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

16 07, 2018

Does the Fossil Record Represent True Diversity?

By | July 16th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

How Helpful is the Fossil Record When it Comes to Extinct Animal Diversity?

When it comes to understanding biodiversity in ancient palaeoenvironments, scientists have to rely on the fossil record for their information. Ghost lineages can be inferred, the likelihood of related genera can be proposed using cladistics and phylogeny, but ultimately it is the fossils that form the basis of our understanding about how diverse life was in the past.  This reliance on fossil material has numerous drawbacks.  The fossil record is very incomplete and there is a large preservation bias between different organisms and different environments.  For example, a snail with its hard shell, living on the muddy bottom of a shallow sea has got more chance of becoming a fossil than a soft-bodied mushroom living in a temperate forest.

Palaeontologists have to ask themselves: can the fossil record can be trusted to provide information about biodiversity?

Tyrannosaurus rex Might Be Popular with Museum Visitors but Other Meat-eating Dinosaurs Have a Much Less Complete Fossil Record

T. rex skeleton at the Frankfurt Natural History Museum

T. rex might be very popular with museum visitors, but in reality most of the Tyrannosauroidae are very poorly known.

Mosasaurs Help to Provide Some Insight

Species are often named and described on the flimsiest of evidence, take for example famous dinosaurs such as Trachodon and Troodon, dinosaurs that were first named based on the finding of isolated teeth.  Fortunately, these days ,there is a higher bar set when it comes to establishing that a fossil represents an animal new to science, although some new species are still named based on very fragmentary fossils.

Could it be that our understanding of past biodiversity is simply related to the quality of fossil material in different geological rock formations through time?  This question relates to a fundamental debate within palaeontology about the quality and trustworthiness of the fossil record.

Researchers from Bristol University and Leeds University set out to explore the relationship between the number and quality of fossils and their relationship with past diversity.  Writing in the journal “Palaeontology”, the scientists focused on the Mosasauridae, that family of marine reptiles closely related to today’s snakes and lizards that thrived in the Late Cretaceous before meeting their demise at the same time as the dinosaurs.

Using Mosasaur Fossils to Examine the Diversity of Extinct Animals

A Mosasaur exhibit on display.

Apex predator of the Late Cretaceous – looking at Mosasaur fossils to understand the diversity of extinct groups of animals

Picture Credit: Bonhams

Mosasaurs evolved into a number of different forms during the Cretaceous, some were giants, measuring more than thirteen metres in length and were the apex predators of marine ecosystems.  Other species were much smaller such as the five-metre-long Platecarpus that fed on fish, squid and ammonites.  Scientists have even identified a possible freshwater species of Mosasaur (Pannoniasaurus inexpectatus).

The Fossil Record Indicates Diversity Amongst the Mosasauridae

Illustrating the diversity of the Mosasaurs.

Fossils illustrate the diversity of the Mosasauridae.

Picture Credit: Tom Stubbs and Dan Driscoll

The picture (above), illustrates some of the diversity found in the Mosasauridae.  Some species are known from very fragmentary remains such as isolated bones and teeth, other species have been named based on far more complete skeletons.  The partial lower jaw (top picture), shows the rounded teeth, almost ball-like teeth of a member of the Globidensini tribe of Mosasaurs.   A group of Mosasaurs that evolved specialised teeth to cope with hard-shelled prey such as ammonites and crustaceans (durophagous diet).  The photograph (far right), shows a single Mosasaur tooth.  It is very large and the crown is robust and pointed, typical dentition associated with predatory behaviour, attacking and consuming other large vertebrates.  The picture (bottom), shows a complete, restored skull of a Mosasaur with a jaw containing small, recurved teeth indicative of a diet of fish or other small slippery creatures such as squid.

Dr Dan Driscoll (Bristol University), the lead author of the research stated:

“Mosasaurs have one of the richest vertebrate fossil records and have attracted study for over two centuries.  The first Mosasaur described was in 1808!  Often, studies of fossil record quality have focused simply on the numbers of fossil species, however, it is important to consider the completeness of individual fossil specimens, and whether this distorts our view of diversity.  To do this, robust statistical analysis is required.”

Using Mathematical Models to Test the Completeness of the Mosasaur Fossil Record

The researchers documented over four thousand and eighty Mosasaur specimens and scored them for their degree of completeness.  This is the largest quantitative analysis of its kind undertaken to date.  By using mathematical modelling, the scientists were able to demonstrate that fossil completeness does not bias the fossil record of Mosasaurs and that the rich fossil record of the Mosasauridae does provide an accurate illustration of the diversity and evolutionary history of these marine reptiles.

The Diverse Mosasauridae Family Occupied a Number of Niches within Marine Ecosystems

Tylosaurus attacks.

Fearsome marine reptiles such as Tylosaurus were apex predators.

Picture Credit: BBC Worldwide

Bristol University’s Dr Tom Stubbs, a co-author of the study explained:

“Mosasaurs were key players in Late Cretaceous marine ecosystems.  Our study confirms that Mosasaurs were a successful group of animals that continued to diversify through their evolutionary history, before being abruptly wiped out by the extinction event that also impacted dinosaurs and many other groups.”

The conclusions provided by this new research reveals new insights into the evolution of the Mosasauridae, and highlights that, although the fossil record is most definitely incomplete, variable fossil completeness does not appear to bias large scale evolutionary and ecological patterns.

Co-author, Dr Alex Dunhill, (School of Earth and Environment at the University of Leeds), added:

“Palaeontologists often presume that the vertebrate fossil record is heavily biased by sampling.  This may be so but, here we show that variation in the completeness of fossil specimens does not appear to bias large scale evolutionary patterns.”

The scientific paper: “The Mosasaur Fossil Record Through the Lens of Fossil Completeness” by D. Driscoll, A. Dunhill, T. Stubbs and M. Benton published in Palaeontology.

12 07, 2018

In the Pink! Life’s First Colour

By | July 12th, 2018|Geology, Main Page, Palaeontological articles|0 Comments

Scientists Identify the World’s Oldest Biological Colours

A team of international scientists including researchers from the University of Liège, Florida State University and the Australian National University, in collaboration with a colleague based in Japan have discovered the oldest colours preserved in the fossil record.  An analysis of the remains of microscopic, 1.1 billion-year-old cyanobacteria suggest that life back in the Proterozoic was “in the pink”.  Pink coloured pigments have been extracted from ancient marine shales that form part of the Taoudeni Basin of Mauritania (north-western Africa).

When Held Up in the Light the Pink Colouration can be Seen

A vial of pink pigments porphyrins - representing the oldest intact pigments in the world.

The oldest colours found to date.

Picture Credit: Australian National University

One of the authors of the scientific paper, published in the “Proceedings of the National Academy of Sciences of the USA”, Dr Nur Gueneli (Australian National University), explained that the pigments taken from the marine black shales were more than six hundred million years older than previous pigment discoveries.

Dr Gueneli commented:

“The bright pink pigments are the molecular fossils of chlorophyll that were produced by ancient photosynthetic organisms inhabiting an ancient ocean that has long since vanished.”

