All about dinosaurs, fossils and prehistoric animals by Everything Dinosaur team members.
/Palaeontological articles

Articles, features and information which have slightly more scientific content with an emphasis on palaeontology, such as updates on academic papers, published papers etc.

27 12, 2018

Convoluted Nasal Passages Helped Armoured Dinosaurs Cool Their Brains

By | December 27th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Armoured Dinosaurs Coped with the Mesozoic Heat Thanks to Nasal Air-conditioning

Being a very large dinosaur covered in armour, might help you to keep safe from attack by predatory dinosaurs, but this body plan does have its downsides.  For example, how do you keep cool when you have a very broad body?  New research from scientists based at Ohio University and the New York Institute of Technology College of Osteopathic Medicine at Arkansas State, suggests that those complicated Ankylosauria nasal passages acted like heat-exchanges helping to prevent these dinosaurs from overheating.  In essence, this study published in the academic, on-line journal PLOS One, suggests that members of the Ankylosauria clade had built-in air conditioning units in their noses.

Convoluted Nasal Passages Helped Armoured Dinosaurs to Avoid Overheating

Nasal air-conditioning in armoured dinosaurs.

Ankylosauria nasal passages used as heat exchanges.

Picture Credit: PLOS One with additional annotation from Everything Dinosaur

Panoplosaurus and Euoplocephalus Studied

The researchers, which included Jason Bourke (Assistant Professor at the New York Institute of Technology College of Osteopathic Medicine at Arkansas State), chose to examine the craniums of Euoplocephalus (E. tutus), a member of the Ankylosauridae family of dinosaurs along with the nodosaurid Panoplosaurus mirus.  A representative of the Nodosauridae family as well as a member of the Ankylosauridae was selected as Nodosaurs tend to have much narrower muzzles than the related Ankylosaurs.  In this way, the scientists were able to compare and contrast the different nasal passages associated with these two types of armoured dinosaur.

Assistant Professor Bourke commented:

“The huge bodies that we see in most dinosaurs must have gotten really hot in warm Mesozoic climates.  Brains don’t like that, so we wanted to see if there were ways to protect the brain from cooking.  It turns out the nose may be the key.”

Dr Victoria Arbour, an Authority on the Ankylosauria Poses Next to the Broad Skull of Euoplocephalus (E. tutus)

Dr Victoria Arbout next to a Euoplocephalus skull.

Victoria next to a skull of a Euoplocephalus tutus (University of Alberta).  Note the broad muzzle and the wide skull of this Late Cretaceous ankylosaurid.

Picture Credit: Angelica Torices

Computational Fluid Dynamic Analysis

The research team created three-dimensional, computer generated models of two famous skull fossils, a Panoplosaurus specimen housed in the Royal Ontario Museum collection and a Euoplocephalus skull from the American Museum of Natural History (New York).  A computational fluid dynamic analysis was then undertaken to map how air would have moved through the nasal passages as these dinosaurs breathed.  The scientists wanted to test the heat exchange capacity of the complex passages, to see how well the Ankylosauria noses transferred heat from the body to the inhaled air.

Co-author of the study, Lawrence Witmer (Ohio University), explained:

“A decade ago, my colleague Ryan Ridgely and I published the discovery that ankylosaurs had insanely long nasal passages coiled up in their snouts.  These convoluted airways looked like a kid’s ‘crazy-straw!’  It was completely unexpected and cried out for explanation.  I was thrilled when Jason took up the problem as part of his doctoral research in our lab.”

It is thought that these complex nasal passages gave members of the Ankylosauria clade, an exceptional sense of smell.  This may have been their primary function, however, noses are also heat exchangers, ensuring that air is warmed and humidified before it reaches the delicate lungs.  To accomplish this effective air conditioning, birds and mammals, including humans, rely on thin curls of bone and cartilage within their nasal cavities called turbinates, which increase the surface area, allowing for air to come into contact with more of the nasal walls.   Ankylosaurs and nodosaurids lacked turbinates, to compensate for this they evolved exceptionally long and twisty nasal passages.

Comparing Armoured Dinosaurs to Living Animals

When the researchers compared their findings to data from living animals, such as the nasal passages of an avian dinosaur (pigeon),  they discovered that the noses of armoured dinosaurs were just as efficient at warming and cooling respired air.  The length of the winding and twisting nasal passages in the two armoured dinosaurs studied were also measured.  In the narrow-snouted, nodosaurid Panoplosaurus, the nasal passages were a bit longer than the skull itself and in Euoplocephalus they were almost twice as long as the skull, which is why they are coiled up in the snout.

To see if nasal passage length was the reason for this efficiency in heat exchange, the researchers created alternative models with shorter, simpler nasal passages that ran directly from the nostril to the throat, as in most other animals.  The results clearly showed that nose length and the length of the nasal passages were indeed key to their air-conditioning ability.

Assistant Professor Bourke stated:

“When we stuck a short, simple nose in their snouts, heat-transfer rates dropped over fifty percent in both dinosaurs.  They were less efficient and didn’t work very well.”

Helping to Cool Brains

The blood vessels in the skull leading up to and surrounding the brain were mapped.  The scientists wanted to explore whether the internal plumbing of the snout helped to cool the brains of armoured dinosaurs.  The team found a rich blood supply running adjacent to the convoluted nasal passages.

Co-author Ruger Porter (Ohio University), explained:

“When we reconstructed the blood vessels, based on bony grooves and canals, we found a rich blood supply running right next to these convoluted nasal passages.  Hot blood from the body core would travel through these blood vessels and transfer their heat to the incoming air.  Simultaneously, evaporation of moisture in the long nasal passages cooled the venous blood destined for the brain.”

Euoplocephalus Kept a Cool Head

Cooling the brain of Euoplocephalus

Vascular pathways associated with the brain of Euoplocephalus tutus.  Red highlighted veins indicate main channels of heat transfer.

Picture Credit: PLOS One

Thermoregulation – A Problem for Large Animals

The large, broad bodies of Panoplosaurus and Euoplocephalus were really good at retaining heat, which might have some advantages, especially when you need to stay warm, but this does cause problems when large Tetrapods need to keep their cool.  This heat-shedding problem would have put them at risk of overheating even on cloudy days.  In the absence of some protective mechanism, the delicate neural tissue of the brain could be damaged by the hot blood from the body core.  In simple terms, the small brains of armoured dinosaurs might have been cooked inside the skull.

The complicated nasal airways of these dinosaurs were acting as radiators to cool down the brain with a constant flow of cooled venous blood.  This natural engineering feat also may have allowed some members of the Dinosauria to evolve into huge animals.

Lawrence Witmer added:

“When we look at the nasal cavity and airway in dinosaurs, we find that the most elaborate noses are found in the large dinosaur species, which suggests that the physiological stresses of large body size may have spurred some of these anatomical novelties to help regulate brain temperatures.”

26 12, 2018

“Little Foot” Reveals Her Secrets

By | December 26th, 2018|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Fourteen Years of Work to Tell the Story of “Little Foot”

Christmas is a time for family get togethers and spending time with relatives.  Today, we feature the astonishing story of the remarkable and nearly complete fossilised skeleton of an Australopithecine nicknamed “little foot” a member of the Hominidae family and as such, a long, distant relative of us all.  The Sterkfontein Caves in South Africa are located around twenty-five miles north-west of Johannesburg in Gauteng Province (South Africa).  Numerous fossils of hominids are known from the Caves and the surrounding area, which is called the Cradle of Humankind and Everything Dinosaur has reported on several recent and highly significant Australopithecine fossil finds, however, at an estimated 3.67 million years of age, “little foot” is the oldest Australopithecine specimen ever found in southern Africa.

