogspot.com.
The more contemporary view of Oviraptorids. Citipati is shown here brooding on its nest of eggs in a pose that you can still see today in living birds. Image from Clark et al. 1999.
The more contemporary view of Oviraptorids. Citipati is shown here brooding on its nest of eggs, a pose that you can still see today in living birds. Image from Clark et al. 1999.

So what exactly did Oviraptorids eat? Were they herbivores, carnivores or omnivores? These questions are still the subject of some debate by palaeontologists. A new paper, published in the German journal Naturwissenschaften may have discovered new evidence to help sway the argument one way or another.  The paper, by Lu et al., describes a new species of Oviraptorid, Yulong mini and compares it to all known Oviraptorids and other theropods.

Baby dinosaur! This is the juvenile skeleton of Yunlong mini, as well as a line drawing to help you decipher which bones are which. Image from Lu et al., 2013.
Baby dinosaur! This is the juvenile skeleton of Yunlong mini, as well as a line drawing to help you decipher which bones are which. Image from Lu et al., 2013.

When the authors analysed the results of their comparisons, they noticed that the hind limb proportions of Oviraptorids remain constant throughout their whole lives. This is different to most theropods, whose hind limb proportions tend to change as they mature (allometric growth). The interesting thing is that this type of growth (known as isometric) tends to be found in is herbivores. Furthermore, although the individuals found were less than a year old, their limb bones were quite well developed, suggesting they were already able to move around easily. If you couple this with the lack of adult skeletons found at the localites Yulong was discovered, there may be a case for Yunlong possessing precocial development (i.e little/no parental care, effectively born like a mini adult), something again associated with herbivores. Carnivores tend to be altricial, where they are born relatively helpless and require more care take longer to develop.

So was Yunlong and other Oviraptorids herbivorous? We still don’t know for sure. But this new evidence suggests it remains a distinct possibility.

References

Clark, J.M., Norell, M.A., & Chiappe, L.M. (1999). “An oviraptorid skeleton from the Late Cretaceous of Ukhaa Tolgod, Mongolia, preserved in an avianlike brooding position over an oviraptorid nest.” American Museum Novitates, 3265: 36 pp., 15 figs.; (American Museum of Natural History) New York.

Lu, J, Currie, PJ, Xu, L, Zhang, X, Pu, H & Jia, S  (2013) Chicken-sized oviraptorid dinosaurs from central China and their ontogentic implications. Naturwissenschaften 100: 165-175.

Osborn, H.F. (1924). “Three new Theropoda, Protoceratops zone, central Mongolia.” American Museum Novitates, 144: 12 pp., 8 figs.; (American Museum of Natural History) New York.