New Chinese Feathered Dinosaur adds to Confusion over Evolution of Feathers

A paper published in the scientific journal “Nature” is ruffling a few feathers amongst palaeontologists as the authors postulate that bird-hipped dinosaurs had feathers too!  A team from the Shandong Tianyu Museum of Nature in China have reported on the discovery of a partial skeleton of a small, potentially bipedal dinosaur with feathers.  The fossil was found in the early Cretaceous sediments of the Liaoning Formation in north-eastern China.

The Evolution of Feathers

Feathered dinosaurs from Liaoning have been found before, the region is world famous for the remarkable fossils of feathered dinosaurs and birds that have been discovered.  These creatures drowned in a lake, sinking to the bottom and in most cases they were rapidly buried by fine volcanic ash without much disruption to their remains.  Several kinds of feathered saurischian dinosaurs are known from the Cretaceous sediments of this region, animals such as Sinosauropteryx and Sinornithosaurus for example.  However, there are a number of surprising features about this new discovery that have “ruffled a few feathers” according to an Everything Dinosaur spokesperson or alternatively, “has muddied the waters” in a similar comment made by a leading palaeontologist.

Firstly, although only part of this small dinosaur’s body has been fossilised, the Chinese team were able to identify limb bones, vertebrae, the hip girdle and most importantly the lower jaw and most of the lower and mid portions of the skull.  The animal has been identified as a member of the Heterodontosauridae, a very primitive ornithischian dinosaur, best known form Early Jurassic deposits from South Africa.

Heterodontosaurid Fossils

The heterodontosaurids are believed to be a basal group of the ornithischian dinosaurs and this is the first time that a fossil of such an animal has been found in China.  This specimen has been dated to the Early Cretaceous approximately 140 million years ago (Berriasian faunal stage).  This new fossil indicates that these dinosaurs, the heterodontosaurids, survived into the Cretaceous.  The heterodontosaurs are distinguished by their complex teeth.  The name Heterodontosauridae means”different-toothed lizards”, these little dinosaurs had remarkably advanced dentition.  Instead of the simple peg-like teeth seen in other herbivorous dinosaurs of the Early Jurassic this group had sharp, pointed, over sized canines and those teeth towards the back of the jaw were flatter and broad, designed for crushing plant matter.  It is thought that these dinosaurs may have been omnivores.  A general, non-specialised diet may be one reason why these little dog-sized dinosaurs persisted so long in the Mesozoic.

This information alone, would be enough to excite most scientists but for the Chinese specimen the fossil reveals an even more intriguing attribute – feathers.

Tianyulong confuciusi

The analysis of the dinosaur named Tianyulong confuciusi by the Chinese scientists has revealed the presence of primitive protofeathers along the back and front of the animal (dorsal and ventral areas).  Finding a new feathered dinosaur in Liaoning is not that remarkable given the fantastically rich fossil pedigree of the place, but a feathered ornithischian, that is a different matter.

The fossil found, represents a sub-adult, it was approximately 1 metre long with a long tail, most probably a bipedal stance and the wonderful heterodontosaurid dentition is very well preserved.  In the main slab of rock from which the fossil was extracted, the impression of long, filamentous, non-branched feather-like structures can be clearly seen.  Tianyulong has been reconstructed as an agile, swift running, mainly bipedal dinosaur that probably had an omnivorous diet catching insects as well as eating plant material.

A Model of the Newly Described Dinosaur Tianyulong confuciusi

A model of the recently described dinosaur Tianyulong.

The figure pictured above is a replica of Tianyulong by the Chinese manufacturer PNSO, to view the range of PNSO prehistoric animal figures in stock at Everything Dinosaur: PNSO Age of Dinosaurs Models.

The artist shows the long, filamentous feathers covering the back and the tail of this dinosaur, however, reference to the scientific report suggests that these long filaments are present along the back, chest and abdomen of this little dinosaur.  The artist has also chosen to portray Tianyulong as being covered in a coat of fine feathers, this is largely speculation as we understand that the one specimen found to date of this new type of dinosaur does not confirm that presence of a soft, downy coat.

One thing for sure, if this ornithischian dinosaur did have feathers, then it challenges sciences view on the evolution of modified scales (feathers) as most of the dinosaurs known to be feathered are theropod, saurischians.