Samples of the shales laid down during the Stenian, the last geological period of the Mesoproterozoic Era, were ground into fine powder before the ancient molecules of long extinct cyanobacteria could be extracted and analysed.  The fossils reveal a range of colours from a blood red to a deep purple in their concentrated form, but when diluted, it is the colour pink that dominates.

Dr Gueneli, who undertook this research whilst studying for a PhD added:

“The precise analysis of the ancient pigments confirmed that tiny cyanobacteria dominated the base of the food chain in the oceans a billion years ago, which helps to explain why animals did not exist at the time.”

Lack of Things for Higher Organisms to Eat

Complicated animal life was not able to evolve, according to one hypothesis, as it was restrained by the lack of food in the ocean.  In essence, life on Earth could not pick up the evolutionary pace as food webs were constrained by the amount of primary producers in the ecosystem.  Through the team’s discovery of molecular fossils of the photopigment chlorophyll in 1.1-billion-year-old marine sedimentary rocks, they were able to quantify the abundance of different organisms that uses the sun’s energy to produce food (phototrophs).  Nitrogen isotopic values of the fossil pigments revealed that the Pan-African Ocean was dominated by cyanobacteria, while larger planktonic algae were very scarce.  These findings support the hypothesis that small cells at the base of the food chain limited the flow of energy to higher trophic levels, potentially retarding the emergence of large and complex life.

Associate Professor Jochen Brooks, of the Research School of Earth Sciences (Australian National University), one of the authors of the scientific paper, stated that the emergence of more complex life forms was likely to have been restricted by the limited supply of larger food particles, such as algae.

Associate Professor Brooks explained:

“Algae, although still microscopic, are a thousand times larger in volume than cyanobacteria, and are a much richer food source.  The cyanobacterial oceans started to vanish about 650 million years ago, when algae began to rapidly spread to provide the burst of energy needed for the evolution of complex ecosystems, where large animals, including humans, could thrive on Earth.”

9 07, 2018

Triassic Dinosaurs Just Got a Lot Bigger!

By | July 9th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Ingentia prima – Giant Late Triassic Sauropodomorph from Argentina

Argentina might have been home to huge, plant-eating dinosaurs associated with Cretaceous-aged strata, after all, one of the biggest terrestrial vertebrates known to science is the Titanosaur called Argentinosaurus (A. huinculensis), just one of a number of super-sized leviathans from this part of the world.  However, a team of scientists, writing in the academic journal “Nature Ecology & Evolution” have announced the discovery of yet another giant, South American dinosaur, but this time one that roamed northern Argentina around 210 million years ago, in the Late Triassic.

The dinosaur, classified as a member of the Sauropodomorpha, has been named Ingentia prima and it was certainly very big for a Late Triassic animal, with an estimated body weight of around ten tonnes and a length of approximately ten metres.  To provide a comparison, the Sauropodomorph Plateosaurus (P. engelhardti), from the Late Triassic of western Europe, that would have been a contemporary of Ingentia prima, is estimated to have reached a length of about eight metres with a body mass of around four tonnes.  The later Sauropodomorph Lufengosaurus (L. huenei), from the Early Jurassic of China, might have been around six metres long and is estimated to have weighed more than 1.5 tonnes, Ingentia is much, much bigger.

Sauropodomorpha Size Comparison

Sauropodamorpha size comparison.

Sauropodomorpha size comparison Plateosaurus, Lufengosaurus and Ingentia prima compared.

Picture Credit: Everything Dinosaur with I. prima illustration by Jorge A. González

First Giant

The discovery of Ingentia prima does rather upset the dinosaurian apple cart.  It had been thought that gigantism in the Sauropodomorphs evolved in the Early Jurassic, however, here was a ten-tonne giant, comparable in size to those Early Jurassic Sauropods that roamed some thirty-five million years later.  The evolution of giant, plant-eating, long-necked dinosaurs came about as a result of the development of numerous anatomical characteristics but I. prima displays many features of the body plan of basal, small Sauropodomorphs and lacks most of the anatomical traits previously regarded as adaptations to gigantism.

The Fossilised Material in the Field (Partial Exposure)

Ingentia prima fossils.

The fossil material representing a single, large individual dinosaur is partially exposed.

Picture Credit: Cecilia Apaldetti

Lead author of the scientific paper, Dr Cecilia Apaldetti (Universidad Nacional de San Juan, San Juan, Argentina), commented:

“It [Ingentia] was enormous.  It was at least twice as large as the other herbivores of the time and until now it was believed the first giants to inhabit the Earth originated in the Jurassic, about 180  million years ago.”

The dinosaur’s scientific name pays tribute to its size, the name translates from the Latin to “first giant”.  It had been thought, that if the first dinosaurs appeared around 230 million years ago, it took fifty million years for the first giants to evolve, the discovery of a partial skeleton in San Juan Province (north-western Argentina), has changed all that.

Quebrada del Barro Formation

The fossil material consisting of shoulder blades, cervical vertebrae (neck bones) and elements from the forelimbs, heralds from the Quebrada del Barro Formation.  The Ingentia fossil material was found adjacent to the fossilised remains of three individuals belonging to the already known and closely related species Lessemsaurus sauropoides, which had been named and scientifically described back in 1999.

The researchers, in addition to describing I. prima formally for the first time, were able to examine the three new specimens of Lessemsaurus sauropoides.  Ingentia has been placed in a newly erected family of long-necked dinosaurs, the Lessemsauridae, a branch of the Sauropoda that evolved gigantic forms like the later Eusauropods (true Sauropods).  The Eusauropoda includes those famous Jurassic giants such as Diplodocus, Brontosaurus and Brachiosaurus, as well as the later Titanosaurs such as the mighty Argentinosaurus, which roamed Argentina some 115 million years after Ingentia became extinct.

Circular Saws were used to Help Extract the Large Fossil Bones

Extracting the fossils of Ingentia prima.

Circular saws were used to remove the larger blocks of fossils after they had been jacketed.

Picture Credit: Cecilia Apaldetti

Why so Big?

Early Sauropodomorphs were small, agile bipeds, but the ancestors of Ingentia adopted a different evolutionary strategy.

A spokesperson from Everything Dinosaur commented:

“Developing a larger gut would allow more effective processing of tough vegetation, enabling these types of dinosaurs to extract more nutrients from the plants that they consumed.  Furthermore, by becoming big, these dinosaurs would have had less to fear from the predators that shared their environment, including Theropod dinosaurs.  If you are very large, a meat-eating dinosaur might avoid you and look for an easier meal elsewhere.  Becoming a giant is an evolutionary strategy found in a number of herbivorous animals”.

The Remarkable Skeleton of Ingentia prima

The lessemsaurids (Ingentia, Lessemsaurus and a third Early Jurassic dinosaur from South Africa named Antetonitrus), may have lacked the extremely long necks found in later Eusauropods, but their bones reveal some remarkable adaptations nonetheless.  Pneumatic structures have been identified in the vertebrae (air sacs), this indicates that these dinosaurs had a sophisticated and extremely efficient bird-like respiratory system.  These air sacs will have also helped to prevent these animals from overheating, a problem with large creatures, (surface area to volume ratio – hence one of the reasons why African elephants have large ears).  This kind of respiratory system implies the presence of cavities in their bones – a pneumatised skeleton that would have helped to lighten the animal and make locomotion more efficient.

