Study Finds Four Types of Feather-like Structures in Pterosaur Fossils

Most palaeontologists have accepted that it is likely that pterosaurs (flying reptiles), were covered in a sort of hairy fuzz, technically referred to as pycnofibres, that helped insulate their bodies and keep them warm.  However, an international team of scientists from Hong Kong University, Nanjing University (China), University College Cork, University College Dublin (Ireland), the Foundation for Scientific Advancement, (Arizona, USA), the Chinese Academy of Sciences and Bristol University (UK) have published a scientific paper that describes four kinds of feather-like structures associated with the fossilised remains pterosaurs.  If these structures are feathers, then this suggests that either the Pterosauria evolved feathers as a form of convergent evolution, or, that feathers evolved many millions of years earlier than previously thought – in a common ancestor of the Dinosauria and the Pterosauria.

A Life Reconstruction of the Chinese Anurognathid Pterosaur

Daohugou pterosaur life reconstruction.  Fossil evidence indicates that pterosaurs may have had at least four types of feathers.

Picture Credit: Yuan Zhang

Two Anurognathid Pterosaur Specimens Studied

Writing in the academic journal “Nature Ecology and Evolution”, the scientists report how high-resolution microscopy revealed evidence of different kinds of pycnofibres on two pterosaur fossils  (representing anurognathids), from the Daohugou Formation in Inner Mongolia.  Although, when the rocks that make up the Daohugou Formation were deposited has been debated and the relative dating of these sediments in relation to other Chinese Jurassic/Early Cretaceous formations has proved controversial, it is suggested that the pterosaurs, one of which represents a new species, lived approximately 160 million years ago.

Four feather-like structures were identified:

• simple filaments (hairs)
• bundles of filaments
• filaments with a tuft halfway down the shaft
• down feathers

The Scientists Identified Four Types of Feather-like Structures in the Fossils

Close-up views of different types of feather-like filaments identified in pterosaur fossils.

Picture Credit: Yang, Jiang, McNamara et al

An Amazing Discovery

One of the paper’s authors, Dr Maria McNamara (University College Cork), stated that some critics have suggested that there is only one simple hair-like type of pycnofibre, but this study shows different structures that we also see in dinosaurs, in essence real feathers.  Furthermore, the team identified melanosomes that indicate that some flying reptiles may have been coloured a sort of reddish brown.

Dr McNamara explained:

“We focused on areas where the feathers did not overlap and where we could see their structure more clearly.  They even show fine details of pigment granules, which may have given the fluffy feathers a ginger colour.  This discovery has amazing implications for our understanding of the origin of feathers, but also for a major time of revolution of life on land.  When feathers arose, about 250 million years ago, life was recovering from the devastating end-Permian mass extinction.”

The Enigmatic Anurognathidae

Only a handful of anurognathid fossils are known and only a few species have been assigned to this pterosaur family.  Although, the first anurognathids were described from Upper Jurassic deposits of Bavaria (Solnhofen limestone), the best preserved and most complete specimens came from the Daohugou Beds of Inner Mongolia.  Since these types of small, short-faced flying reptiles are known from Europe, South Korea, China and potentially North America, they seem to have been geographically widespread.  Although very rare, the Daohugou Bed fossil specimens have some soft tissue and muscle outline preservation and have provided palaeontologists with a lot of information on pterosaur anatomy.

An Anurognathid Pterosaur from the Daohugou Beds – Jeholopterus ninchengensis 

Pterosaur material from the Daohugou Beds.  This is a fossil specimen of the anurognathid pterosaur Jeholopterus ninchengensis.

Picture Credit: Chinese Academy of Sciences/Journal of Vertebrate Palaeontology

Re-writing the History of the Evolution of Feathers

Feathers are essentially highly modified scales; this new research could potentially re-write the evolutionary history of feathers.  One of the authors, Professor Mike Benton (Bristol University), explained:

“We ran some evolutionary analyses and they showed clearly that the pterosaur pycnofibres are feathers, just like those seen in modern birds and across various dinosaur groups.  Despite careful searching, we couldn’t find any anatomical evidence that the four pycnofibre types are in any way different from the feathers of birds and dinosaurs.  Therefore, because they are the same, they must share an evolutionary origin, and that was about 250 million years ago, long before the origin of birds.”

Birds have two types of advanced feathers used in flight and for body smoothing, the contour feathers with a hollow quill and barbs down both sides.  These types of feathers are found only in birds and the Theropod dinosaurs close to the evolutionary origins of the Aves (birds).  However, the other feather types of modern birds include monofilaments and down feathers, and these are seen much more widely across dinosaurs and pterosaurs.

The armoured dinosaurs and the giant Sauropods probably did not have feathers, but they were likely suppressed, meaning they were prevented from growing, at least in the adults, just as hair is suppressed in large-bodied animals today such as cetaceans, hippos and elephants.

