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/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.

11 09, 2017

500 Million-Year-Old Trace Fossils Shed Light on Animal Evolution

By | September 11th, 2017|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles|0 Comments

Tracing the Traces of Early Animal Life

Darwin was aware of the problem, Huxley and Owen had considered it too.  The American Charles Walcott, in 1909*, literally stumbled across evidence to support the idea of a bizarre array of early animal forms, but the fossil evidence that helps to pinpoint and then map the evolution of the Kingdom Animalia in deep geological time, is scarce to say the very least.  How and when did the first animals evolve?  What type of creatures were they?  These are the questions that taxed the minds of some of the greatest scientists in history, now, thanks to some new research published today, the way we think about how all animals evolved on Earth might just change.

Scientists have discovered microscopic traces of animal life more than half-a-billion years old.  The international team, including scientists from Manchester University, have identified trace fossils left by some of the first ever organisms capable of active movement.

Plotting the Evidence of Ancient Burrowing Creatures

The first animals (trace fossils).

Evidence of the first animals (burrows and borings).

Picture Credit: Manchester University

The picture above might look like a Jackson Pollock, but the image shows a computer generated, three-dimensional model of the trace fossils found by the scientists.  Trace fossils preserve evidence of the activity of organisms.  They are often the only evidence palaeontologists have for extinct animals whose bodies lacked any hard parts.  No physical remains of the microscopic worms that made these burrows have been found, but the researchers suggest that they were made by a type of nematoid-like worm, an animal with bilateral symmetry, making these organisms more closely related to Chordates (animals with notochords and spinal columns), than creatures like jellyfish and corals.

The fossils were discovered in sediment in the Corumbá region of western Brazil, close to the border with Bolivia.  The burrows are extremely small.  They measure from less than fifty to six hundred micrometres or microns (μm) in diameter.  That means the tiny creatures that made them were similar in size to a human hair, which can range from forty to three hundred microns wide.  One micrometre is just one thousandth of a millimetre.

The Research Team Carefully Mapped the Intricate Burrows in the Ancient Sediment

Ancient roundworm trace fossils.

Trace fossils indicate the first animals capable of independent movement.

Picture Credit: Manchester University

Commenting on the significance of this research, Dr Russell Garwood (University of Manchester School of Earth and Environmental Sciences), stated:

“This is an especially exciting find due to the age of the rocks, these fossils are found in rock layers which actually pre-date the oldest fossils of complex animals – at least that is what all current fossil records would suggest.”

The Ediacaran-Cambrian Transition

The fossils found date back to a geological and evolutionary period known as the Ediacaran–Cambrian transition.  This was when the Ediacaran Period, which spanned 94 million years from the end of the Cryogenian Period, 635 million years ago, moved into the Cambrian Period around 541 million years ago.  To put that into context, dinosaurs lived between 235 and 66 million years ago in the Mesozoic Era and our human species (H.sapiens), may have been present on this planet for around 250,000 years or so.

Dr Garwood explained:

“The evolutionary events during the Ediacaran–Cambrian transition are unparalleled in Earth history.  That’s because current fossil records suggest that many animal groups alive today appeared in a really short time interval.”

The scientists suggest these burrows were created by “nematoid-like organisms”, similar to a modern-day roundworm, that used an undulating locomotion to move through the sediment, leaving these trace fossils behind.  This is important because current DNA studies, known as “molecular clocks”, which are used to estimate how long ago a group animals originated, suggests the first animals appeared before these trace fossils.  The research paper published in the academic journal “Nature Ecology and Evolution”, demonstrates that these trace fossils pre-date similar animals known from the fossil record.

Luke Parry, the lead author of the paper (Bristol University) stated:

“Our new fossils show that complex animals with muscle control were around approximately 550 million years ago, and they may have been overlooked previously because they are so tiny.  The fossils that we describe were made by quite complex animals that we call bilaterians.  These are all animals that are more closely related to humans, rather than to simple creatures like jellyfish.  Most fossils of bilaterian animals are younger, first appearing in the Cambrian period.”

*It was the American Charles Walcott who discovered the Burgess Shale deposits of British Columbia, that first provided palaeontologists with a window into the radiation and diversity of the Animalia during the Middle Cambrian.  The unique taphonomy of these shales permitted the preservation of a multitude of marine invertebrates including thousands of specimens of soft-bodied creatures.

Mapping the Extensive Network of Trails

Ancient trace fossils.

The different colours mark different burrows.

To find such tiny fossils the team used X-ray microtomography, a special technique that uses X-rays to create a virtual, three-dimensional model of something without destroying the original object.