Although Ingentia shows these adaptations to gigantism, it lacks many of the features associated with the later Sauropods.  For example, its legs were more bent and not the huge, weight-bearing columns associated with the Diplodocidae and the Macronaria.

The Remarkable Bones and Respiratory System of Ingentia prima

The sophisticated respiratory system of Ingentia prima.

The air sacs of Ingentia (green) the lungs shown in brown.

Picture Credit: Jorge A. González

A Dinosaur Ahead of Its Time

The quality of bone preservation permitted the research team to examine the histology of the dinosaur’s bones.  The scientists compared the bone growth in the new fossils with those of an earlier, bipedal Sauropodomorph as well as a later Eusauropod.  The histology of the earlier Sauropodomorph revealed a cyclical growth pattern, the animal growing in spurts, whereas, the Eusauropod bones, when examined in cross-section, revealed another pattern of growth.  This dinosaur grew acyclically, growing throughout its long life.  Members of the newly erected Lessemsauridae family grew differently.  Their bones show evidence of growth spurts, a trait found in their ancestors but when they grew, they really put on a spurt.  The researchers identified a growth rate of around two to three times faster than the already impressive rate of the later Eusauropods.

Ingentia demonstrates that the first wave of colossal giant dinosaurs evolved some thirty-five million years earlier than previously thought.  In addition, with an accelerated growth rate, unique limb adaptations and a bird-like respiratory system, the Lessemsauridae got big but they did it in a different way when compared to the later long-necked dinosaurs.

When it comes to the “LESSemsauridae” – Less may actually mean more…

The scientific paper: “An Early Trend Towards Gigantism in Triassic Sauropodomorph Dinosaurs” by Cecilia Apaldetti, Ricardo N. Martínez, Ignacio A. Cerda, Diego Pol & Oscar Alcober published in the journal Nature Ecology & Evolution.

2 07, 2018

A Placoderm “Platypus” Fish from Australia (Where Else)?

By | July 2nd, 2018|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Brindabellaspis – Placoderm Resident on Australia’s First Reef

The Queensland coast (Australia), might be famous for its Great Barrier reef today, but this was not Australia’s original reef, some 400 million years ago, there was a reef, located in what is now New South Wales, mostly built by entirely different types of organisms, that was a natural wonder of the Early Devonian.  Living on the bottom of the shallow sea in which this ancient reef formed was a strange-looking fish, with a sensitive beak, oddly reminiscent of another, not quite so ancient resident of  “Down Under” – a duck-billed platypus.

New Research Suggests that Brindabellaspis stensioi had a Sensitive “Beak” Like A Duck-billed Platypus

Brindabellaspis life reconstruction.

Brindabellaspis stensioi illustration.

Picture Credit: Jason art Shenzhen

The Placoderm, named Brindabellaspis stensioi was originally scientifically described in 1980.  However, new fossil specimens, revealed by carefully removing the rock matrix using dilute acids, have shed new light on the evolution of jaws and provided palaeontologists with evidence that the earliest fish dominated ecosystems supported a myriad of forms.

Limestone beds exposed on the shores of Lake Burrinjuck in New South Wales have preserved an extensive reef fauna.  Over seventy species of fish have been identified to date, of these, it is the Placoderms that dominate, with around 45 species named and described so far.  Palaeontologists from Flinders University (South Australia) and the Australian National University (Australian Capital Territory), have reconstructed two of the ancient fossils and discovered that Brindabellaspis had a long bill (rostrum), extending out in front of its eyes.

The Picturesque Limestone Beds of Lake Burrinjuck

400 million-year-old limestone beds of Lake Burrinjuck.

Lake Burrinjuck in New South Wales (Australia).

Picture Credit: Flinders University

One of the authors of the study, published in “Royal Society Open Science” Benedict King, a Flinders University graduate stated:

“This was one strange looking fish.  The eyes were on top of the head and the nostrils came out of the eye sockets.  There is this long snout at the front, and the jaws were positioned very far forward.”

Unique Sensory System

Following a comprehensive evaluation of the skull including the anterior portion (revealed for the first time with these new specimens), the researchers discovered an exceptionally long premedian bone forming an elongated rostrum, supported by a thin extension of the postethmo-occipital unit of the braincase.  This seems to be a modified form of pressure sensor, perhaps used to detect prey in the muddy/sandy bottom of the seafloor.

Professor John Young (Flinders University), a world authority on ancient fish and a co-author of the paper added:

“We suspect that this animal was a bottom-dweller.  We imagine it used the bill to search for prey, somewhat like a platypus, while the eyes on top of the head looked out for danger from above.”

Adding the Missing Pieces – Thirty-Eight Years Later

For Dr Gavin Young (Flinders University), the discovery of the front portions of the skull and that remarkable, sensitive rostrum helps to “flesh out” his original research on Brindabellaspis stensioi.  Dr Young has spent more than five decades studying the fossil fish from the Lake Burrinjuck limestone beds, Dr Young was responsible for naming and describing this Placoderm in 1980, now thanks to these new fossils and high-resolution X-ray tomography, this 400 million-year-old fish has a face, albeit a very peculiar one, but one that may demonstrate convergent evolution with the egg-laying monotreme (platypus – Ornithorhynchus anatinus).

New Specimens of  Brindabellaspis stensioi  Included in this Study

Brindabellaspis fossils and a line drawing.

The rostrum and one of the new skull fossils with a line drawing.  Note scale bar (left) equals 1 centimetre.

Picture Credit: Royal Society Open Science

Dr Young explained:

“When we saw the dense sensory tubes on another broken snout, we immediately thought of the local platypus.  I am very gratified there is finally an accurate reconstruction of this strange skull.”

Specialists and Not Generalists

The scientists conclude that as Brindabellaspis was clearly such a specialist, then the ancient reef was a thriving and very diverse ecosystem with very probably, a range of specialist organisms making a living on the reef and in the surrounding shallow waters.

Professor Long commented:

“Despite this being one of the earliest well-known ecosystems including many species of fish, the inhabitants of this ancient reef were clearly not in any way primitive.  The new findings show that they were highly adapted and specialised in their own right.”

The Elongated Premedian Plate (Rostrum) of Brindabellaspis stensioi

Brindabellaspis elongated premedian plate.

The elongate premedian plate of Brindabellaspis. ANU V3247 in dorsal (a) and ventral (b) views. (c,d).  Interpretative drawings of a and b.  Scale bars represent 10 mm.

Picture Credit: Royal Society Open Science

The scientific paper: “New Information on Brindabellaspis stensioi Young, 1980, Highlights Morphological Disparity in Early Devonian Placoderms” by Benedict King, Gavin C. Young and John A. Long published in by Royal Society Open Science.

Everything Dinosaur acknowledges the assistance of a press release from Flinders University in the preparation of this article.