The Partially Uncovered Remains of the Australopithecine Nicknamed “Little Foot”

In situ fossils of the Australopithecine "little foot" in the Sterkfontein Caves.

The fossilised remains of the Australopithecus nicknamed “little foot” found in the Sterkfontein Caves.  The skull can be seen in the bottom right corner of the photograph.

Picture Credit: PAST/Paul Myburgh

Lead researcher Professor Ron Clarke and his team have published the first, formal scientific description of the fossil material in the “Journal of Human Evolution”.  Such is the completeness of the skeleton, that anthropalaeontologists confidently predict that many more papers will be written, as this is the only known, virtually complete fossil skeleton of an Australopithecus discovered to date.  It has taken fourteen years of painstaking work to excavate the fossils and six years to clean and prepare them for detailed study.

Dedicated Research Leads to Scientific Breakthrough

In 1994 and 1997, Professor Clarke identified twelve foot and lower leg bones of one Australopithecus individual misidentified as animal fossils in boxes stored at Sterkfontein and at the University of Witwatersrand (Johannesburg).  Clarke and his assistants, Nkwane Molefe and Stephen Motsumi, then looked for and located the very spot where the bones had been blasted out by lime miners, probably sometime in the 1920’s deep inside the Sterkfontein Caves.  It was a real case of detective work, as Nkwane and Stephen worked in the caves to try to identify the very spot where the fossils that had been stored in the boxes, actually came from.  After one and a half of days of carefully searching the caves, they found that the pieces matched with two broken-through shin bones in a concrete-like cave infill and started the excavation process, first with hammer and chisel to remove the overburden, before turning to the painstaking process of locating and exposing the bones with an airscribe.

The Researchers were Able to Locate the Rest of the Skeleton by Matching Pieces Together

Identifying the rest of the "little foot" skeleton.

Researchers demonstrate how the rest of the skeleton was found by matching fragments of limb and ankle bones to fossil material exposed in the cave.

Picture Credit: PAST/Paul Myburgh

Unusual Taphonomy of the Female Australopithecine

The taphonomy of “little foot” is unusual.  The female (identified by the shape of the pelvis), fell into a cave and the body became mummified in the exceptionally dry conditions.  The absence of predators allowed the body to remain undisturbed but at some time in the past there was a slight displacement of some skeletal parts through slippage on the rock-strewn talus slope in the cave, crushing and breaking of some bones through rockfall and pressure, calcification after a change to wet conditions, and then slight downward collapse of part of the cave infill.  This partial collapse left voids that were later filled with stalagmitic flowstone that encased breaks through the femurs.  When the first attempts to date the fossils was made, an analysis of the stalagmite flowstone encasing the fossil was made.  However, the flowstones were later infills in voids created by the collapse that had broken and displaced parts of the skeleton.  The data gave a more recent date for the fossil, “little foot” was actually much older, having lived during the Zanclean stage of the Pliocene Epoch.

Professor Ron Clarke Demonstrates the Use of an Airscribe

Professor Ron Clarke demonstrates the use of an airscribe.

Professor Ron Clarke showing how an airscribe was used to remove the surrounding matrix.

Picture Credit: PAST/Paul Myburgh

Commenting on the earlier attempts to date the skeleton, Professor Clarke stated:

“The flowstones do not date the skeleton.  In 2015, cosmogenic isochron dates using 26Al and 10Be were published in Nature, showing that the age of the actual breccia containing the skeleton dates back ca 3.67 million years.  This is consistent with the original age estimates of around 3.5 million years that were proposed based on the low stratigraphic position of the deposit within the cave.”

Helping to Reassess the Australopithecus Genus

Study of the anatomical features of “little foot” suggests that the skeleton is most similar to the Australopithecine known as A. prometheus, which was proposed as a species in 1948 by the famous anthropologist Raymond Dart.  The phylogeny of the Australopithecines and related genera is controversial.  It is hoped that the virtually complete skeleton, so painstakingly excavated, will shed new light on taxonomic relationships, helping to fill in a number of evolutionary gaps.

Professor Ron Clarke and the Skull of “Little Foot”

The skull of "little foot" with Professor Ron Clarke

Professor Ron Clarke with the skull and left humerus of “little foot”.

Picture Credit: PAST/Paul Myburgh

Everything Dinosaur acknowledges the assistance of a press release from the University of Witwatersrand and supporting materials in the compilation of this article.

19 12, 2018

Dozens of Dinosaur Footprints Exposed at Hastings

By | December 19th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Geology, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Dinosaur Footprints Exposed by Cliff Erosion

The seaside town of Hastings in East Sussex is steeped in history.  It is synonymous with the battle that began the Norman conquest back in 1066 but scientists have been aware for many years that the cliffs to the east of the town contain evidence of much older inhabitants – dinosaurs.  Researchers from the Department of Earth Sciences at Cambridge University have published a paper this week documenting dozens of Early Cretaceous dinosaur tracks and footprints that represent at least seven different kinds of dinosaur.

Two Iguanodontian Prints from the Lee Ness Sandstone (Ashdown Formation) Exposed at Hastings

Two iguanodontian footprints from the Lee Ness Sandstone.

Examples of two iguanodontian footprints from the Lee Ness Sandstone (Ashdown Formation).

Picture Credit: Neil Davies/University of Cambridge

A Rich and Diverse Dinosaur Fauna

The footprints and trackways were identified and mapped by a team of researchers from Cambridge University between 2014 and 2018, following periods of extensive coastal erosion along the cliffs to the east of Hastings.  The footprints range in size from 2 cm wide to over 60 cm across.   These prints and tracks record a rich and diverse dinosaur fauna from the Lower Cretaceous – Lee Ness Sandstones (Ashdown Formation), which date from approximately 140 million years ago (Berriasian faunal stage of the Cretaceous).

The exact age of the Lee Ness Sandstone strata is unknown, however, the Ashdown Formation is estimated to be around 145-133 million years old, based on relative dating of ostracod fossils.

The researchers, writing in the academic journal ” Palaeogeography, Palaeoclimatology, Palaeoecology”, report on more than 85 exceptionally well-preserved dinosaur footprints, comprising prints from at least seven different types of dinosaur (ichnogenera).  They document the trace fossils eroding out of cliffs and their work records the greatest diversity of dinosaurs in a single location in Cretaceous-aged rocks found in the UK.  In particular, a variety of armoured dinosaurs (Thyreophora) are represented.

One of the Many Different Types of Armoured Dinosaur Print Found

Armoured dinosaur footprint - Ashdown Formation (Hastings).

A footprint ascribed to an armoured dinosaur (Thyreophora) from the Lee Ness Sandstone (Ashdown Formation).  The print has been assigned to the Tetrapodosaurus ichnogenus.

Picture Credit: Neil Davies/University of Cambridge

Details of Skin, Scales and Claws are Visible

The trace fossils are preserved in remarkable detail.  Impressions of skin, scales and even toe claw impressions have been preserved.

A Close View of an Iguanodontian Print Showing a Distinct Claw Impression

Preserved iguanodontian claw impression.

A close view of an iguanodontian claw impression preserved within one of the dinosaur footprints.

Picture Credit: Neil Davies/University of Cambridge

An Iguanodontian Footprint with Preserved Skin Impressions

Iguanodontian footprint showing skin impressions.