Paper Reference – ‘Ichnological evidence for meiofaunal bilaterians from the terminal Ediacaran and earliest Cambrian of Brazil ‘ is being published in Nature Ecology & Evolution – DOI 10.1038/s41559-017-0301-9

Further Reading:

Cambrian worm discovery: It was a Worm’s World Back in the Cambrian

A potential transitional fossil between worms and Arthropoda: Transitional “Cactus-like” Fossil Between a Worm and an Arthropod

9 09, 2017

Has Human Evolution Tripped Us Up?

By | September 9th, 2017|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles|0 Comments

5.7 Million-year-old Hominin Footprints on Crete

The chance discovery of hominin fossilised footprints on the Mediterranean island of Crete, has challenged the accepted theory of human evolution.  The footprints, which have been dated to around 5.7 million years ago, were formed when all other hominins known to science were restricted to Africa and they had much more ape-like feet.  If the series of tracks prove to be accurately dated, then this challenges the idea that hominins (those species more closely related to us than they are to a chimpanzee), evolved in Africa.  Has someone just rocked the “cradle of humanity”?

A Photograph of the Tracks (Ancient Hominin Footprints)

Hominin fossil footprints from Crete.

Fossilised hominin footprints from Crete.

Picture Credit: Andrzej Boczarowski

The Out of Africa Theory

With the discovery of the Laetoli footprints in Tanzania in the mid 1970’s (believed to have been made by a small group of Australopithecus afarensis), which were formed some 3.7 million years ago, our species (H. sapiens) and our direct ancestors were thought to have originated in Africa.  These footprints, show very human-like feet with a distinctive shape, a big toe and a human gait.   The gait of these early humans was “heel-strike” (the heel of the foot hits first) followed by “toe-off” (the toes push off at the end of the stride), the same way that modern humans walk.  Early hominins were thought to have remained isolated in Africa before dispersing to Europe and Asia, hundreds of thousands of years after they first evolved.  The discovery of approximately 5.7 million-year-old human-like footprints from Crete, published online this week by an international team of researchers, including scientists from Uppsala University (Sweden), overturns this rather simple picture and suggests a more complicated evolutionary path for our ancestors.

A Close View of One of the Footprints (right foot)

Fossilised hominin footprint from Crete

A fossilised hominin footprint from Trachilos (western Crete). The right footprint is estimated to be 5.7 million-years-old.

Picture Credit: Andrzej Boczarowski

The picture above shows a close-up of one of the footprints, the big toe can be clearly seen.  Our feet have a very distinctive shape.  We have five short toes without claws, the hallux (big toe), is much larger than the other toes and our foot has a long sole.  The feet of the great apes, are very different.  They resemble a human hand with a thumb-like hallux that sticks out to the side.  The Laetoli footprints, ascribed to A. afarensis, are quite similar to those of modern humans except that the heel is narrower and the sole lacks a proper arch.  The 4.4 million-year-old Ardipithecus ramidus from Ethiopia, the oldest hominin known from reasonably complete fossils, has an ape-like foot.   The researchers who described Ardipithecus argued that it is a direct ancestor of later hominins, implying that a human-like foot evolved later.

The Trachilos Tracks

The newly described tracks from Trachilos in western Crete bear a close resemblance to a human footprint.  The big toe has similar morphology and there seems to be a distinct “ball” on the sole, which is absent in primates.  The sole of the foot is proportionately shorter than in the Laetoli prints, but it has the same general form.  The prints do look as if they were made by a hominin.

The Foot of a Great Ape (Note the Position of the Big Toe)

A photograph of the foot of an ape.

The foot of an ape.

Approximately fifty tracks were made when bipeds walked across a sandy area and although many large apes are known from the Late Miocene of Europe, no hominin was thought to have migrated into Europe for millions of years after the tracks were made.

Professor Per Ahlberg (Uppsala University), the lead author of the study commented:

“What makes this controversial is the age and location of the prints.”

At approximately 5.7 million years, they are younger than the oldest known fossil hominin, Sahelanthropus from Chad, and contemporary with Orrorin (O. tugenensis), from Kenya, but more than a million years older than Ardipithecus ramidus with its ape-like feet.

This fossil find throws into question the hypothesis that Ardipithecus is a direct ancestor of later hominins.  In addition, until this year, all fossil hominins older than 1.8 million years (the age of early Homo fossils from Georgia), came from Africa, leading most researchers to conclude that this was where the group evolved.  However, the Trachilos footprints are securely dated using a combination of foraminifera (marine micro-fossils) from over and underlying bedding planes, plus the fact that they lie just below a very distinctive sedimentary rock formed when the Mediterranean Sea temporarily evaporated around 5.6 million years ago.  Coincidentally, earlier this year, another group of researchers, led by Professor Madelaine Böhme of the University of Tübingen, (Germany), writing in the Journal PLOS One, reinterpreted the fragmentary 7.2 million-year-old primate Graecopithecus freybergi from Greece and Bulgaria as a hominin.