Dinosaur Classification

Dinosaurs are classified into two major groups depending on the arrangement of the bones that comprise the hip girdle.

Dinosaurs are divided into two main orders: saurischians, which have forward-pointing pubic bones, and ornithischians, which have backward-pointing pubic bones.  The classification of the ornithischians and saurischians was first outlined in a scientific paper written by the British palaeontologist Harry Covier Seeley, over 120 years ago.  Seeley remarked on the similar types of pelvis certain dinosaurs had, he commented upon their “bird-like” features, as with modern birds the pubis bone at the front of the pelvis projected backwards.  With birds, this position of the pubis is believed to be related to efficient breathing enabling muscles to be oxygenated for flight.  However, with the ornithischians, it is believed the backward pointing pubis made room for a large gut – just what you need to digest tough vegetation, as most of the ornithischians known to date seem to be entirely vegetarian.

With a member of a basal ornithischian exhibiting protofeathers this throws into question the exact evolutionary origins of feathers.

Commenting on the find, Dr Phil Currie of the University of Alberta, Canada stated:

“The find pulls the origin of feathers down into the Triassic, when the saurischian and ornithischian lineages of dinosaurs split”.

The flight feathers on a bird are flexible, asymmetrical and have a central shaft with vanes that run off either side at angles, the feathers on T. confuciusi are all relatively stiff and lack vanes.

Hai-Lu You, one of the Chinese palaeontologists who described and named Tianyulong confuciusi, believes that the fossil supports the idea of a single evolution of feathers.

“We still have some missing data between T. confuciusi and feathered theropod dinosaurs, but I think further discovery will fill these gaps,” he commented.

Bird-hipped Dinosaurs

If this proves to be the case, then many dinosaurs may once have sported feather-like structures, with descendant species losing the characteristic.  The long, filamentous projections may have been used for display, perhaps to deter a rival or attract a mate.  If this dinosaur was covered in feathers then the evolution of feathers may have to be put into the Triassic and not the Jurassic.  Indeed, many other ornithischian dinosaurs may have possessed feathers, but their poor fossil preservation in many cases has prevented the feathers being recorded in the fossil record.

Pictures show the main slab of the fossil, the partial skull material can be seen in the top right of the picture and a limb and a foot can clearly be seen in the centre.

The white arrow in the picture is indicating the presence of long, filamentous, protofeathers, a trait rarely seen in ornithischian dinosaurs.  One of the few other examples of feather-like structures in “bird-hipped dinosaurs” is found in the Cretaceous, Asian dinosaur Psittacosaurus, which is believed to have possessed long, quill-like structures that stuck out from its tail.

Feathers on a Bird-hipped Dinosaur

The presence of feathers in a bird-hipped dinosaur may indicate that these animals were endothermic (warm-blooded).  This discovery, the genus named after the Shandong Tianyu Museum of Nature, where a number of the scientists are based, adds to our knowledge of feathered dinosaurs.  The species name is in honour of the ancient Chinese philosopher Confucius, as just like Confucius, this new dinosaur specimen will challenge conventional thinking.

This discovery may lead scientists to conclude that feathers were a primitive trait, that the common ancestor of both the saurischian and ornithischian groups possessed feathers.  Or did feathers evolve independently in the two groups?  Does this fossil indicate that ornithischian dinosaurs evolved feather-like structures independently of the evolution of the lizard-hipped theropods?  This could be an example of convergent evolution whereby two not too closely related animal groups evolve a common solution such as the development of feathers for insulation and display.

Canada’s Smallest Dinosaur Hints at Reptilian not Mammalian Predatory Niche

A research paper has just been published announcing the discovery of the smallest dinosaur known to date from North America.  This tiny theropod, identified from fossilised pelvic bones is believed to have been no bigger than a crow and probably lived in the undergrowth or up trees, filling a niche held by small mammals in today’s ecosystems.

Canadian Dinosaur

This new dinosaur species, remains of which come from the fossil rich sediments of Alberta, Canada, has been named Hesperonychus is believed to a close relative of the Chinese dinosaur Microraptor gui which some scientists claim is the smallest dinosaur discovered to date.