Some of the tracks from recent rock falls show skin impressions.  This is the skin impression from the underside of an iguanodontian footprint.

Picture Credit: Neil Davies/University of Cambridge

The best preserved prints come from large blocks of stone that are mapped and photographed after recently falling from the cliff.  The tracks are quickly eroded with prolonged exposure to the elements and from damage caused by further rock falls.  When dealing with a rapidly eroding cliff, it is essential that any fresh rock falls are examined and any fossils contained within the blocks are mapped and measured.

Two Photographs (February 2017 and February 2016) Showing the Extent of the Trace Fossil Erosion

Weathering of the dinosaur tracks at Hastings.

The effect of weathering on the trace fossils.  Over 12 months the tracks are heavily eroded.

Picture Credit: Neil Davies/University of Cambridge

Wealden Group Trace Fossils

The Ashdown Formation is part of the Wealden Group of rock formations, the most important sequence of dinosaur fossil bearing strata in England.  Numerous fossilised footprints are associated with the Wealden Group and the first report of tracks was made in 1846 by the Reverend Tagart, who described a series of three-toed prints, which he thought had been made by giant birds.  Never before has such a diverse footprint assemblage been mapped and documented in the British Isles.

A Table Showing the Different Types of Dinosaur Footprint (Morphotypes) Mapped at the Location

Lee Ness Sandstone dinosaur footprint analysis.

A table showing the number and characteristics of the Hastings dinosaur footprint fossils.

Table Credit: Palaeogeography, Palaeoclimatology, Palaeoecology with additional notation from Everything Dinosaur

One of the authors of the scientific paper, Anthony Shillito, a PhD student in Cambridge’s Department of Earth Sciences commented:

“Whole body fossils of dinosaurs are incredibly rare.  Usually you only get small pieces, which don’t tell you a lot about how that dinosaur may have lived.  A collection of footprints like this helps you fill in some of the gaps and infer things about which dinosaurs were living in the same place at the same time.”

Different Kinds of Theropod Dinosaurs

The footprints along with the various plant fossils and invertebrate trace fossils (burrows), are helping the scientists to put together a picture of life in this part of the world in the Early Cretaceous.  Dinosaurs dominated the biota, with several different types of meat-eating dinosaur (Theropods) identified, including a potential dromaeosaurid-like dinosaur, as two-toed prints (didactyl) have been found.

Different Types of Theropod Track Have Been Found

Different types of Theropod footprint. Scale bars = 5 cm.

Examples of different types of Theropod footprint (Lee Ness Sandstone – Ashdown Formation).

Picture Credit: Neil Davies/University of Cambridge

The picture above shows four different types of Theropod footprint identified at the Hastings site.  Picture (A) shows a large tridactyl (three-toed) cast with a long digit III and a faint heel impression.  The footprint in (B), is also large but the toes are narrower and elongated, maintaining a consistent width for their whole length.  The cast has no heel pad impression.  The Theropod morphotype (C), represents a much smaller animal with digit III being much longer than digits II and IV.  Intriguingly, the researchers have also logged potential two-toed prints (D), this suggests that this floodplain, braided environment might have been home to dromaeosaurid-like dinosaurs.

PhD student Shillito added,

“You can get some idea about which dinosaurs made them from the shape of the footprints, comparing them with what we know about dinosaur feet from other fossils lets you identify the important similarities.  When you also look at footprints from other locations you can start to piece together which species were the key players.”

Although, the majority of the footprints have been ascribed to Ornithopods, and several are referred to as iguanodontian, none of these prints were made by a member of the Iguanodon genus.  Iguanodon (I. bernissartensis), lived many millions of years after these prints were formed.  There have been many different types of iguanodont described, it is possible that the larger prints were made by an animal such as Barilium dawsoni.  The slightly smaller prints could have been created by the iguanodontid Hypselospinus (H. fittoni).

The Three-toed Tracks of a Small Ornithopod Dinosaur

Small Ornithopod trackway (Ashdown Formation).

Trackway assigned to a small, Ornithopod dinosaur.

Picture Credit: Neil Davies/University of Cambridge

Dinosaurs Helping to Shape the Environment

Anthony Shillito is focusing on the role played by dinosaurs in terms of shaping their environment, how dinosaurs behave as zoogeomorphic agents.  Large animals today, such as elephants and hippos can alter their habitats as they interact with their environment.  Hippos for example, can create river channels and divert the course of water flow.  Dinosaurs very probably did the same, with larger dinosaurs having a bigger impact than smaller dinosaurs.

The student commented:

“Given the sheer size of many dinosaurs, it’s highly likely that they affected rivers in a similar way, but it’s difficult to find a ‘smoking gun’, since most footprints would have just washed away.  However, we do see some smaller-scale evidence of their impact; in some of the deeper footprints you can see thickets of plants that were growing.  We also found evidence of footprints along the banks of river channels, so it’s possible that dinosaurs played a role in creating those channels.”

Evidence of Sauropods?

Footprint evidence indicating the largest dinosaurs of all, the presence of Sauropods is virtually absent from the site.  Three poorly preserved trace fossils have been tentatively ascribed to the Sauropoda, although they are very indistinct and could represent under traces representing the tracks of other ichnogenera.

It is very likely that there are many more dinosaur footprints hidden within the eroding sandstone cliffs of East Sussex, but the construction of sea defences in the area to slow or prevent the process of coastal erosion may mean that they remain locked away within the rocks.

The scientific paper: “Dinosaur-landscape Interactions at a Diverse Early Cretaceous Tracksite (Lee Ness Sandstone, Ashdown Formation, southern England)” by Anthony P. Shillito and Neil S. Davies published in Palaeogeography, Palaeoclimatology, Palaeoecology.

14 11, 2018

Fossil Bird from Late Cretaceous Utah – Deepens a Mystery

By | November 14th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Mirarce eatoni – Deepens the Mystery Over Late Cretaceous Avian Extinctions

All living birds from Albatrosses to Zebra finches belong to one group of avians – the Neornithes.  Our feathered friends share a number of key anatomical traits that defines them as a group from the smallest such as the Bee Hummingbird to the largest living bird, the Ostrich.  However, back in the Cretaceous, things were very different.  There were several different taxa of birds including the very diverse and highly successful Enantiornithines that shared the skies with early members of the Neornithines, but only the ancestors of today’s extant birds survived the end-Cretaceous extinction event and that’s a puzzle for palaeontologists.

The puzzle has just become a little more complex with the publication of a scientific paper in the on-line, open access journal “PeerJ”.  This paper describes the fossilised remains of an Enantiornithine that lived around 75 million years ago, in Utah (USA).  This prehistoric bird, about the size of a Raven, has been named Mirarce eatoni and its fossils show that it was probably a match for most modern birds in terms of its aerial abilities.

Perched on the Horns of a Utahceratops (Mirarce eatoni)

Mirarce eatoni - life reconstruction.

An illustration of the Late Cretaceous enantiornithine Mirarce eatoni.

Picture Credit: Brian Engh

This leads to one very intriguing question, if Enantiornithines like Mirarce were so advanced, then why after the Cretaceous-Palaeogene mass extinction event did only one group of birds survive?