26 06, 2018

Watching the Birdie – Head for the Southern Hemisphere

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

Fossil Bird Challenges Perceptions About Avian Evolution

Researchers from the Swedish Museum of Natural History and the Milner Centre for Evolution at the University of Bath, have re-examined the fossilised remains of an ancient bird from Wyoming, which casts doubt on the generally held perception that the ancestor of all modern birds originated in the southern hemisphere.  The fossil bird, named Foro panarium, was originally described and named back in 1992, but where this 52 million-year-old bird would perch on the avian family tree has been the subject of much debate.

Dr Daniel Field (Milner Centre for Evolution), in collaboration with Alison Hsiang (Swedish Museum of Natural History), have produced a scientific paper that supports the idea that this robust but poor flyer with relatively long legs from the famous Eocene-aged Green River Formation, is the earliest known example of a group of birds called Turacos or “banana eaters”.

Comparing the Skeleton of F. panarium to the Extant Ross’s Turaco (M. rossae)

Holotype of Foro panarium compared to living Turaco species.

The holotype specimen of F. panarium compared to a living species of Turaco.

Picture Credit: BMC Evolutionary Biology

The picture (above) shows a stylised image of the holotype specimen of Foro panarium (a, c, d, e) compared to (b) 3-dimensional CT rendering of the pectoral region of Ross’s Turaco (Musophaga rossae).  Note scale bar is 10 centimetres.

Birds – the Most Specious of all the Terrestrial Vertebrates

Some commentators might state that we are living in “the age of mammals”, it is true that many of  the apex predators, large herbivores and hyper-carnivores around today are mammalian, but in terms of the number of species, there are more species of birds (estimated at 11,000), than there are species of mammals, or amphibians and reptiles for that matter.  In addition, there are far more bird species in the southern hemisphere than in the northern hemisphere.  Charles Darwin during his voyage on the Beagle, marvelled at the great diversity of bird species he encountered on his travels through South America, the Galapagos and islands of the Pacific Ocean.  Naturalists are very aware of the dramatically uneven global distribution of today’s Aves.  Not only are species numbers higher south of the Equator, but many major groups of birds are entirely restricted to Africa, Australasia and South America which were all, once upon a time, part of the great southern super-continent of Gondwana.

Turaco Birds are Known for their Beautiful Plumage

 Guinea Turaco (T. persa).

A beautiful Turaco bird.  A Guinea Turaco (T. persa)

Picture Credit: Dr Daniel Field

Dr Field and Dr Hsiang set out to examine the avian fossil record to see if they could help to explain the uneven geographic distribution of modern-day birds.  Did, as many scientists believe, the ancestor of all modern birds (Neornithes), originate in the southern hemisphere, or are there more complex issues in play restricting the distribution of birds through deep time?

Turning to the Fossil Record for Answers

In order to map the evolutionary history of our feathered friends – the avian dinosaurs, the scientists turned to the fossil record for answers.  Writing in the academic journal “BMC Evolutionary Biology”, the scientists report their study of the 52-million-year-old fossil bird named Foro panarium.  The taxonomic placement of this species has been controversial, as the fossil shows a mixture of anatomical characteristics.  However, using updated information relating to other Eocene and Palaeocene bird species, the researchers concluded that the specimen represents the earliest known relative of the “banana eaters”, the Turacos (Musophagidae family).  Turacos today are entirely restricted to sub-Saharan Africa.  This enigmatic family of birds are renowned for their bright, gaudy plumage, elaborate head crests and some species have very loud alarm calls (hence their nick-name in parts of Africa, “go away birds”).  The feathers of several species contain unique pigments that generate bright green and magenta tones.

If the American fossil bird F. panarium is indeed a basal member of the Musophagidae, then it suggests that these birds had a much wider, global distribution in the distant past.  If this is the case, then why are extant Musophagidae  members restricted to Africa?

Biogeographical  and Bayesian Statistical Phylogenetic Analysis

Furthermore, an examination of the fossil record of Aves, suggests that Foro panarium is not the only example of a fossil bird being discovered outside the modern geographical distribution for that kind of bird.  For example, the Trogoniformes (Trogons and Quetzal birds), which are restricted to the southern hemisphere today, have basal members preserved in fossils from the Messel Shales of Germany.

The Beautifully Preserved Remains of a Bird from the Messel Shales of Germany

Bird Fossil - Messel shale.

A bird fossil from the Messel shale of southern Germany.

Picture Credit: Everything Dinosaur

The scientists confirm the complex historical biogeography of crown birds across geological timescales.  The geographical distribution of ancient species and their subsequent radiation and restriction is likely to be much more complicated than previously thought.  The idea that the common ancestor of all living birds (Neornithes), arose in the southern hemisphere is not discounted, but this paper suggests that this assertion may not be as strongly supported by the evidence as previously thought.

Commenting on the significance of this study, Dr Field stated:

“Our picture of bird evolutionary history will continue to grow sharper as each new bird fossil gets unearthed.”

Shedding Light on the Turaco Lineage

It is likely that the birds went through a rapid phase of evolution after the End-Cretaceous extinction event that saw the demise of many ancient avian groups as well as the non-avian dinosaurs.  A seed-eating diet, may have helped numerous lineages to persist as the world’s ecosystems recovered.

To read a recent article about this: Seed Eating May Have Helped Some Types of Bird to Survive the Cretaceous Extinction Event

For the F. panarium fossil specimen itself, it may provide vital clues as to the age of the Musophagidae.  Turacos must have diverged from their closest living relatives by at least 52 million years ago, (by the middle of the Ypresian faunal stage), thus supporting the idea of a rapid diversification of the Aves during the Palaeocene Epoch.  The fossil also provides some intriguing insights into the evolution of modern Turaco biology.  Living Turacos have short hindlimbs and hind feet claw adaptations to help them to perch in trees.  In contrast, the fossilised hindlimbs of Foro panarium are quite long, suggesting that this bird was more of a ground-dweller than its modern descendants.

The scientific paper: “A North American Stem Turaco, and the Complex Biogeographical History of Modern Birds” by Daniel J, Field and Allison Y. Hsiang published in the journal BMC Evolutionary Biology

23 06, 2018

Stem Mammal Skull Re-shapes Ancient Landmasses

By | June 23rd, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Cifelliodon wahkarmoosuch – Pangaea Split Later Than Thought

A fossilised skull of a stem mammal dating back to the Lower Cretaceous suggests that the super-continent Pangaea split up more recently than previously thought.  The skull, identified as a new species, comes from Utah and it indicates that there were still land links between North America and other landmasses making up Pangaea, as this is the first evidence of a member of the Hahnodontidae to have been described from North American fossil material.

Linking Super-continents Cifelliodon wahkarmoosuch

Cifelliodon wahkarmoosuch life reconstruction.

A life reconstruction of the stem mammal C. wahkarmoosuch.  The fossilised skull of this small stem mammal suggests that Pangaea broke up later than previously thought.

Picture Credit: Jorge A. Gonzalez

Scientists, including researchers from the University of Chicago and the Utah Geological Survey writing in the journal “Nature”, have named the new stem mammal Cifelliodon wahkarmoosuch.