High Resolution Microscopy Revealed Different Types of Feather-like Structures

Different types of integumentary filamentous structures identified in specimen number CAGS-Z070.

Picture Credit: Yang, Jiang, McNamara et al

Professor Benton added:

“This discovery has amazing implications for our understanding of the origin of feathers, but also for a major time of revolution of life on land.  When feathers arose, about 250 million years ago, life was recovering from the devasting end-Permian mass extinction.  Independent evidence shows that land vertebrates, including the ancestors of mammals and dinosaurs, had switched gait from sprawling to upright, had acquired different degrees of warm-bloodedness, and were generally living life at a faster pace.  The mammal ancestors by then had hair, so likely the pterosaurs, dinosaurs and relatives had also acquired feathers to help insulate them.  The hunt for feathers in fossils is heating up and finding their functions in such early forms is imperative.  It can rewrite our understanding of a major revolution in life on Earth during the Triassic, and also our understanding of the genomic regulation of feathers, scales, and hairs in the skin.”

Different Kinds of Pycnofibres – Different Functions?

Pterosaurs were the first back-boned animals to evolve powered flight.  However, following their extinction at the end of the Cretaceous, they left no living close relatives, nor indeed any near related analogues for scientists to study.  Whilst the presence of pycnofibres on the bodies of these flying reptiles is quite well accepted by the scientific community, their functions are not fully understood.  If different types of feather-like structures have been identified in two anurognathid pterosaur specimens, it is likely that other types of pterosaur had them too.

These different feather-like structures probably served a variety of functions, perhaps the first “pterosaur fuzz” evolved to provide insulation and then other types evolved perhaps to aid tactile sensing, visual communication and to assist with flight.

The scientific paper: “Pterosaur Integumentary Structures with Complex Feather-like Branching” by Z. Yang, B. Jiang, M. McNamara, S. Kearns, M. Pittman, T. Kaye, P. Orr, X. Xu and M. Benton and published in Nature Ecology and Evolution.

Everything Dinosaur acknowledges the assistance of a press release from Bristol University in the compilation of this article.

Crittendenceratops krzyzanowskii – A New Horned Dinosaur from Arizona

Many scientists and observers have described the last two decades as the “Golden Age” of dinosaur discoveries.  Since the turn of the century, there have been some astonishing fossil finds and many new species of dinosaur have been discovered and described.  None more so than with the horned dinosaurs and their relatives (Marginocephalia).  Over the last few years, we have reported on numerous new types of Ceratopsian, many of these new horned dinosaurs having been discovered in strata laid down in the United States, for example, Medusaceratops, Aquilops, Kosmoceratops and Utahceratops.  Surprisingly, there had been no new horned dinosaurs named in 2018, that is no longer the case with a scientific paper published describing a new Centrosaurine dinosaur from the Late Cretaceous of Arizona – Crittendenceratops krzyzanowskii.

A Life Reconstruction of the Newly Described Ceratopsian Crittendenceratops krzyzanowskii

A life reconstruction of the newly described Ceratopsian Crittendenceratops (2018).

Picture Credit: Sergey Krasovskiy

Only a Few Dinosaurs Named from Arizona

Writing in the New Mexico Museum of Natural History and Science Bulletin, the researchers, Sebastian G. Dalman and Asher Lichtig, both Research Associates at the New Mexico Museum of Natural History and Science, in collaboration with John-Paul Hodnett from the Maryland-National Capital Parks Commission and Spencer G. Lucas (a curator at the New Mexico Museum of Natural History and Science), describe Crittendenceratops and assign it the Centrosaurinae subfamily of horned dinosaurs and specifically to the Nasutoceratopsini tribe.

There have been so many new horned dinosaurs from North America named and described in the last twenty years or so, that this has led to a revision of Ceratopsian taxonomy.  For example, the Nasutoceratopsini was erected recently (2016).

To read an article that summarises this revision: Redefining the Horned Dinosaurs

Despite the wealth of dinosaur fossil material associated with the western United States, Crittendenceratops is one of only a handful of dinosaurs named from Arizona.

A Reconstruction of the Parietosquamosal Frill of C. krzyzanowskii

A line drawing showing a reconstruction of the parietosquamosal frill of Crittendenceratops krzyzanowskii.

Picture Credit: New Mexico Museum of Natural History and Science

From the Fort Crittenden Formation

This new herbivore has been described from fragmentary fossil material, including skull elements from the shale member of the Fort Crittenden Formation.  Two individual animals are represented by the fossils.  Crittendenceratops is estimated to have been around 3.5 metres in length and would have weighed about 750 kilograms.  It lived 73 million years ago (Campanian stage of the Cretaceous) and the rocks that yielded the bones were deposited along the margins of a large lake that was present in an area southeast of Tucson, Arizona.