A Complete Anatomical Description

The fossil material consists of several neck bones (cervical vertebrae), back bones (dorsal vertebrae), the fused caudal vertebrae making up the pygostyle, elements from the limbs, parts of the hips, a partial scapula, coracoid, the furcula (wishbone) and several other fragmentary elements including the radius and ulna.  This represents a veritable treasure trove of North American Enantiornithine fossils for palaeontologists to study, most North American members of this taxon are known from very scrappy fossil remains, mostly consisting of isolated fused leg bones and toes.  All in all, about 30% of the total skeleton is known and crucially, unlike most of the more complete Enantiornithine specimens from the Lower Cretaceous deposits of China, this specimen, is preserved in three-dimensions, it has not been crushed as flat as a pancake.  The excellent state of preservation and the number of fossil bones has permitted the researchers to undertake a complete anatomical description.

A Skeletal Reconstruction of the Newly Described North American Enantiornithine Mirarce eatoni

Mirarce eatoni skeletal reconstruction.

A skeletal reconstruction of the Enantiornithine Mirarce eatoni from Late Cretaceous Utah.  The bones shaded white represent known fossil material.  Note, cranial material is not known.

Picture Credit: Scott Hartman

The “Kaiparowits Avisaurid”

The specimen was originally discovered back in 1992, by University of California, Berkeley palaeontologist Howard Hutchinson, whilst he was exploring Kaiparowits Formation deposits for evidence of turtles.  It was quickly identified as an Enantiornithine and ascribed to the Avisauridae family, a family of prehistoric birds known from South America, North America, parts of Europe, Siberia and the Middle East (Lebanon).  The partial skeleton (UCMP 139500), was nicknamed the “Kaiparowits avisaurid”.   Although, its significance was noted, after all, the fossils represent the most complete example of an Enantiornithine ever found in North America, it remained undescribed.  All that changed when PhD student Jessie Atterholt (University of California, Berkeley), was given the opportunity to provide a formal scientific description.

Research Suggests that Mirarce eatoni was a Strong Flier and Well-Adapted to Life in the Late Cretaceous

Mirarce eatoni - life reconstruction.

A close-up view of the newly described Late Cretaceous bird Mirarce eatoni (colouration and plumage speculative).

Picture Credit: Brian Engh

A Strong and Capable Flier

In collaboration with her colleague Howard Hutchinson and with the support of Jingmai O’Connor, from the Chinese Academy of Sciences and an authority on Cretaceous fossil birds, a complete analysis of the fossil bones was undertaken.  This study revealed that M. eatoni possessed several of the same physical adaptations for highly refined powered flight that modern birds (Neornithines) have.

Fossils of Enantiornithines from the Lower Cretaceous of China, birds such as Confuciusornis sanctus show a mix of basal and more advanced anatomical traits.  For example, the breast bone (sternum), of C. sanctus, is relatively small.  Modern birds have a deeply keeled sternum, this allows the attachment of large muscles to aid powered flight.  The wishbone (furcula) of Confuciusornis and most other Early Cretaceous Enantiornithines, is little more than a curved bar.  However, the furcula of M. eatoni is shaped much more like the “V-shaped” wishbones of modern birds.  The furcula of Mirarce would have been able to flex and to store energy released during the flapping of the wings.

Commenting on the significance of these anatomical characteristics, Atterholt stated:

“We know that birds in the early Cretaceous, about 115 to 130 million years ago, were capable of flight but probably not as well adapted for it as modern birds.  What this new fossil shows is that Enantiornithines, though totally separate from modern birds, evolved some of the same adaptations for highly refined, advanced flight styles.”

The Furcula (Wishbone) of Mirarce eatoni

The furcula of Mirarce eatoni.

Two views of the wishbone (furcula) of Mirarce eatoni (A) dorsal and (B) ventral with line drawings.  Scale bar = 1 cm.

Picture Credit: PeerJ

Quill Knobs?

A close examination of the right ulna (lower arm bone), revealed evidence of two roughened patches preserved on the shaft of the bone.  These rough patches were interpreted as being attachment sites for quill knobs, that anchor the wing feathers to the skeleton and to help strengthen the wings for use in active, prolonged, powered flight.  Quill knobs are found in living birds.  This is the first time that such a feature has been seen in an Enantiornithine and indicates that Mirarce was, very probably, a strong flier.

Potential Quill Knobs Identified in an Enantiornithine (M. eatoni)

Quill knobs on an Enantiornithine.

Roughed structures on the ulna of Mirarce compared to the quill knobs found on the ulna of a Pelican.

Picture Credit: PeerJ

If these structures are quill knobs, then this suggests that this anatomical trait evolved in parallel with members of the Dinosauria (dromaeosaurids and other maniraptorans along with the ornithomimids) and in parallel with a number of types of prehistoric bird.

How Did Mirarce Get Its Name?

The genus name reflects that fantastic state of preservation of the fossil material (Latin “mirus” for wonderful) and after Arce, the winged messenger of the Titans in Greek mythology.  The trivial name honours Dr Jeffrey Eaton, in recognition of his work studying the vertebrates of the Kaiparowits Formation.  A spokesperson from Everything Dinosaur commented that this prehistoric bird’s name was pronounced “mere-ark-ee ee-tow-eye”.

But Why Did These Advanced Enantiornithines Die Out?

If Late Cretaceous Enantiornithines were just as advanced as modern birds, then, why did they die out with the non-avian dinosaurs while the ancestors of modern birds survived the extinction event?

Atterholt, who has moved onto a position of Assistant Professor and human anatomy instructor at the Western University of Health Sciences in Pomona (California), added:

“This particular bird is about 75 million years old, about 10 million years before the die-off.  One of the really interesting and mysterious things about Enantiornithines is that we find them throughout the Cretaceous, for roughly 100 million years of existence and they were very successful.  We find their fossils on every continent, all over the world, and their fossils are very, very common, in a lot of areas more common than the group that led to modern birds.  Yet modern birds survived the extinction while Enantiornithines go extinct.”

Forest Dwellers Versus Seed Eaters

A number of ideas have been put forward to help explain why some types of birds survived the end-Cretaceous mass extinction event whilst others did not.  For example, one hypothesis proposes that Enantiornithines were forest dwellers and when the asteroid strike/volcanism resulted in a dramatic loss of woodland habitats, these types of birds suffered more than other birds that lived in different environments.

The absence of cranial material prevents the researchers from investigating what Mirarce might have eaten.  Most known members of the Enantiornithes had teeth in their beaks and Mirarce supports the idea that these types of birds gradually got larger over time, but what this bird ate remains a mystery.  If it had been a predator of small vertebrates and insects, any major disruption to the food chain could have led to extinction.  However, a paper published in 2016 proposed that birds with toothless beaks such as the early Neornithines could have survived the extinction event by eating seeds that persisted in the soil.

To read more about this paper: Seed Eating May Have Helped the Birds Survive

The scientific paper: “The Most Complete Enantiornithine from North America and a Phylogenetic Analysis of the Avisauridae” by Jessie Atterholt, J. Howard Hutchinson and Jingmai K. O’Connor published in PeerJ.

13 11, 2018

Getting to the Bottom of Ornithischian Teeth

By | November 13th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Scientists Sink Their Teeth into Toothy Dinosaur Problem

Two of the most successful lineages of Ornithischian dinosaurs are the Ceratopsians (horned dinosaurs) and the Hadrosaurs (duck-billed dinosaurs).  These herbivores dominated the megafauna of many Late Cretaceous environments and one of the reasons for their success was their remarkable dental batteries.  Although horned dinosaurs and duck-bills processed plant food in their mouths differently, (they had different chewing and grinding actions), the rows of teeth permitted these types of plant-eaters to process the toughest vegetation extremely efficiently

The Dental Battery of a Typical Hadrosaurid

Typical Hadrosaur dental battery.