Lead author of the study Zhe-Xi Luo (University of Chicago), explained that palaeontologists had thought that the primitive precursors to today’s mammals – the monotremes, marsupials and placental mammals, were anatomically similar and ecological generalists.  However, recent fossil discoveries suggest that many stem mammals were very specialised.

Zhe-Xi Luo stated:

“Now we know mammal precursors developed capacities to climb trees, to glide, to burrow into the ground for subterranean life, and to swim.  With this new study, we also know that they dispersed across from Asia and Europe, into North America, and farther onto major southern continents.”

Honouring Richard Cifelli

The genus name honours American palaeontologist Richard Cifelli, at Oklahoma University.  Professor Cifelli is regarded as one of America’s leading experts in North American Cretaceous mammals.  The species name “wahkarmoosuch”, means “Yellow Cat” in the local native American language for that part of Utah.  The fossil comes from the Yellow Cat Member of the Cedar Mountain Formation.  Sophisticated high-resolution computerised tomography (CT), was used to create a detailed, three-dimensional model of the skull.

James Kirkland, co-author of the paper and a Utah State palaeontologist commented:

“The skull of Cifelliodon is an extremely rare find in a vast fossil-bearing region of the Western Interior, where the more than 150 species of mammals and reptile-like mammal precursors are represented mostly by isolated teeth and jaws.”

The Fossilised Skull of C. wahkarmoosuch and a Computer -generated Image of the Fossil Material

The skull and scan of C. Dorsal view of the fossil skull (left) and the computer generated image (right) C. wahkarmoosuch.

Dorsal view of the fossil skull (left) and the computer-generated image (right) of  C. wahkarmoosuch.

Picture Credit: Huttenlocker et al

Nocturnal Predator

Cifelliodon wahkarmoosuch was small, weighing around two kilograms, it was probably about the size of a terrier.  This might be tiny compared to some extant North American mammals around today such as the moose, wolf and bison, but back in the Early Cretaceous, some 130 million years ago, it was a relative giant amongst its Cretaceous contemporaries.  Analysis of the teeth and preserved teeth sockets suggest that it had teeth were similar to fruit-eating bats and it could bite, shear and crush.  It may have been omnivorous, eating small animals but also incorporating plants into its diet.

The skull reveals that this newly described species had a relatively small brain and giant olfactory bulbs to process smell.  The small orbits (eye-sockets), suggest that C. wahkarmoosuch probably relied on its sense of smell to find food.  It probably did not have good eyesight or colour vision and Cifelliodon may have been nocturnal.

Super-Continent and Land Bridges

The research team have assigned Cifelliodon to the clade Haramiyida, a group of mammaliaform cynodonts that have a long temporal range in the fossil record.  Most of these animals are known from fragments of jawbone or fossil teeth.  The teeth, which are by far the most common fossil remains of these animals, resemble those of another ancient type of mammal the Multituberculata (Multituberculates).  With the discovery of a North American Haramiyidan, scientists are going to have to re-examine fossil teeth from this area that had previously been assigned to the Multituberculata, these teeth might represent members of the Haramiyida.

The fossil discovery emphasises that Haramiyidans and some other vertebrate groups existed globally during the Jurassic-Cretaceous transition, meaning the corridors for migration via landmasses forming the super-continent Pangaea remained intact into the Early Cretaceous.  There must have been land bridges permitting the migration of these small animals for longer than previously thought.

Most of the Jurassic and Cretaceous fossils of Haramiyidans are from the Triassic and Jurassic of Europe, Greenland and Asia.  Hahnodontidae was previously known only from the Cretaceous of northern Africa.  The Utah fossil discovery provides evidence of migration routes between the continents that are now separated in northern and southern hemispheres.

Commenting on the implications for the break-up of Pangaea, Adam Huttenlocker (University of Southern California), a co-author of the study said:

“But it’s not just this group of Haramiyidans.  The connection we discovered mirrors others recognised as recently as this year based on similar Cretaceous dinosaur fossils found in Africa and Europe.”

The researchers conclude that hahnodontid mammaliaforms had a much wider, possibly Pangaean distribution during the Jurassic–Cretaceous transition.

Everything Dinosaur acknowledges the help of a press release from the University of Chicago in the compilation of this article.

The scientific paper: “Late-surviving Stem Mammal Links the Lowermost Cretaceous of North America and Gondwana” by Adam K. Huttenlocker, David M. Grossnickle, James I. Kirkland, Julia A. Schultz and Zhe-Xi Luo published in the journal Nature.

2 06, 2018

The Mother of All Dragons – Megachirella

By | June 2nd, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

The Mother of All Dragons – Megachirella wachtleri

A team of international scientists, including palaeontologists from Bristol University, Midwestern University (Arizona) and the University of Alberta, have identified the world’s oldest lizard fossil, permitting fresh insight into the evolution of extant snakes and lizards (Squamata).  Writing in the journal “Nature”, the researchers, including co-author Dr Massimo Bernardi from MUSE – Science Museum, Italy and University of Bristol’s School of Earth Sciences, built the largest dataset of reptiles ever assembled in order to assess where in the evolutionary tree of the Reptilia a fossil from the Dolomites of Italy should be placed.

The Holotype Specimen of Megachirella wachtleri

The origins of the Squamata - The holotype of Megachirella wachtleri.

The holotype of Megachirella wachtleri.

Picture Credit:  MUSE – Science Museum

Megachirella wachtleri

The fossil, consisting of an articulated partial specimen was discovered in marine sediments in the Dolomites of Italy and named Megachirella wachtleri in 2003.  Although, found in marine sediment, the fossil, which represented the front portion of the animal, showed no adaptations to an aquatic existence.  On the contrary, it had strong legs with claws and although small at around twenty centimetres in length, it was probably a capable climber.  It was concluded that the carcass of this reptile had been washed out to sea following a storm.

An analysis in 2013 concluded that Megachirella wachtleri was a member of the Lepidosauromorpha, a group of diapsid reptiles defined as being closer to Squamata than to the Archosauria.  Lepidosaurs include modern snakes and lizards, many extinct forms of reptile and the Order Rhynchocephalia, once very diverse, but now only represented by the tuatara of New Zealand.  This new research, which drew upon an enormous database of skeletal and molecular information about 129 different types of reptile, revealed that Megachirella had characteristics that are only found in the Squamata.  It was concluded that M. wachtleri was a stem squamate – think of it as being the “the mother of all dragons”.

Co-author Dr Randall Nydam of the Midwestern University in Arizona stated:

“At first I did not think Megachirella was a true lizard, but the empirical evidence uncovered in this study is substantial and can lead to no other conclusion.”

The 240-million-year-old fossil, Megachirella wachtleri, is the most ancient ancestor of all modern lizards and snakes discovered to date.  The study also found that geckoes are the earliest crown group squamates not iguanians as previously thought.

A Life Reconstruction of  Megachirella wachtleri

Megachirella wachtleri in the Dolomites 240 million years ago.

A life reconstruction of Megachirella wachtleri.

