New Species of Psittacosaurus Named and Described

Psittacosaurus may not be as well known as later ceratopsians such as Triceratops (horned dinosaurs), but for this genus of dinosaur it has an important place in palaeontology, simply because it is the most species diverse of all the known dinosaur genera.

Psittacosaurus

Now a new species of Psittacosaurus or “parrot lizard” has been named and described – Psittacosaurus gobiensis, making this, in our estimation the ninth type of Psittacosaur to be named and described to date.  Once regarded as an ornithopod, psittacosaurs are now believed to be a transitional form between Ornithopoda and the ceratopsians, fossils of these particular dinosaurs are associated with Asia, most famously the Gobi desert region.  Although small by dinosaur standards, with the largest species a little over 2 metres long, the numerous fossils found to date have provided scientists with a wealth of data on the evolution and behaviour of these Cretaceous animals.

In recent years some remarkable fossils associated with this genus have been discovered.  For example, remains of a group of baby Psittacosaurs were found together, perhaps evidence of herding or flocking behaviour.

To read more about this discovery: Dinosaur Nursery Unearthed in China.

Feathered theropods are known from the fossil record, but another fossil specimen of a Psittacosaurus from Liaoning (China) indicates that these ornithischians may have had feathers too, at least according to a Chinese scientific paper published recently in the journal Nature.

To read about feathered Psittacosaurs: Feathered Ornithopods upset the Scientific Apple Cart.

An Illustration of a Feathered Psittacosaurus

A model of the dinosaur called Psittacosaurus. Picture credit: Everything Dinosaur

Picture credit: Everything Dinosaur

Psittacosaurus was named “parrot lizard” after its parrot-like beak, this little dinosaur was a low browser, perhaps adapted to feeding on the fruits and nuts of angiosperms (flowering plants).  It had long hind legs and was capable of adopting a bipedal stance if required and some fossils indicate that it had long, quills running down its back and along its tail (as illustrated above).  Psittacosaurs are associated with Cretaceous strata, P. gobiensis for example, has been dated to approximately 112 million years ago (Aptian faunal stage).

Scientific Paper

In a paper on this new type of dinosaur, P. gobiensis, this one-metre-long dinosaur, may have had a diet dominated by nuts and seeds and this specimen is associated with gastroliths (stomach stones) which may reinforce the high fibre diet theory.  The paper on this dinosaur has been published in the Proceedings of the Royal Society B: Biological Sciences.

Picture show the skull of P. gobiensis compared to a the skull of a modern parrot (Macaw).  Analysis of the skull of this new psittacosaur indicates that this animal chewed its food in a similar way to parrots.

Professor Paul Sereno, from the University of Chicago commented:

“These and other features, along with the presence of numerous large stomach stones, suggest that psittacosaurs may have had a high-fibre, nut eating diet”.

“Parrot Lizard”

The short snout, just a third of the skull length was different to most dinosaurs, giving the skull its parrot-esque profile.

Professor Sereno went on to add:

“Psittacosaurs are all relatively small in body size, ranging from one to two metres in body length.  Their geographic range is limited to central Asia, and their temporal range may be as narrow as 10-20 million years in the mid Cretaceous”.

The head is rather square looking in profile, which along with the heavy beak makes the skull resemble a parrot’s .  There are no teeth in the front of the jaw but robust teeth further to the back of the jaws are blunt and designed for chopping and crushing.

To view models of ornithopods, ceratopsians and psittacosaurs visit the models section of the award-winning Everything Dinosaur website: Dinosaur and Prehistoric Animal Models.

New Research Questions “Birds Descended from Dinosaurs Theory”

For some time the theory that theropod dinosaurs gave rise to birds has been an accepted part of scientific thinking, a hypothesis that is largely believed by the majority of palaeontologists and academics.  However, the exact relationship between Dinosauria and the Aves has to be determined.  There are certainly enough common anatomical similarities to indicate an evolutionary relationship, but whether or not birds actually are the descendants of small, bipedal meat-eating dinosaurs has been questioned on numerous occasions.

Newly Published Research

A new research paper published in the scientific publication “The Journal of Morphology” provides a new perspective on this problem, one that was debated as long ago as the 1880s by eminent British scientists such as Huxley.

That birds may be the descendants of dinosaurs is perhaps of the most strongly accepted hypotheses in current evolutionary research.  However, there is mounting evidence to suggest that the theory is simply not right, the interpretation of the relationship may be wrong and evidence has been published by the Oregon State University in the United States that asks scientists to reassess the dinosaur-bird link.

Because of the demands associated with powered flight, birds have a very unique physiology.  Birds breathe very differently from mammals and reptiles.  Their lungs are particularly efficient and have a circulation system that does not permit oxygenated air to mix with de-oxygenated air.  These lungs are much more efficient than the lungs of a cold-blooded reptile such as a crocodile for example.

To read more about the structure of Avian lungs: Ideas on Dinosaur Breathing – A Breathe of Fresh Air.

In addition to very efficient lungs, birds have an immobile thigh bone. The locked femur has been known for some time, but the role it actually plays in aiding flight is the subject the new discovery from the Oregon University based team.  The researchers found that there is a strong relationship between the immobile femur (thigh bone) and the air-sac structure of the lungs.

The researchers state there is a strong relationship between:

“the fixed position of bird bones and musculature that keeps their air-sac lung from collapsing when the bird inhales”.

An immobile femur is unique to birds, it is not seen in other vertebrates.   According to Oregon State University’s John Ruben (Professor of Zoology) this work on the link between the femur and the lung structure may indicate that birds evolved alongside dinosaurs in the Mesozoic not directly from a specific SuperOrder such as Theropoda.

He stated that:

“This discovery probably means that birds evolved on a parallel path alongside dinosaurs, starting that process before most dinosaur species even existed”.

Theropod Dinosaurs

Understanding the lung function of dinosaurs is crucial in establishing the relationship between Aves and the Dinosauria.  However, the lack of fossil evidence (limited soft tissue preserved), has prevented scientists from making progress in this particular field of research.   Perhaps, the mummified hadrosaurine known as “Dakota” which seems to have a lot of soft tissue preserved may provide more data.  This new research from the American team, challenges the accepted, current theory.  Anatomical evidence from dinosaur fossil bones supports the theory that theropods had a mobile femur and as a result their lungs would have to be very differently structured to those of a bird.

Professor Ruben commented:

“Theropod dinosaurs had a moving femur and therefore could not have had a lung that worked like that in birds.  Their abdominal air sac, if they had one, would have collapsed”.

The question arises therefore, that if birds did not descend from theropods, then where did they come from?  There is evidence of birds in the fossil record from the post Callovian/Oxfordian faunal stages (Archaeopteryx lithographica), but there are very few fossils of birds in the known fossil record, even including those remarkable fossils from Liaoning Province in China.  If birds are not really feathered, flying theropods then this theory from the American team would suggest that they are still related and that they evolved from a common ancestor – the reptilian thecodonts (Thecodontia).

Everything Dinosaur stocks a wide range of theropod dinosaur models including: Papo Dinosaurs.

The dinosaur-bird link will remain controversial and be debated for many years to come, until some of the new technology including genetic research provides more information about known fossils or a new fossil is found to provide a fresh perspective.