These teeth were made for grinding. The rows and rows of tough teeth in the jaw of a hadrosaurid – the dental battery.

Picture Credit: Dr Gregory Erickson

However, the evolution of these dental batteries is poorly understood, so a team of Canadian and Chinese scientists set out to examine how this dentition may have come about.  To do this they examined the teeth morphology and jaws of a little Ornithopod from north-eastern China called Changchunsaurus parvus.  This light-weight dinosaur that measured around 1.5 metres in length, is known from several skulls and other postcranial material from Jilin Province (China).

A Life Reconstruction of the Ornithopod Changchunsaurus (C. parvus)

Changchunsaurus Life Reconstruction

An illustration of the Chinese Ornithopod Changchunsaurus. Note scale bar = 1 metre.

Picture Credit: Everything Dinosaur

How Did “Typical” Ornithischian Dentition Develop?

Writing in the academic, on-line journal “PeerJ”, the researchers from Jilin University and the University of Alberta, describe how thin slices were taken from five jaw bones of this dinosaur so that teeth in the jaw could be studied.  In addition, the slices once polished to show their internal structure, would help the researchers determine tooth composition and to see how the teeth are maintained throughout the life of this little dinosaur.  Changchunsaurus makes a good candidate for this type of work, as it is known from numerous skulls (albeit, some of them are quite distorted), and it is regarded taxonomically as being close to origins of the Ornithopoda.

One of the Skulls of Changchunsaurus parvus Used in the Study

The holotype of Changchunsaurus parvus.

Image of the skull of the holotype specimen of C. parvus (JLUM L0304-j-Zn2).  The skull is shown in lateral view and the yellow shaded area indicates the area of the jaw from which the samples were taken.  Scale bar = 2 cm.

Picture Credit: Chen et al (PeerJ)

A Unique Method of Tooth Replacement

Among the notable features of Changchunsaurus parvus dentition is a unique method of tooth replacement that allowed this herbivore to recycle teeth without disrupting the continuous shearing surface formed by its tooth rows.  This permitted Changchunsaurus to have an efficient tooth-grinding surface all the time, thus helping it to process tough plant material.  The scientists also discovered that the teeth feature wavy enamel, a tissue type formerly thought to have evolved only in more derived members of the Ornithopoda.  The wavy enamel of Changchunsaurus is the phylogenetically earliest occurrence of this type of tissue known.

A Section of Dentary (Lower Jaw) Sample Along with Cross-sections of Teeth Showing Morphology

Changchunsaurus tooth morphology.

(B) a partial dentary showing the area cross-sectioned and magnified cross-sections of teeth (C to F) identifying teeth replacement and tooth morphology.

Picture Credit: Chen et al (PeerJ)

The picture above shows (B), an image of one of the partial lower jaws used in this research.  The purple line shows the plane of sectioning.  A whole view image of one of the thin sections through the lower jaw is shown (C) and (D) shows a magnified view of the process of tooth replacement.  Images (E) and (F) show highly magnified views of identified wavy enamel on the crown of replacement teeth (labial and lingual margins).

Commenting on the significance of this study, lead author Professor Chen Jun stated:

“These tissue-level details of the teeth of Changchunsaurus tell us that their teeth were well-adapted to their abrasive, plant-based diets.  Most surprisingly, the wavy enamel described here, presumably to make it more resistant to wear, was previously thought to be exclusive to their giant descendants, the duckbilled dinosaurs.”

This research contradicts previous interpretations that this type of wavy enamel arose in association with more complex hadrosauroid dentitions.  In view of its early appearance, the research team suggests that wavy enamel may have evolved in association with a shearing-type dentition in a roughly symmetrically-enamelled crown, although its precise function still remains somewhat of a mystery.

The authors suspect these features may have arisen early on in the Ornithopoda as they became adapted to herbivory, having to process tough vegetation.

The scientific paper:

“Tooth Development, Histology, and Enamel Microstructure in Changchunsaurus parvus: Implications for Dental Evolution in Ornithopod Dinosaurs” by Jun Chen , Aaron R. H. LeBlanc , Liyong Jin, Timothy Huang and Robert R. Reisz published in PeerJ.

5 11, 2018

Super Efficient Lungs Powered Dinosaur Success

By | November 5th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Bird-like Lungs Could Have Helped Dinosaurs to Dominate

There has been a great deal of debate regarding the rise of the Dinosauria.  How and when did these relatively unassuming members of the Dinosauria, which only made up a small proportion of terrestrial biota during the Middle Triassic, rise to dominance, out-competing a host of other reptilian groups?  The respiratory system of dinosaurs could provide a clue.  In a new study publised in the open access journal of the Royal Society (Royal Society Open Science), a team of researchers postulate that the lung-air sac system could have helped dinosaurs thrive in Earth’s oxygen-depleted atmosphere.

Did a Super-efficient Pumonary System Help the Dinosaurs to Thrive?

Dinosaurs probably had a super-efficient respiratory system.

New research suggests super-efficient dinosaur lungs assisted the rise of the Dinosauria.

Picture Credit: Chinese Academy of Sciences

Studying the Breathing Systems of Modern Birds and Alligators

Birds have a super-efficient respiratory system that is unique amongst the vertebrates.  However, palaeontologists remain uncertain as to when the avian-style lung evolved.  Did it evolve in dinosaurian ancestors or is it restricted to birds?  After all, if you are going to fly, then you need a very efficient and powerful set of lungs to get enough oxygen to your flight muscles.

This area of anatomy has attracted a great deal of debate.  Recently, Everything Dinosaur reported on a study conducted on a specimen of Archaeorhynchus spathula, a primitive bird (basal member of the Ornithuromorpha), from the Lower Cretaceous of China, that may show preservation of an advanced avian lung.  To read more about this research: Breathing Life into the Bird Lungs Debate

The scientists, including researchers from the University of Manchester, compared dinosaur lungs to those of living crocodilians and the lungs of extant birds.  Lead researcher, PhD student Robert Brocklehurst (School of Earth and Environmental Sciences, Manchester University), stated:

“The respiratory system of non-avian dinosaurs has been the topic of considerable study over the years, both in an attempt to shed light on the biology of now extinct members of the dinosaur family, and in order to understand the origins and evolution of modern birds and reptiles.”

Low Oxygen Levels in the Triassic and Early Jurassic

Today, our atmosphere contains approximately 21 percent oxygen, however, things have not always been like that.  During the Middle Triassic, through to the Early Jurassic, a time that saw the evolution and the radiation of the Dinosauria, the atmospheric oxygen percentage of our planet fell to around 15-17%.   With less oxygen in the air, a group of vertebrates with more efficient lungs would have had a definite evolutionary advantage over other terrestrial animals.

During the Triassic A Wide Variety of Terrestrial Reptilian Vertebrates Co-existed

The flora and fauna of the Late Triassic.

Dinosaurs, Aetosaurs, Phytosaurs and and Rauisuchians co-existed in the Triassic, but did super-efficient lungs help the Dinosauria to become dominant.

Picture Credit: Victor Leshyk

To investigate the different kinds of respiratory systems the team used Computerised Tomography (CT) scans to look at the lung cavities of four modern crocodilians and twenty-nine modern birds, including the largest living bird today, the ostrich and compared their structure with those of sixteen different dinosaur species.  The detailed scans revealed that all the dinosaurs had vertebrae more similar in shape to those of birds than those of crocodilians.  In addition, the scientists discovered that the dinosaur vertebrae jutted into the lung cavity, the same as found in living birds.