The tiny fossilised hip bones had been collected many years before, but they had been misidentified as being those from an extinct genus of lizard, it was only when the material was re-examined that the mistake was noticed.  The research paper on this tiny carnivore has just been published in the scientific journal “The Proceedings of National Academy of Sciences”.

This little dinosaur identified from a fused pelvic girdle (indicating an adult specimen, not a juvenile animal), is believed to be a member of the dromaeosaur family.  These bipedal dinosaurs were relatively common in the Late Cretaceous, but this particular member of the “swift lizards” is the smallest found in North America to date.  An examination of other fossil material has revealed some fossil finger and toe bones, including the retractable pedal ungual (toe claw), characteristic of the dromaeosaur group.

Pictures show the tiny Hesperonychus toe claw balanced on a Canadian coin for scale.  It is not known whether this small dinosaur would have been covered in feathers, but scientists have speculated that it probably was.  The feathers would have helped insulate this small meat-eater and help prevent it losing too much heat, regulating its body temperature.  They may also have helped it glide from tree to tree as it searched for food.

The specimen helps to confirm that reptiles, such as this tiny dinosaur and not mammals, filled the role of small predators during the Mesozoic.  There were certainly small mammals around at the time but they did not have a monopoly on the small, insect eating niche, perhaps dinosaurs like Hesperonychus hunted during the day and the mammals came out to hunt a night.

Dr Phillip Currie, palaeontologist from the University of Alberta and co-author of the research paper commented:

“Despite the discovery of exquisitely preserved skeletons of small bird-like dinosaurs in Asia, they are exceedingly rare in North America.”

Despite many major dinosaur finds in formations such as Judith River and the Dinosaur Provincial Park Formation, Dr Currie and his colleagues had been pondering why so few small fossils have been unearthed in Alberta, Canada – one of the world’s richest sites for large-dinosaur bones of the Cretaceous.  The team suspect that there were many small dinosaurs around during the age of reptiles, however, their remains did not preserve well so they are relatively scarce in the fossil record.

Dr Currie went onto state:

“There were many large dinosaurs running around eating them, and small bones are easily washed away by rivers [common in this region during the Cretaceous period]“.

The new discovery casts more doubt on whether mammals would have acted as small predators in Cretaceous-era North America. The fossilised pelvis came from an animal that weighed no more than 1.9kg (4.2lb) and appears distinctively reptilian.  Team members at Everything Dinosaur have had the opportunity to visit some of the fossil storage sites at Canadian museums such as the Royal Tyrrell Museum and we once calculated that there were so many fossils awaiting cleaning and study that it would take all the staff over 100 years to clear the back log.  Such is the rich diversity of fossils found in formations such as the Dinosaur Provincial Park, an ecosystem closely studied by Dr Currie and his fellow palaeontologists.

Commenting on the find, identified as an insect eating, bipedal, dinosaur, Dr Currie added:

“This tells us that [as in Asia], North American dinosaurs likely out-competed mammals for both large and small predator niches”.

The authors of the research also suggest that this little dinosaur may provide a clue to help resolve the debate as to whether flight originated in arboreal dinosaurs “tree down” or whether it evolved from dinosaurs that had a cursorial existence “ground up”.  Based on the size of the hip bones and the position of the pubis a bone that makes up the pelvic structure, normally this bone is to be found between the hind legs and with theropods it has in many cases a characteristic “boot” shape to the tip.  However, with Hesperonychus the pubis is bent, this indicates that it may have had an arboreal existence.

“We know this dinosaur was a tree-climber”, Dr Currie explained.

“It likely used the long feathers on its limbs to glide or parachute from tree to tree”.

Certainly, it would make sense if this little dinosaur was able to climb trees, it would have required an excellent sense of balance, strong limbs and stereoscopic sight, all qualities believed to have been possessed by Dromaeosaurs.  By climbing trees, it would have been able to catch insects and other invertebrates as well as avoiding many of the larger predators that shared its environment.

The scale of this little biped, is difficult to imagine, so the University of Calgary provided a diagram, illustrating the size of Hesperonychus in comparison with other contemporary theropods that also roamed Alberta at the time this little dinosaur existed.

Scale Drawing of Late Cretaceous Theropods from Alberta

Herperonychus had huge relatives.