Professor Ahlberg added:

“This discovery challenges the established narrative of early human evolution head-on and is likely to generate a lot of debate.  Whether the human origins research community will accept fossil footprints as conclusive evidence of the presence of hominins in the Miocene of Crete remains to be seen.”

The eastern Mediterranean in the Late Miocene consisted of extensive, arid grasslands, the Sahara Desert did not exist and Crete was still part of the Greek mainland.  Early hominins could have ranged along this habitat moving from Africa to south-eastern Europe, with one group leaving their footprints on the shores of the Mediterranean that would one-day form part of the island of Crete.

The scientific paper: Possible Hominin Footprints from the Late Miocene (c. 5.7 Ma) of Crete?   Gierlinski, G. D. et al. 2017. published in the Proceedings of the Geologists’ Association.

Everything Dinosaur acknowledges the help of an Uppsala University press release in the compilation of this article.

4 08, 2017

Amazing Armoured Dinosaur Fossil Reveals Countershading

By | August 4th, 2017|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Borealopelta markmitchelli – Big but There was Something Bigger and Very Nasty Out There!

You’re about as heavy as a Ford Focus, your body is covered in bony armour and you have lethal spikes running down your flanks, including a pair of wicked-looking shoulder spines, yet you rely on camouflage to help keep you safe.  That’s the conclusion reached by an international team of scientists as they have studied the best-preserved armoured dinosaur ever found.  Borealopelta might have weighed in excess of 1.3 tonnes and measured more than 5.5 metres long, but it relied on countershading to help hide it from predatory dinosaurs.

This is an amazing piece of research, perhaps, more amazingly, this research implies that for a dinosaur described as a “walking tank”, there was one or maybe several super-sized meat-eating dinosaurs that despite the heavy armour, it was best to hide away from.  Trouble is, palaeontologists can only speculate about what sort of multi-tonne Theropod might have been the stuff of nightmares for Borealopelta, we simply don’t know.

An Illustration of the Armoured Dinosaur Borealopelta (B. markmitchelli)

 Borealopelta markmitchelli illustrated.

An illustration of the nodosaurid Borealopelta markmitchelli.

Picture Credit: Julius Csotonyi

The First Line of Defence Not to be Seen in the First Place

Writing in the academic journal “Current Biology”, the researchers, which included Caleb Brown and Donald Henderson (Royal Tyrrell Museum, Alberta, Canada) along with Jakob Vinther (Bristol University), Ian Fletcher (Newcastle University) and colleagues from the Massachusetts Institute of Technology, conclude that Borealopelta possessed countershading to help camouflage it and avoid detection from sharp-eyed Theropod dinosaurs.

Using chemical analysis of organic compounds in the horns and skin to infer the dinosaur’s pigmentation pattern, the scientists found that the skin exhibited countershading, a common form of camouflage in which an animal’s underside is lighter than its back.  The top part of the animal was coloured a reddish-brown.  The russet colouration contrasted with the lighter shaded, paler underbelly.

Dr Vinther, an expert on the detection of colour signals within the fossil record commented:

“We found a lot of sulphur bearing organic compounds, which we later could confirm was evidence for reddish brown colouration.”

The Superbly-Preserved Holotype Specimen of Borealopelta markmitchelli

Borealopelta markmitchelli holotype.

Borealopelta markmitchelli fossil (scale bar = 10 cm).

Picture Credit: Royal Tyrrell Museum

A Sleeping Armoured Giant

The researchers used two mass spectroscopic techniques called Time of Flight Secondary Ion Mass Spectroscopy and Pyrolysis Gas Chromatography Mass Spectroscopy to reveal the armoured dinosaurs’ colouration.  Such procedures were only possible due to the exceptional preservation of the specimen, which is currently on display at the Royal Tyrrell Museum.  The fossil material was discovered in 2011 at the Suncor Millennium Mine, in north-eastern Alberta, during the removal of overburden.  This was the first dinosaur to be found in these sediments.

To read more about the fossil discovery: Oil Worker Digs Up Dinosaur

The strata represent sediments laid down in an offshore marine environment.  The carcass sank to the bottom of the seabed, its back hitting the seafloor hard enough to deform the underlying sedimentary layers.  The specimen was preserved in exquisite detail and is almost complete.  The articulated skeleton gives the impression that this armoured giant is merely sleeping and likely to be roused at any moment.