Picture Credit: Davide Bonadonna

The beautiful illustration of M. wachtleri produced by Davide Bonadonna is featured on the front cover of the journal Nature, which provides details of this scientific study.

The research team conclude that the Squamata probably evolved in the Late Permian and therefore, the ancestors of today’s snakes and lizards survived the most devastating mass extinction event known to science – the end Permian extinction.

Tiago Simões, lead author of the scientific paper and a PhD student at the University of Alberta (Canada), explained:

“The specimen is 75 million years older than what we thought were the oldest fossil lizards in the entire world and provides valuable information for understanding the evolution of both living and extinct squamates.”

10,000 Squamate Species

It has been estimated that there are around 10,000 species of lizards and snakes living today, twice as many different species as mammals.  Despite this modern diversity, scientists did not know much about the early stages of their evolution.

Student Tiago Simões added:

“It is extraordinary when you realise you are answering long-standing questions about the origin of one of the largest groups of vertebrates on Earth.”

Co-author of the study, Dr Michael Caldwell from the University of Alberta, explained that fossils represent the only accurate window into the ancient story of life on our planet.  The new understanding about Megachirella and its significance is but a point in deep geological time, it does tell us things about the evolution of lizards that we simply cannot learn from any of the extant species today.

Co-author Dr Massimo Bernardi from MUSE – Science Museum, Italy and University of Bristol’s School of Earth Sciences, commented upon the importance of such fossil specimens, stating:

“This is the story of the re-discovery of a specimen and highlights the importance of preserving naturalistic specimens in well maintained, publicly accessible collections.”

The scientific paper:

“The Origin of Squamates Revealed by a Middle Triassic Lizard from the Italian Alps” by T. Simões, M. Caldwell, M. Tałanda, M. Bernardi, A. Palci, O. Vernygora, F. Bernardini, L. Mancini and R. Nydam published in the journal Nature.

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

29 05, 2018

Could We Have Got Pterosaurs All Wrong?

By | May 29th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

New Research Challenges Traditional View of Pterosaur Flight

Take a look at a picture of a pterosaur flying and you will see that most illustrations and life-reconstructions of these reptiles depict them travelling through the air with their hind limbs trailing behind them and their back legs wide apart.  However, a new study undertaken by scientists from Brown University (Rhode Island) and the University of California (Berkeley), suggests that we have got this all wrong, pterosaur joints did not permit them to fly with their hind limbs splayed far apart.

Pterosaurs in the Air – But Have we got Their Hind Limbs in the Wrong Position?

Pterosaurs of the Late Cretaceous (Morocco).

Six new species of Pterosaur have been recently identified from Moroccan fossils but if we depict them flying, the convention is to show the hind limbs spread far apart.

Picture Credit: John Conway

We Look at the Bones, But What About the Ligaments?

Flying with the hind limbs splayed out, is a posture adopted by most bats when they take to the air.  Ever since the first flying reptiles were described and illustrated, these Archosaurs have been depicted in the same way.  However, this new research, published in the Proceedings of the Royal Society B (biology), suggests that ligaments would restrict joint movement and pterosaurs and the volant dinosaurs such as Microraptor, could not have flown in the same way as bats.

Lead author of this study, Armita Manafzadeh, a PhD student at Brown University commented:

“Most of the work that’s being done right now to understand pterosaur flight relies on the assumption that their hips could get into a bat-like pose.  We think future studies should take into account that this pose was likely impossible, which might change our perspective when we consider the evolution of flight in pterosaurs and dinosaurs.”

The “Classical” Pterosaur Flying Posture

Investigating the flying posture of the Pterosauria.

The “bat-like” posture of the hind limbs of pterosaurs, may not have been anatomically possible.

Picture Credit: Armita Manafzadeh

The study undertaken in collaboration with Kevin Padian (University of California), attempted to infer the range of motion of joints in a way that takes into account the soft tissues such as ligaments surrounding the joint.  Usually, soft tissue such as ligament and cartilage does not fossilise, so palaeontologists have to work out joint motion from just the bones alone.  The pair of scientists set out to examine the joint movement of modern dinosaurs – birds, to test the extent to which ligaments influence joint motion.

Chickens at a Grocery Store

Student Manafzadeh explained that the idea started with grocery store chickens:

“If you pick up a raw chicken at the grocery store and move its joints, you’ll reach a point where you will hear a pop.  That’s the ligaments snapping, but if I handed you a chicken skeleton without the ligaments, you might think that its joints could do all kinds of crazy things,  So, the question is, if you were to dig up a fossil chicken, how would you think its joints could move and how wrong would you be?”

Quetzalcoatlus – A Giant Pterosaur Takes to the Air (Note the Splayed Out Back Legs)

Quetzalcoatlus takes to the air

Quetzalcoatlus takes to the air.

Picture Credit: Everything Dinosaur

Dead Quails and X-ray Images

Chickens may be easy to acquire, but for this scientific study, dead quails were used in order to assess joint mobility in a three-dimensional way, rather than just referring to the bones.  Birds are the closest living relatives to the extinct pterosaurs and the non-avian dinosaurs.  Birds (Aves), the Pterosauria and the Dinosauria are members of the Archosauria clade.  This clade is  usually divided into two distinct branches, on one branch (Crurotarsi), are the crocodilians and their ancestors plus several other extinct lineages such as the phytosaurs.  The second branch (Avemetatarsalia) groups all the reptiles more closely related to birds than crocodilians.  A sub-group of the Avemetatarsalia is the Ornithodira, which specifically nests the Pterosauria and their ancestors and the Dinosauria and their ancestors, plus the descendants of dinosaurs – birds, together.  Hence, the use of quail limbs to assess the range of movement and joint mobility.

The skin and muscle surrounding the joints was cut away and once the hip joints were exposed, the scientists manipulated them taking X-ray images to assess the likely range of motion.  By doing this, they could determine the exact positions of the bones in poses where the ligaments restricted and then prevented further joint movement.

Mapping Out the Joint Movements of Ornithodirans

This technique enabled Manafzadeh to map out the range of motion of the quail hip with ligaments attached.  She then compared this range of motion to what was inferred when the bones were considered in isolation.  For the bones-only poses, Manafzadeh used traditional criteria that palaeontologists often employ — stopping where the two bones hit each other and when the movement pulled the thigh bone out of its socket.

This experiment revealed that over 95 percent of the joint positions that seemed plausible with bones alone were actually impossible when the ligaments were attached.

Mapping Out the Range of Motion in Quail Hips

Mapping the movement of Archosaur limbs.

Mapping the range of movement in quail hind limbs to assess the movement of Ornithodiran limbs.

Picture Credit: Armita Manafzadeh

The Implications for Pterosaurs and the Maniraptora

The team’s next move was to calculate how the range of motion in living birds might correlate to the range of motion expected for extinct pterosaurs and those members of the Maniraptora, such as Microraptor that are believed to have been able to fly.  The assumption has long been that these creatures flew in a similar way to bats.  That is partly because the wings of pterosaurs were made of skin and supported by an elongated fourth finger, which is superficially similar to the wings of bats.  Bat wings are also connected to their hind limbs, which they splay out widely during flight. Many palaeontologists, Manafzadeh says, assume pterosaurs and four-winged dinosaurs did the same.  But this new study suggests that pose was impossible.