Picture credit: University of Calgary/PNAS

Hesperonychus elizabethae

The specimen, Hesperonychus elizabethae – named after its collector Dr Elizabeth Nicholls – was reclassified by palaeontologist Dr Nicholas Longrich, a co-author of the paper, from the University of Calgary.

It has long been suspected that there were large numbers of small dinosaurs living in forest and woodland habitats, but forest environments have very poor fossil preservation potential and any small dinosaur remains on the forest floor would soon have been scavenged or broken up.  Hence, the fact that very small dinosaurs are probably under-represented in the existing fossil record.

Pliosaurs – Terrible Monsters of the Mesozoic Seas

A study into the potential bite force of an extinct marine reptile indicates that it was able to generate a force of around 15 Tonnes per square inch according to research information published by the Natural History Museum of Oslo.

The research summarises work done to date on newly discovered fossils of a pliosaur, an ancient marine reptile that would have terrorised the Jurassic seas and been an apex predator.

Short-necked Plesiosaurs

Pliosaurs are a short-necked variety of plesiosaur, instead of having small heads and long necks adapted to a diet of small prey items like the plesiosaurs, the pliosaurs evolved into the top predators of the Jurassic marine environment.  Pliosaurs had relatively massive skulls, armed with long, sharp teeth, that in many cases stuck out from the jaws.  These were truly fearsome predators and would have attacked and eaten any other animals in the sea.  Size estimates vary as most pliosaurs are only known from fragmentary and disarticulated remains but some of these creatures may have reached lengths in excess of 20 metres.

A Pliosaur Replica

CollectA Pliosaurus model.  A replica of a Pliosaurus marine reptile.

The picture (above) shows a scale model of a Pliosaurus, this is part of the CollectA Deluxe range of models and figures: CollectA Deluxe Prehistoric Life Models.

This new pliosaur, with the very strong bite, is a specimen found on the Norwegian archipelago of Svalbard, north of the Arctic circle.   The area is well known for marine reptile fossils, several plesiosaurs have been found and a number of pliosaurs and the Svalbard discovery may represent a new species.  Palaeontologists have been working with geological survey teams, in a bid to identify coal, oil and gas reserves, buried deep in the rocks, whilst studying the geology of the area a number of marine reptile fossils have been discovered.

To read an article about Norwegian marine reptiles: Is it a new species of Norwegian Marine Reptile or Not?

With only fragmentary fossils and partial skull material to work with; the research teams are having difficulty in establishing the taxonomy of many of their finds.  The Svalbard monster, affectionately nick-named “Predator X” by the scientists may be another specimen of a pliosaur fossil found on a different part of the island group.  Whatever it is, it would have been a formidable hunter, with an estimated length of 13 metres and a skull as long as a car.

Commenting on the bite force calculations, Joern Hurum, Associate Professor of Vertebrate Palaeontology at the Natural History Museum of Oslo stated:

“With a skull that’s more than 10 feet long you’d expect the bite to be powerful but this is off the scale.  It’s much more powerful than Tyrannosaurus rex”.

Pliosaur

Bite force analysis on extinct animals is calculated using mathematical formulae based on the strength and composition of the skull, the morphology of the teeth and the muscle attachments for the jaws.  Comparisons are made with extant animals to give a benchmark for bite forces, as the bite exerted by animals such as sharks, dogs, and humans can all be measured; (a bite force measuring device is called a gnathodynamometer).  Humans can generate a bite force in excess of 250 lbs per square inch across their molars, large dogs have a stronger bite, as do animals such as lions that can generate up to 1,000 lbs of force per square inch.

American Alligators have a bite force in excess of this, up to 3,000 lbs, whilst work with tyrannosaur skulls indicate a bite force of 15.000 lbs for T. rex.  Still according to the international team of scientists who worked on the pliosaur fossils, it seems that this brute could generate over twice as much bite force as a Tyrannosaurus rex.

Speaking about the bite force calculations, Greg Erickson (evolutionary biologist), stated that this was probably the biggest bite force ever calculated.  This pliosaur lived during the Late Jurassic and the fossils have been dated to around 147 million years ago (Tithonian faunal stage).  Some of the fossil teeth from this animal have been estimated to be over 30 cms long, making the teeth nearly twice as big as any known meat-eating dinosaur.