The Nearly Complete Left Squamosal (Skull Bone) of Crittendenceratops

Left squamosal bone of Crittendenceratops (NMMNH P-34906) dorsal view.

Picture Credit: New Mexico Museum of Natural History and Science

Honouring Stan Krzyzanowski

The new species was named by Sebastian G. Dalman, John-Paul Hodnett, Asher Lichtig and Spencer G. Lucas.  The genus name reflects the rock formation where the fossils were found (Fort Crittenden Formation), whereas the trivial name honours the late Stan Krzyzanowski, a Research Associate from the New Mexico Museum of Natural History and Science, who discovered the first bones to be ascribed to this new dinosaur in the Adobe Canyon area eighteen years ago.  Crittendenceratops can be distinguished from other members of the Centrosaurinae subfamily by the unique shape of the bones in its frill.

The scientific paper: “A New Ceratopsid Dinosaur (Centrosaurinae Nasutoceratopsini) from the Fort Crittenden Formation Upper Cretaceous (Campanian) of Arizona” by Spencer G. Lucas, Sebastian Dalman, Asher Lichtig and John-Paul Michael Hodnett published in the New Mexico Museum of Natural History and Science Bulletin.

Everything Dinosaur acknowledges the assistance of a press release from the New Mexico Museum of Natural History and Science in the compilation of this article.

Weewarrasaurus pobeni – Hints at Different Kinds of Dinosaur Communities

The fortuitous discovery of pieces from the lower jaw of a small, plant-eating dinosaur is helping scientists to discover more about the Cretaceous dinosaurs that once roamed Australia.  Writing in the academic journal “PeerJ”, the researchers provide evidence to support the idea that there were numerous small-bodied Ornithopods at high latitudes in south-eastern Australia, whilst further north, in what would have been slightly warmer environments, these types of dinosaurs co-existed with much bigger Ornithopods and Titanosaurs.

The dinosaur has been named Weewarrasaurus pobeni (pronounced wee-whah-rar-sore-us poe-ben-eye) and it is the first new dinosaur to be described from New South Wales for nearly 100 years.

A Life Reconstruction of the Newly Described Gondwanan Ornithopod Weewarrasaurus pobeni

A life reconstruction of the small Ornithopod Weewarrasaurus.

Picture Credit: James Kuether

A Lucky Fossil Find

Adelaide-based opal buyer Mike Poben spotted the fossil pieces in a bucket of opal rubble from the Wee Warra opal field at Lightning Ridge (New South Wales, Australia).  The dinosaur was named in honour of the location and the trivial name recognises the contribution of Mr Poben who donated the specimens for research.

Numerous opalised dinosaur fossils are known from the Lightning Ridge area.  The material, including fragments of bones and isolated teeth come from the Griman Creek Formation.  Recent radiometric dating indicates that these deposits are around 100 to 96 million years old (Cenomanian stage of the Late Cretaceous), making these rocks some 10 million years younger than equivalent exposures containing dinosaur fossils found in northern Queensland.

The Fossil Jaw Fragments (Right Dentary) of Weewarrasaurus pobeni

The right dentary of W. pobeni (medial view). The two pieces are part of the same lower jaw.

Picture Credit: PeerJ

Unfortunately, the underground mining process involves breaking up the rocks, so any specimens found tend to consist of isolated broken pieces, however the presence of a scalloped-shaped tooth in the object immediately caught the attention of Mr Poben, so he was able to quickly appreciate that this was part of a jawbone.  Lightning Ridge is the only place in the world where dinosaur bones and teeth routinely turn to opal.  Corresponding author of the scientific paper, Dr Philip Bell (University of New England), explained that researchers were now looking into acquiring more fossil material from opal mines.

Dr Bell stated:

“Unfortunately, the fossil remnants we see are almost always part of mining spoil… but on another hand, we would never get to see even those fragments if it wasn’t for mining.”

Opal Helps to Identify a Dinosaur

One of the benefits of the presence of opal in the fossil is that the distinctive banding pattern formed helped the scientists to identify that the two fossil pieces belonged to the same jawbone.

Views of the Jawbone Fossil (Weewarrasaurus pobeni)

Weewarrasaurus pobeni fossils (right dentary fragments in medial view).

Picture Credit: PeerJ/Dr Bell (University of New England)

The picture above shows three views of the fossils, (A), medial; (B), dorsal; and (C) lateral views.   The dashed black line shows the outline of the missing pieces that would have comprised a more substantial part of the dentary.  The dashed red lines indicate the distinctive banding pattern in the opal used to estimate the extent of the missing area.  Another jawbone fragment (LRF 766), representing a right dentary with teeth in situ from the nearby Three Mile opal field has also been assigned to this new dinosaur species.