In quail, a bat-like hip pose seemed possible based on bones alone, but outward motion of the thigh bone was inhibited by one particular ligament, a ligament that’s present in a wide variety of birds and other reptiles related to the Pterosauria.  Consequently, in the absence of extraordinary evidence to the contrary, this analysis casts doubt on the “bat-like” hip pose traditionally inferred for pterosaurs and basal Maniraptorans and underscores the point that reconstructions of joint mobility based on manipulations of bones alone can be misleading.

To achieve a “bat-like” flying posture, the ligament would have to stretch 63 percent more than the quail ligament can, the implication is that we have been illustrating flying reptiles and flying dinosaurs all wrong.

A Model of a Volant Dinosaur (Microraptor)

A Microraptor flight model.

Up, up and away!  A model of the four-winged dinosaur Microraptor in flight, note the splayed-out position of the back legs.

Picture Credit: Solent

In addition to challenging traditional views about flight in pterosaurs and early birds, the research also provides new ways of assessing joint mobility for any joint of any extinct species by looking at its living relatives.

The scientific paper: “ROM Mapping of Ligamentous Constraints on Avian Hip Mobility: Implications for Extinct Ornithodirans” by Armita R. Manafzadeh, Kevin Padian published in the Proceedings of the Royal Society B

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

28 05, 2018

Fossil Flakes and Dinosaur Dandruff

By | May 28th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Dinosaur and Early Bird Dandruff

A team of international scientists led by researchers from University College Cork (Ireland), have discovered the fossilised remains of skin flakes from feathered dinosaurs and primitive birds that lived during the Early Cretaceous.   The flakes of skin, preserved amongst the plumage of the feathered creatures, has provided evidence on how dinosaurs shed their skin.  Unlike many reptiles alive today, animals such as lizards and snakes, which shed their skin as a single piece or as several large pieces, it seems that basal birds and non-avian dinosaurs shed small epidermal flakes just like modern birds and mammals and that includes us with our dandruff.

Preserved Soft Tissue Evidence – Flakes of Skin in Maniraptoran Dinosaurs and the Basal Bird Confuciusornis

Fossils of shed dinosaur skin and a basal bird (Confuciusornis).

Phosphatised soft tissues in non-avian Maniraptoran dinosaurs and a basal bird.

Picture Credit: Nature Communications

The photographs above (labelled a to h), show scanning electron microscope generated images of tissue in the Early Cretaceous Aves C. sanctus (a,e and f), the dromaeosaurid Sinornithosaurus (S. millenii) in photographs c and h, along with the Therizinosaur Beipiaosaurus (B. inexpectus), photos b and g.  The photograph labelled d, is a view of epidermal flakes preserved in association with the fossilised remains of Microraptor, which along with Sinornithosaurus is believed to have been capable of flight or at least gliding.  Studying the constituents of flakes of dinosaur skin, which come from animals that might have been volant, is very important.  Palaeontologists can compare these flakes to living birds which are capable of powered flight.  These flakes, in turn can be examined in relation to the flakes of terrestrial feathered dinosaurs such as Beipiaosaurus.  Any differences in the composition of these flakes might provide scientists with further information on the aerial abilities of dinosaurs such as Microraptor and Sinornithosaurus.

The scientists include researchers from the Chinese Institute of Vertebrate Palaeontology and Palaeoanthropology, Bristol University, Linyi University (China), the Open University as well as Queen Mary University (London) and the University College Dublin (Ireland).   They studied the fossil cells and dandruff from a range of Early Cretaceous Theropods and compared the skin flakes to those of living, extant birds.

Lead author of the research, Dr Maria McNamara (University College Cork), stated:

“The fossil cells are preserved with incredible detail,  right down to the level of nanoscale keratin fibrils.  What’s remarkable is that the fossil dandruff is almost identical to that in modern birds – even the spiral twisting of individual fibres is still visible.”

Getting to Grips with Corneocytes

The scientists used a scanning electron microscope (SEM), to examine the beautifully preserved, but microscopic fossilised fragments of skin associated with three feathered dinosaur specimens (Microraptor, Beipiaosaurus and Sinornithosaurus) and one Early Cretaceous bird Confuciusornis (Confuciusornis sanctus).  All of these fossils are associated with the Jehol biota of north-eastern China.

A Pair of Fossilised Confuciusornis (Liaoning Province) Showing the Two Known Body Plans for these Ancient Birds

Confuciusornis fossil birds.

A pair of Confuciusornis fossil birds (Liaoning Province).

Just like our own flakes of skin, our dandruff, the fossil flakes consist of tough cells known as corneocytes.  These cells are full of protein fibres (keratin), such was the quality of preservation that the SEM analysis was able to identify bundles of these fibres and even to hone in on single strands.

Scanning Electron Micrographs of Skin Flakes Associated with C. sanctus

Fossilised skin flakes of Confuciusornis.

Ultrastructure of the soft tissues in Confuciusornis.

Picture Credit: Nature Communications

The photographs (above) show highly magnified images of the skin flakes associated with Confuciusornis.  Closely packed polygons can be observed (a and b), whereas (c) shows a detailed view of the polygons and the first signs at this magnification of the bundles of fibrous keratin.  The drawing (d) interprets the bundles as more darkly shaded areas in the central part of each polygon.  Photograph (e) shows the area that was more closely observed (f and g) indicating the presence of fibres, whereas, (h) shows the fibrous bundle associated with a skin flake in an extreme close-up view.  Helical coiling of the tiny fibres is shown (picture i) and photographs j and k show polygons having been deformed by some form of stretching.

These structures were then compared to the flakes of skin associated with living birds, in this case, male specimens of Zebra Finches (Taeniopygia guttata) and the Java Sparrow (Lonchura oryzivora).  In addition, the fossil evidence was compared to the moulted, downy feathers of a male American Pekin Duck (Anas platyrhynchos domestica).

Clues About Dinosaur Metabolism

This research suggests that this ability to constantly shed skin evolved sometime in the late Middle Jurassic, around the same time as a host of other skin features evolved.  The feathered epidermis of dinosaurs acquired many, but not all, anatomically modern attributes close to the base of the Maniraptora clade.

Dr McNamara explained:

“There was a burst of evolution of feathered dinosaurs and birds at this time, and it’s exciting to see evidence that the skin of early birds and dinosaurs was evolving rapidly in response to bearing feathers.”

Co-author, Professor Mike Benton (Bristol University), commented:

“It’s unusual to be able to study the skin of a dinosaur, and the fact this is dandruff proves the dinosaur was not shedding its whole skin like a modern lizard or snake but losing skin fragments from between its feathers.”

Corneocytes in Living Birds

Corneocytes in living birds

Corneocytes in extant birds.