Robert explained:

“We thought some of the dinosaurs would have lungs more like birds, and others would be similar to reptiles, but this wasn’t the case at all.  Every dinosaur sample we scanned just looked like the birds we scanned.”

Dissection Used in this Study

As well as using CT scans, the team removed the lungs of an alligator and an ostrich, and found the skeletal support structures surrounding the lungs were very different in each animal.  The alligator’s lung cavity was smooth and allowed the lungs and other internal organs to glide as they move to pump air in and out while the animal swims.  However, the ostrich lung cavity was found to be furrowed, similar to the anatomical condition found in the dinosaurs.

The scientists concluded that having more efficient bird-like lungs permitted the dinosaurs to adapt and thrive in an oxygen depleted environment, whereas other groups including the the Crurotarsi clade of Archosaurs that gave rise to modern crocodiles, struggled.

Commenting on the research, co-author Professor Bill Sellers (Manchester University) added:

“If even the very first dinosaurs to evolve had bird-like lungs, this goes some way to explaining why dinosaurs became the dominant animal species of their time.  Other animal groups simply may not have had lungs as well suited to extracting oxygen from the air.  That simple evolutionary difference may have let dinosaurs rule world.”

The scientists concluded that respiratory and pulmonary modifications would have provided dinosaurs with more efficient means of oxygen uptake relative to other vertebrates during the environmentally hypoxic conditions which pervaded much of the early part of the Mesozoic.  This anatomical advantage enjoyed by the Dinosauria could thus potentially have contributed to their radiation and dominance over terrestrial ecosystems, which was to last for around 150 million years.

The Lungs of Dinosaurs Helped to Power Their Evolutionary Success

The sophisticated respiratory system of Ingentia prima.

The air sacs of Ingentia prima (green) the lungs shown in brown.  This large, Early Jurassic Sauropod had a super-efficient respiratory system.

Picture Credit: Jorge A. González

Everything Dinosaur acknowledges the assistance of a press release from Manchester University in the complilation of this article.

The scientific paper: “Vertebral Morphometrics and Lung Structure in Non-avian Dinosaurs” by Robert J. Brocklehurst, Emma R. Schachner and William I. Sellers published in Royal Society Open Science.

3 11, 2018

Elaborate Plumage in Confuciusornis

By | November 3rd, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Patterns on the Feathers of Confuciusornis as Complex as Modern Birds

A team of international scientists, including researchers from the China University of Geosciences (Beijing), the University of Ghent (Belgium) and the University of Texas at Austin (United States), have discovered that the patterns on the feathers of an Early Cretaceous bird may have been very similar to and as complex as the patterns seen on the feathers of extant Aves.  Writing in the academic, on-line journal “PeerJ”, the researchers conclude that the patterning of Confuciusornis feathers probably performed similar functions to the patterning on modern bird’s feathery coats, that is, they provided camouflage and also played a role in display.

Confuciusornis Integumentary Covering – Elaborate Plumage

Study suggests Confuciusornis had elaborate plumage.

Reconstruction of the plumage of Confuciusornis (specimen number CUGB P140).

Picture Credit: Li et al (PeerJ)

Complex Patterning Detected by Sophisticated Chemical Analysis

The specimen studied consists of a slab and counter slab of a single, individual bird from Early Cretaceous deposits in Fengning County, Hebei Province (north-central China).  The fossils are from the vertebrate collection of the China University of Geosciences and represent an example of Confuciusornis sanctus.  The research team identified exceptional feather preservation but poor preservation of the bones, the unusual state of preservation permitted the scientists to identify melanin signals in the fossilised feathers indicating a complex patterning of spots on the wings, throat and on the tuft of feathers at the back of the head forming a small crest.  The shape of the structures that form these patterns in conjunction with chemical analysis confirmed the diagnosis of the pigment melanin.  However, specific colouration associated with the patterns could not be discerned.

The Slab and Counter Slab or a C. sanctus Specimen Reveals Complex Patterning on the Plumage

Evidence of Confuciusornis plumage.

Evidence of plumage diversity in the Confuciusornithidae from the new specimen (CUGB P1401).

Picture Credit: Li et al (PeerJ)

The photograph (above) shows various views of the main slab of the fossil specimen showing details of the plumage.  The dots in (A) indicate places that were subjected to sampling, whereas B and C reveal the crest located on the back of the head.  Parts D and E show elements of the integumentary covering in close detail.

Using a range of analytical techniques including scanning electron microscopy and ion mass spectrometry (ToF-SIMS) the researchers concluded that the elaborate spotting on this specimen exceeds that found in exceptionally-preserved troodontids and compsognathids and rivals that in modern birds, suggesting that plumage patterns evolved greater complexity through avian evolution.

The exact age of the strata is uncertain, although it is believed that the deposits from Fengning County are approximately equivalent in age with the Dawangzhangzi Member of the Yixian Formation, around 122-123 million years old (Aptian faunal stage of the Early Cretaceous).  The data from this study suggests that Confuciusornis had more complex patterning than the patterning identified in Achiornis or in the stripes of the compsognathid Sinosauropteryx.  The research team conclude that this specimen of a primitive bird provides evidence to support the idea that complex patterning of feathers evolved at a relatively early stage in avian evolution.

The Link to Barn Owls

Integumentary patterns and colours play a variety of roles in living birds.  Such patterning in fossil specimens probably performed the same sort of functions and in addition, they can help to inform on the habitat in which the extinct creature lived.  In some modern bird groups, barn owls for example (Strigiformes), it has been observed that the size and placement of the spots on the feathers play a role in mate selection.  Male barn owls tend to prefer females with larger spots.  The patterning identified on this C. sanctus specimen leads to the intriguing idea that for confuciusornithids, just like barn owls, the location and the size of the spots on the plumage played a role in choosing a mate.

The scientific paper: “Elaborate Plumage Patterning in a Cretaceous Bird” by Quango Li, Julia A. Clarke, Ke-Qin Gao, Jennifer A. Peteya and Matthew D. Shawkey published in PeerJ.

27 10, 2018

Pachycephalosaurus – Was It Carnivorous?

By | October 27th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Theropod-like Front Teeth Identified in a Pachycephalosaur

Pachycephalosaurus, that dome-headed dinosaur that lived alongside such famous prehistoric animals as T. rex and Triceratops, in the Late Cretaceous of Montana, has always been a bit-player when it comes to depicting life in the very last couple of million years before the extinction of the non-avian dinosaurs.  Its more illustrious contemporaries tend to hog the limelight somewhat.  However, the scientific description of a nearly complete skull and jaws of what has been identified as a juvenile Pachycephalosaurus, might just have revealed a surprising side to this peaceful plant-eater.  The teeth in the front of jaws are triangular and pointed, reminiscent of the dentition of a meat-eating dinosaur.  Could palaeontologists have got Pachycephalosaurus wrong?

A Reconstruction of the Juvenile Pachycephalosaurus Skull and Jaws

Reconstruction of a Juvenile Pachycephalosaurus skull.

A reconstruction of the fossil skull of the juvenile Pachycephalosaurus that has Theropod-like teeth in the front of the jaws.