Faunal Differences in Different Regions of Prehistoric Australia

The Griman Creek Formation fossils from Lightning Ridge indicate that there were numerous small Ornithopods living in this environment during the Cenomanian stage of the Late Cretaceous.  This research provides further evidence to support previous studies that favour a general abundance of small-bodied basal Ornithopods in high-latitude localities of south-eastern Australia.  These little dinosaurs, most of which were under two metres in length, inhabited a verdant flood plain, but this part of the Gondwana was at approximately 60 degrees south.  Today, Australia is much further north, the city of Sydney (New South Wales), is located at approximately 33.86 degrees south.  During the Cretaceous, the dinosaurs that inhabited the part of Australia we now call New South Wales, would have had to endure periods of darkness in the year when the sun dipped below the horizon, although the presence of ectothermic reptiles such as crocodyliforms and turtles indicate that average minimum temperatures may not have fallen below 5 degrees Celsius.  Even so, the climate may have been too extreme for Sauropods.  Cretaceous deposits in Queensland (Winton Formation), have revealed several Titanosaurs, but the colder temperatures experienced further south may have limited Sauropod distribution.

The researchers conclude that although future dinosaur fossil discoveries have the potential to alter these interpretations, it is suggested that the Griman Creek Formation at Lightning Ridge occupied a “meeting point” between more northern Sauropod-dominated faunas and the Ornithopod-dominated faunas that existed further south.

Computer Generated Images from Fossil Scans Helped to Identify Ornithopod Characteristics

Three-dimensional renders of the posterior dentary fragment.

Picture Credit: PeerJ

To read a recent article about an opalised dinosaur toe bone found in South Australia: Lost Dinosaur Toe Bone Turns Up on the Internet

Toe Bone Turns Up on the Internet

A rare dinosaur bone, one of only three dinosaur fossils known from the state of South Australia, is going on display at the South Australian Museum some forty-five years after it was lost to science.  The opalised bone, representing a single toe bone (phalanx), is believed to come from a type of Theropod dinosaur and although named Kakuru kujani, which was officially described from opalised remains representing lower leg bones back in 1980, very little is known about this Cretaceous dinosaur.

The toe bone was found in Andamooka in the far north of South Australia sometime in the early 1970’s.  It was spotted for sale in an opal shop in Hindley Street, Adelaide by Neville Pledge, the South Australian Museum’s then curator of fossils, in 1973.  Neville had the foresight to take several photographs, measurements and plaster casts of the toe bone.  However, shortly afterwards, the item was sold and it disappeared from the scientific community.

The Opalised Toe Bone on Display at the South Australian Museum

The five cm long opalised dinosaur toe bone from South Australia.

Picture Credit: Ashleigh Glynn

The Tale of a Toe Bone

In April 2018, the bone was spotted up for sale on the internet by Coober Pedy resident Joy Kloester, who purchased the bone and then offered it to the South Australian Museum.  The Museum’s Senior Collections Manager for Earth Sciences, Ben McHenry acted quickly to acquire the specimen for the vertebrate palaeontology department.

Mr McHenry commented:

“I couldn’t believe our luck in finding the same bone after forty-five years.”

Dinosaur bones from South Australia are extremely rare.  The only two other bones known to science found to date are also part of the vertebrate fossil collection of the South Australian Museum.  During the Early Cretaceous period (around 110 million years ago, Albian fauna stage), when dinosaurs roamed the land, most of South Australia was under water, being part of the ancient Eromanga Sea.  The sediments deposited on the floor of this ancient sea now form the rocks of the Great Artesian Basin and preserve the abundant remains of marine life that can be viewed in the Museum’s Opal Fossil gallery.  This special dinosaur toe bone will be on display in this gallery from today (December 3rd).  Neville Pledge is now an Honorary Researcher at the South Australia Museum, it seems his discovery from 45 years ago, has now joined him at this highly respected institution.

What Sort of Dinosaur was Kakuru kujani?

Kakuru kujani (pronounced: Kah-koo-roo koo-yan-eee), is believed to be about the size of a turkey.  Unfortunately, given the limited fossil material, it is not possible to identify its taxonomic position with the Theropoda.  K. kujani was described from fragmentary lower leg bones (tibia and possible fibula fragments), the toe bone may not belong to this genus at all, but given the lack of other candidates, the Museum has assigned the bone to Kakuru.  It has been postulated that this dinosaur was an oviraptorid, although some affinity to the Abelisauridae has also been proposed.  Its formal classification remains Theropoda incertae sedis, which means it has an uncertain placement within this Sub-order.

A Speculative Reconstruction of Kakuru kujani

A speculative reconstruction of the Theropod dinosaur Kakuru kujani from South Australia.  In this illustration, K. kujani is depicted as an oviraptorosaurian dinosaur.

Picture Credit: South Australian Museum

Everything Dinosaur acknowledges the assistance of a press release from the South Australian Museum in the compilation of this article.