The scientists have reconstructed the marine reptile from a partial skull material and 20,000 fossilised fragments of skeleton and used the fossils of other pliosaurs as a template.

A Picture of a Pliosaur (Liopleurodon Model)

Picture credit: Everything Dinosaur

The pliosaur, estimated to have weighed 45 Tonnes, was similar to but had more massive bones than another fossil sea monster found on Svalbard in 2007, also estimated at over 50 feet long and the largest pliosaur specimen discovered to date.

Bite Force Measurements

Some scientists have developed the bite force measurements in extinct and extant animals and correlated them to brain size.  After all, as well as providing anchorage for the jaw muscles the skull is essentially a protective box housing the brain.  The scientists found that the larger the bite force the smaller the brain.  This pliosaur from the Norwegian territory of Svalbard, seems to back up this particular theory.  From examinations of the brain case it is thought that this particular marine reptile had a small brain, with much of the brain volume being made up of areas dedicated to sight and the sense of smell.  Very little of the brain was dedicated to problem solving (cerebrum).

When you have a bite capable of crushing metal, perhaps you don’t need to be that smart.

To view a model of a pliosaur (Liopleurodon), other marine reptiles and dinosaurs: Dinosaur and Marine Reptile Models and Figures.

Peking Man Fossils much Older than Previous Thought

Famous fossils of an early hominid (Homo erectus), commonly referred to as Peking Man may be much older than scientists think, according to new research using a refined fossil dating technique.

The research, which has just been published in the scientific journal “Nature”, dated fossils of these ancient hominids using a new radiometric technique involving the measuring of the decay of aluminium and beryllium in quartz associated with the fossils.

Radiometric Dating

Radiometric dating of fossils and rock strata is based on the amount of time it takes for certain radioactive substances to decay.  Atoms with identical chemical properties, but different atomic weights, are called isotopes.  Most elements are mixtures of different isotopes and radiometric dating measures the percentage decay of certain chemical isotopes over time within rocks and minerals.

Every isotope decays at a known rate and by measuring the amount of decay an age of the rock or fossil can be calculated.  This concept of radiometric dating based on the constant radioactive decay of isotopes was first studied in this country by physicists Ernest Rutherford and Arthur Holmes.  An American Bertram Boltwood was engaged in similar work in the USA.

Every radiometric date for a fossil calculated is dependent on the validity of certain assumptions, information tends to be provided allowing a range of dates to be proposed, + or – a few thousands or millions of years, depending on the object of study.  The revised date for the Peking Man fossils, is very different from the one using other isotope measures.  This new research, led by a team of Chinese scientists places the fossils over 280,000 years earlier, dating them to around 780,000 years ago (Pleistocene Epoch).

Hominid Evolution

Little is known about hominid evolution as the fossil record is so poor.  H. erectus is not thought to be the direct ancestor of our own species (H. sapiens), but from the fossil record of H. erectus it has been calculated that this human species persisted longer on the planet than any other species of hominid.  Fossil evidence indicates that the likes of Peking Man survived for approximately 2,000,000 years, eventually going extinct a mere 50,000 years ago.

The new data could effect our current understanding of the migrations of hominid species out of Africa and their spread throughout the Old World.  A lot of controversy has surrounded the discovery and excavation of H. erectus fossils.  When the first evidence of this ancient species of human was found in Java in the 19th Century, the fossils were used to provide support for Darwin’s assertion that mankind was descended from apes.  Many of the best hominid fossils from China were lost during the Second World War, but scientists such as palaeoanthropologists continue to study the existing fossils and look for new discoveries to help improve their understanding of human evolution.

Peking Man

This new research dates some Chinese H. erectus material recovered from  a famous set of caves in which over 40 individual early hominid skeletons were found.  The new dates will have an impact on the dates attributed to the spread of this human species out of Africa, through southern Europe and the Middle East and finally into Asia.  The research also indicates that Peking Man was able to survive in China during the much colder glacial periods that occurred during this part of the Pleistocene Epoch.  Previously, scientists had thought that Peking Man must have only migrated extensively during warmer interglacial periods, now this new data indicates that this adaptable species was able to cope with long periods of intense cold.

To read an earlier article on Peking Man: Signs of disease in fossils of early hominids.