Picture Credit: Brian Boyle (Royal Ontario Museum)

Front Portion of the Jaws Suggests Omnivory in Certain Pachycephalosaurs

In a presentation made at the annual meeting of the Society of Vertebrate Palaeontology held in Albuquerque, New Mexico, Mark Goodwin (University of California Museum of Palaeontology) and David Evans (Royal Ontario Museum), described a near complete juvenile Pachycephalosaur skull from eastern Montana.  The back of the jaws contained the broad, leaf-shaped teeth which seem well suited to herbivory.  It had been assumed that the teeth in the front of the jaws (premaxilla and the anterior portion of the dentary, immediately behind the predentary), were the same shape.  However, until this fossil specimen was found, no record of the front teeth of these dinosaurs existed.  Palaeontologists may have to re-think their views on the diet of this member of the Hell Creek Formation biota.  The sharp, blade-like triangular teeth located at the front of the mouth seem adapted to ripping and tearing flesh.

The Teeth at the Front of the Jaws are Typical of a Meat-eating Theropod Dinosaur

Pachycephalosaurus Theropod-like teeth.

A close-up view of the teeth in the premaxilla (upper jaw) and the anterior portion of the dentary (lower jaw). Triangular Theropod-like teeth have been identified in a juvenile Pachycephalosaurus.

Picture Credit: Brian Boyle (Royal Ontario Museum) with additional annotation by Everything Dinosaur

Confusing Pachycephalosaurs

Pachycephalosaurus is the largest member of the Pachycephalosauridae family to have been scientifically described and notwithstanding a cameo appearance of a jail-breaking Stygimoloch in the recent “Jurassic World – Fallen Kingdom” movie, perhaps the most famous.  However, not a great deal is known about Pachycephalosaurus and other bone-headed dinosaurs.  Fossil remains tend to be very fragmentary and most species have been named from quite scrappy remains and then you have those amazing skulls to consider.

The CollectA Pachycephalosaurus Dinosaur Model

CollectA Pachycephalosaurus model.

A lithe Pachycephalosaurus dinosaur model.  Pachycephalosaurus (P. wyomingensis) is the largest known member of the Pachycephalosauridae with an estimated body length of 4.6 metres.

Picture Credit: Everything Dinosaur

Several species have been named based on the shape and cranial ornamentation associated with those thickened skulls.  The thick bone may resist erosion and provide palaeontologists with some fossil bone to study, but it has been suggested that the skulls of these dinosaurs changed dramatically as the animal grew.  So much so in fact, that a number of academics, including Mark Goodwin, have published scientific papers that cast doubt on the validity of many Pachycephalosaur species.  For example, palaeontologists such as Goodwin have put forward evidence to suggest that both Dracorex and Stygimoloch are not distinctive species, the fossils ascribed to these two genera could represent juvenile Pachycephalosaurus specimens.

It seems, just like many other types of Late Cretaceous Ornithischian dinosaur, the Pachycephalosaurs underwent extreme changes to the shape of their heads as they grew up.  Such changes in cranial morphology have resulted in the establishment of several species that may actually just represent examples of the same species but at different growth stages.

Some Palaeontologists Suggest that Radical Changes in Skull Shape and Ornamentation Do Not Indicate Different Species but Different Growth Stages

Different skull shapes and ornamentation linked to different growth stages.

It has been proposed that the cranial ornamentation and skull shape of Pachycephalosaurs changed as these animals grew and matured. This can cause confusion when trying to identify species.

Picture Credit: Kari Scannella with additional annotation by Everything Dinosaur

To complicate matters, Pachycephalosaur fossil material covers a period of approximately 2 million years.  Over this timescale, these animals evolved and their skull morphology changed, thus, further blurring the lines between different species and fossils of the same species but at different levels of maturation.

Confirming the Likely Diet of Pachycephalosaurus

It would be difficult to confirm that Pachycephalosaurus also ate other animals as well as plants, but not impossible.  Only one jaw fossil with the front teeth in situ has been found, so scientists don’t know whether the diets of these dinosaurs changed as they grew.  Perhaps, young Pachycephalosaurs were omnivorous, whilst when fully grown, adults tended to consume plants rather than other animals.  The rib cages of those genera which have a more complete fossil record, suggest that these bipeds had large guts, this would indicate a digestive system adapted to processing vegetation.  Professor Philip Currie (University of Alberta), who also attended the Society of Vertebrate Palaeontology meeting, has proposed that studying carbon isotopes preserved in the tooth enamel might provide further evidence relating to diet.  In addition, the many hundreds of examples of isolated, broken teeth from the Hell Creek Formation could be re-examined and checked for any potential affinities with the Pachycephalosauridae.  Feeding traces from fossil bone could also yield more data in support of the idea that bone-headed dinosaurs ate meat.

A Reconstruction of the Skull of an Adult Pachycephalosaurus

A replica skull of Pachycephalosaurus wyomingensis.

Pachycephalosaurus wyomingensis replica skull.

Picture Credit: Everything Dinosaur

A spokesperson from Everything Dinosaur commented:

“It is likely that there are many more examples of Pachycephalosaurs to be found in Upper Cretaceous rocks, hopefully, if more fossil material can be discovered, then palaeontologists will be able to piece together a more complete phylogeny of these strange dinosaurs.  Furthermore, if more examples of their dentition [teeth] come to light, then we might be able to gain a better understanding of their diets. “

21 10, 2018

Flea Bites and Dermal Infections in Glyptodonts

By | October 21st, 2018|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|2 Comments

Fleas on Glyptodonts

A new study examining one of the more bizarre types of megafauna from prehistoric South America has revealed that glyptodonts and their relatives suffered from fleas and dermal infections.  It seems that the hard, bony armour of some of these car-sized giants was no defence against flea bites.  Brazilian-based scientists writing in the open access, on-line journal “PLOS One”, have studied hundreds of pieces of glyptodont armour and discovered evidence of infections caused by fleas.

Such armour might have deterred a sabre-toothed cat from attacking, but the osteoderms and armoured tails were no defence against parasites.

A Skeleton of the Giant Glyptodont Panochthus spp.

Fossil glyptodont Panochthus.

A glyptodont fossil (Panochthus frenzelianus).  Researchers studied the tiles of bone (osteoderms) that formed the protective bony exoskeletons of extinct types of armadillo and determined that these armoured giants suffered from parasites and skin infections.

Picture Credit: R. Somma/Wikimedia Commons

Extinct Members of the Order Cingulata Studied

The scientists from Universidade Federal Rural do Semi-Árido, Mossoró (Brazil), studied the osteoderms that make up the exoskeleton of two extinct genera of glyptodonts Panochthus (pictured above) and Glyptotherium.  In addition, the research team examined the fossilised armour of another extinct armadillo-like creature Pachyarmatherium.  All these mammals belong to the Order Cingulata (armadillos and their relatives).  Damaged osteoderms were noted in all three genera and attributed to attacks by fleas and infections.  The scientists were able to identify the flea bites as coming from one particular genus  – Tunga.  The Tunga flea, sometimes referred to as the “jigger flea”, is native to South and Central America and is known to parasitise a number of large mammals including humans.  The bites cause well-defined circular lesions and perforations.  Such patterning was identified in a number of fossilised pieces of dermal armour.

Flea bites permitted secondary damage to be caused by the invasion of pathogenic microorganisms such as bacteria and fungi.

The External Surface of Osteoderms from the Glyptodont Glyptotherium Showing Pitting and Damage

Cingulata osteoderm parasite infection.

Osteoderms of the Brazilian glyptodont Glyptotherium showing damage from flea bites.

Picture Credit: PLOS One

The picture (above) shows severe pitting (black arrows) in (A) and three other osteoderms attributed to Glyptotherium which show stages of damage from (B), slight, through to (D) advanced pitting and the response to the damage by the deposition of more bone (calcium deposition).  The scale bar in A = 3 cm, whereas, the scale bar in B-D is 4 cm.