Picture Credit: Nature Communications

The four photographs above, show scanning electron micrographs of shed skin flakes in living birds.  Note the polygonal structure (a), which is reminiscent of the shapes seen when the corneocytes of extinct dinosaurs and birds were studied.  Photograph (b) shows a central depression in the cell associated with a pycnotic nucleus, whilst photographs (c and d) show skin flakes stuck to the bird’s feathers.

Modern birds have very fatty corneocytes with loosely packed keratin, which allows them to cool down quickly when they are flying for extended periods.  The corneocytes in the fossil dinosaurs and birds, however, were packed with tightly bundled keratin, suggesting that the extinct creatures didn’t get as warm as modern birds, presumably because they couldn’t fly at all or for as long.  This suggests that Confuciusornis did not fly that well, if probably flew in short bursts, but may not have been capable of making prolonged flights.  The lack of fatty corneocytes in those dinosaurs which are thought to have had some aerial ability (Microraptor and possibly Sinornithosaurus), sheds doubt on whether they were truly volant.

Could Some Dinosaurs Like Microraptor Fly?

Microraptor dinosaur model.

A member of the Dromaeosauridae sub-family the Microraptorinae, but could these dinosaurs fly?  The absence of fatty corneocytes suggests a lower metabolism than with extant birds..

Picture Credit: Everything Dinosaur

Everything Dinosaur acknowledges the assistance of a press release from the University College Cork (Ireland) in the compilation of this article.

The scientific paper: “Fossilised Skin Reveals Coevolution with Feathers and Metabolism in Feathered Dinosaurs and Early Birds” by Maria E. McNamara, Fucheng Zhang, Stuart L. Kearns, Patrick J. Orr, André Toulouse, Tara Foley, David W. E. Hone, Chris S. Rogers, Michael J. Benton, Diane Johnson, Xing Xu and Zhonghe Zhou published in Nature Communications.

25 05, 2018

How Birds Survived the Cretaceous Mass Extinction Event

By | May 25th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Ground Dwelling Birds Survived Asteroid Strike

One of the fascinating conundrums about the end Cretaceous extinction event is how did the avian dinosaurs (birds) survive, but their very close cousins the non-avian dinosaurs, animals such as Tyrannosaurus rex, Triceratops and Edmontosaurus fail to make it through this calamitous time in Earth’s history?  A team of international researchers, writing in the journal “Current Biology” have put together a fascinating explanation as to why we have birds today, but no other Theropods, or indeed any other representatives of the Dinosauria.

With the extra-terrestrial impact event some 66 million and 38 thousand years ago (plus or minus 11,000 years), the ecosystems on our planet were devastated.  Whether this single, huge impact was the sole cause of the mass extinction or whether this was the final “coup de grâce” is debatable, however, life would never be the same again.

Using a variety of data sources, the team, which included scientists from the University of Bath, the Denver Museum of Nature and Science, Yale University and the Field Museum amongst others, have pieced together what the impact event meant for the Aves.  Their scientific paper suggests that the only kinds of birds to survive the Cretaceous-Palaeogene (K-Pg) extinction were ground- dwellers.

How Our Feathered Friends Survived the Cretaceous-Palaeogene Extinction Event

Ground-dwelling birds survived the extinction event.

Ground-dwelling birds survived the K-Pg extinction event.

Picture Credit: Phillip Krzeminski

Why Did the Birds Survive?

A number of ideas and theories have been proposed to help explain why the birds are around today, but the non-avian dinosaurs are not.  Recently, Everything Dinosaur published an article on a piece of research that suggested that seed-eating may have contributed to the survival of birds during this devastating time in the history of our planet.

To read the article: Seed Eating May Have Helped the Birds Survive

Commenting on the scientific paper, lead author Daniel Field of the Milner Centre for Evolution (University of Bath) stated:

“We drew on a variety of approaches to stitch this story together.  We concluded that the devastation of forests in the aftermath of the asteroid impact explains why tree-dwelling birds failed to survive across this extinction event.  The ancestors of modern tree-dwelling birds did not move into the trees until forests had recovered from the extinction-causing asteroid.”

The Collapse of Forests

The scientists analysed the plant fossil record and identified that the world’s woodlands and forests were virtually wiped out by the extra-terrestrial impact.  Huge forest fires would have raged in the immediate aftermath of the impact and it is likely that much of the world had to endure a period of extensive “acid rain” as a result of the catastrophic event.  In the months, or maybe even tens of years afterwards, our planet could have been blanketed in a cloud of dust and ash.  This would have blocked out the sun and led to the collapse of food chains which relied on photosynthesising plants.

The Impact Event Had Consequences for Virtually All Life on Earth

Earth impact event.

Cataclysmic impact event that led to the extinction of the non-avian dinosaurs but not all the avian dinosaurs.

Picture Credit: Don Davis (Commissioned by NASA)

The scientists look at the record of fossil pollen and spores to assess the types of flora present and how quickly, ferns, flowering plants (angiosperms) and other types of flora recovered after the extinction event.

Plotting the Turnover of Different Types of Flora from Pollen and Spore Counts

Flora turnover at the K-Pg boundary.

Floral turnover evidenced by changes in relative abundance of common pollen taxa across the K-Pg boundary.

Picture Credit: Current Biology with additional annotation by Everything Dinosaur.

The diagram (above), plots the palynological record of the John’s Nose Section in North Dakota, a series of sequential strata laid down before, during and after the extinction event.  It helps to plot the demise of different types of plant and their recovery (floral turnover), as evidenced by changes in relative abundance of common pollen taxa across the K-Pg boundary.  Note, the “fern spike” recorded not long after the extinction event, ferns are usually the first type of plant to recover from natural disasters today, as evidenced by their ability to re-populate areas destroyed following volcanic activity.

Evolutionary Relationships of Living Birds

The research team examined the evolutionary relationships of extant birds and their ecological habits to map how bird ecology has changed over time.  The data revealed that the most common ancestor of all living birds, all the bird lineages that survived the K-Pg extinction event, most likely were ground-dwellers.  In contrast, many Aves that lived at the end of the age of dinosaurs (and there were lots of them), exhibited tree-dwelling, arboreal habits.  These species did not survive the mass extinction event and therefore they have no direct living descendants around today.

Daniel Field added:

“Today, birds are the most diverse and globally widespread group of terrestrial vertebrates, there are nearly 11,000 living species.  Only a handful of ancestral bird lineages succeeded in surviving the K-PG mass extinction event 66 million years ago and all of today’s amazing living bird diversity can be traced to these ancient survivors.”

The researchers conclude that their findings shed light on the fundamental influence major events in the history of our planet have on the evolution of living things.  The team hope to build on this initial research and to explore the timing of the recovery of the vegetation and to develop a better understanding of the early radiation of the birds.  After all, those lucky survivors inherited a brave new world, devoid of non-avian dinosaurs and many other terrestrial and marine organisms too.

The scientific paper: “Early Evolution of Modern Birds Structured by Global Forest Collapse at the End-Cretaceous Mass Extinction” by Daniel J. Field, Antoine Bercovici, Jacob S. Berv, Regan Dunn, David E. Fastovsky, Tyler R. Lyson, Vivi Vajda and Jacques A. Gauthier published in the journal Current Biology.

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