A Life Reconstruction of the Brazilian Glyptodont Glyptotherium

Glyptotherium life reconstruction.

A life reconstruction of the giant South American glyptodont Glyptotherium.

Picture Credit: Larjard/Wikimedia Commons

The bone alteration and re-growth identified in this study represent the first record of flea attack and pitting in two genera of large glyptodonts Panochthus and Glyptotherium and in a non-glyptodontid, large cingulate (Pachyarmatherium), from the Quaternary of the Brazilian Intertropical Region.  These newly identified flea bite occurrences and subsequent infections widen the geographic distribution of those diseases during the Cenozoic and provide more evidence for the co-evolution of parasites such as the Tunga flea and South American megafauna.

The scientific paper: “Ectoparasitism and Infections in the Exoskeleton of Large Fossil Cingulates” by Fábio Cunha Guimarães de Lima, Kleberson de Oliveira Porpino published in PLOS One

19 10, 2018

Feeding Traces on the Frill of a Young Centrosaurus

By | October 19th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Bite Marks Found on the Frill of a Young Centrosaurus

The movies and television documentaries featuring dinosaurs are stuffed full of them, but the fossil record tells a different story.  What are we referring to?  Dinosaurs hunting, attacking and fighting other dinosaurs.  Rarely has a programme or film been produced about the Dinosauria that does not feature some gory scenes of a bloody battle or a fearsome Theropod feasting on some poor, unfortunate plant-eating victim.  However, although such interactions obviously took place, the fossil record demonstrating such behaviour is extremely sparse.  A new paper, published in the open access journal “PeerJ”, reports on the discovery of bite marks preserved on the frill of a young Centrosaurus.

This raises two intriguing questions:

  • Which meat-eating dinosaur made the bite marks?
  • Is this evidence of predation or scavenging a carcass?

Dinosaurs Fighting – A Tyrannosaur Attacks a Horned Dinosaur (Styracosaurus)

Daspletosaurus fighting a horned dinosaur.

Tyrannosaur fighting a horned dinosaur.

Picture Credit: John Gurche

Bite Marks – Tell-Tale Signs of Predator/Prey Interaction

Bite marks on fossil bones can provide valuable information about interactions between carnivorous dinosaurs and the animals that they attacked.  It is not always possible to distinguish whether the trace fossils represent wounds inflicted on an animal during a fight, or whether these marks represent post-mortem feeding, such as consumption of the victim.  If there are signs of healing and bone growth, palaeontologists can be confident that the bite marks in that instance represent a lucky escape for the intended victim.  The key thing to note, is that the more data about bite marks that can be collected, the better the dataset that palaeontologists have to compare potential bite mark injuries against.

Part of the Skull of a Juvenile Centrosaurus With Tooth-marks

Ironically, quite a large proportion of the tooth-mark fossils associated with dinosaurs come from those deposits that are associated with the remains of large-bodied tyrannosaurids.  In this newly published paper, the scientists from Queen Mary University London and the Royal Tyrrell Museum (Alberta, Canada), report on the discovery of a portion of the skull from a juvenile horned dinosaur.  The bone, a fragment of the squamosal, which makes up part of the frill, was found on the surface of a dinosaur bonebed in the Dinosaur Provincial Park Formation.  The fossil is approximately 76.3 to 75.6 million years old and has been assigned to the horned dinosaur species Centrosaurus apertus.

Views of the Fragment of the Squamosal Bone (Centrosaurus apertus) and Line Drawings

Identifying potential bite marks in a bone from a juvenile Centosaurus.

The two sides of the partial squamosal bone from a juvenile Centrosaurus showing signs of damage/wear/bite marks. Actual fossil (A and B), interpretive line drawings (A1 and B1).

Picture Credit: PeerJ with additional annotation by Everything Dinosaur

Key

BM = Probable bite marks

? = Possible bite marks

Analysis of the fossil found numerous marks and gouges on both sides of the fossil bone.  Some of these marks could have resulted from damage due to transportation prior to burial.  Other marks could reflect effects caused by chemical erosion or the presence of vascular grooves.  However, the scientists were able to propose that at least some of the marks were due to teeth coming into contact with the bone.

The Position of the Partial Squamosal on the Skull of a Juvenile Centrosaurus and an Adult Skull Shown for Comparison

Juvenile (A) and adult (B) Centrosaurus skulls.

A comparison of Centrosaurus skulls (C. apertus) Juvenile (A) and adult (B).  The squamosal bone that makes up part of the frill is shaded grey, whilst the portion of bone in the study is shaded dark grey.

Picture Credit: PeerJ

Although it is difficult to assess the size of the horned dinosaur based on such a small fragment of bone, the scientists suggest that based on comparisons with squamosal bones from adults, the juvenile Centrosaurus was perhaps about a third the size of a fully grown Centrosaurus.

Which Dinosaur Made the Feeding Traces?

The researchers ruled out crocodiles, other reptiles and mammals when it came to identifying what creature made the bite marks.  This left the team with three types of Theropod dinosaur to investigate.  Troodontids, Dromaeosaurs and Tyrannosaurs are known from the Dinosaur Provincial Park Formation.  There is also the genus Richardoestesia to consider, its affinity within the Theropoda is uncertain.  The bite marks are too small to have been made by a large Tyrannosaur, but a juvenile Tyrannosaur might have scavenged the carcass.  It is also possible that a dromaeosaurid may have fed on the remains as well.  It is possible that both the dromaeosaurid and a young Tyrannosaur fed on the carcass, after all, modern carcasses may be fed on by multiple species (lions may kill a zebra but hyenas may chase them off the kill and rob them of the carcass – kleptoparasitism).

To read an article from Everything Dinosaur published in 2015 that looks at the structure of the teeth of different Theropod dinosaurs: Research to get your Teeth into

A Hypothesised Reconstruction of a Juvenile Gorgosaurus Feeding on the Carcass of a Juvenile Centrosaurus

A speculative illustration of a young Gorgosaurus feeding on the carcass of a juvenile Centrosaurus.

A young Tyrannosaur (Gorgosaurus) scavenging the carcass of the juvenile Centrosaurus.

Picture Credit: Marie-Hélène Trudel-Aubry/PeerJ

Slim Pickings

The marks on the squamosal fragment represent the first documented case of a carnivore consuming a juvenile ceratopsid, but the trace fossils may represent scavenging a corpse rather than predation.  However, there is not a lot of meat on a squamosal bone.  The scientists suggest that the feeding marks represent late stage consumption, as the most nutritious parts of the young Centrosaurus had already been eaten.  It is possible that a large Tyrannosaur made the kill, fed and then abandoned the carcase which was later picked over by other Theropods.

Despite the apparent preferences for feeding on juvenile dinosaurs, most feeding traces described to date are on the bones of adults which may have resisted being consumed and destroyed (even by large Tyrannosaurs).  Feeding traces on a juvenile dinosaur remain unusual and exceptionally rare.  Perhaps the size and shape of Ceratopsian skulls, even in juveniles, made them difficult to process or required an excess of handling effort for a relatively little reward in terms of food.

The scientific paper: “Bite Marks on the Frill of a Juvenile Centrosaurus from the Late Cretaceous Dinosaur Provincial Park Formation, Alberta, Canada” by David W.E. Hone, Darren H. Tanke and Caleb M. Brown published in PeerJ

Load More Posts