Holotype Specimen of B. markmitchelli

Borealopelta specimen.

The sleeping giant Borealopelta from north-eastern Alberta.

Picture Credit: Royal Tyrrell Museum

The Implications of the Countershading

Borealopelta comes from the Wabiskaw Member of the Clearwater Formation, these rocks were laid down in the Early Cretaceous (Albian faunal stage).  Marine reptiles are known from these rocks, but this is the first time that a dinosaur has been found, the body of Borealopelta probably floated out to sea, an example of “bloat and float”.  The discovery of countershading in such a large animal begs the question, what sort of dinosaur was Borealopelta trying to hide from?

Countershading is a common evolutionary strategy seen in many prey animals today.  However, no extant animal exceeding one tonne in weight is counter shaded.  Lots of ungulates possess countershading but they are all far smaller than Borealopelta.  The researchers assessed the body mass of typical mammals that have such camouflage and compared them to the body weights of the carnivorous mammals that predate them.  The scientists concluded that as prey body size increases within typical terrestrial mammalian prey, so the number of species demonstrating countershading decreases.  Once you get to be the size of a rhino or an elephant, countershading in extant, terrestrial ecosystems is not present.  However, in the Early Cretaceous, things were very different.

A Chart Illustrating the Loss of Countershading as Body Mass Increases (Terrestrial Mammals)

A chart illustrating counter-shading compared to body size.

As body size increases so the amount of countershading seen in terrestrial mammals decreases.

Picture Credit: Current Biology

The chart above shows the relative proportion of species that exhibit countershading.  The diagonally hatched area represents the mass above which significant predation of adults does not occur.  Animals illustrated above the chart are representative taxa within each mass bin, the species names in italics at the top indicates the body masses of the largest carnivores (Canivora).

Dr Vinther explains:

“Although countershading is common, our findings come as surprise because Borealopelta’s size far exceeds that of counter shaded animals alive today.  It suggests the dinosaur was under enough pressure from predators to select for concealment.  This means that the Cretaceous period was a really scary time to be around in.  Large Theropod dinosaurs with excellent colour vision would have made life stressful for many a dinosaur, both big and small.”

What was Borealopelta trying to Hide from?

As no other dinosaur remains have been found in the Wabiskaw Member, the large, meat-eating dinosaurs Borealopelta tried to hide from can only be speculated.  Huge Theropod footprints found in rocks of a similar age and nearby formations in northern Alberta and British Columbia can hint at what sort of fearsome creature shared Borealopelta’s world.  For example, substantial, three-toed dinosaur tracks from the Cedar Mountain Formation of eastern Utah have been described and assigned to the ichnogenus Irenesauripis.  Some of these tracks are nearly ninety centimetres in length and the huge claw marks indicate that whatever dinosaur made these tracks, it was a formidable predator.  The authors of this study suggest that the apex predators were probably allosaurid/carcharodontosaurid taxa and suggest something like the twelve-metre-long Acrocanthosaurus, fossils of which are found in similarly-aged formations further south.

An Illustration of an Acrocanthosaurus (A. atokensis)

Papo Acrocanthosaurus.

The Papo Acrocanthosaurus dinosaur model.

Picture Credit: Everything Dinosaur

Heavily armoured dinosaurs were camouflaged to avoid being spotted by a predator, but what sort of predator is open to question.  Perhaps, in a remote part of British Columbia, the fossil remains of an entirely new type of Theropod dinosaur are awaiting discovery…

“Northern Shield and 7,000 Hours of Painstaking Work

The genus name means “northern shield” a reference to the latitude of the fossil discovery, whereas, the species name honours museum technician Mark Mitchell who spent more than 7,000 hours carefully removing the fossil from the surrounding rock, one grain at a time.  Researchers are now examining the preserved gut contents to find out the nature of its last meal, and working to characterise the body armour in even greater detail.

Comparing Borealopelta to Other Well-Preserved Ankylosaurs

Ankylosaur armour comparisons.

Borealopelta armour compared to other Ankylosaurs.

Picture Credit: Current Biology

The picture above shows a time-calibrated strict consensus tree showing the position of Borealopelta markmitchelli within the Ankylosauria, with representative well-preserved Ankylosaurs provided for comparison.  In this analysis, Borealopelta is regarded as the sister taxon of Pawpawsaurus, also from the Albian faunal stage of the Cretaceous.

Scale bar = 1 metre

(A) Kunbarrasaurus, (QM F18101).

(B) Euoplocephalus, (NHMUK 5161).

(C) Sauropelta, (AMNH 3035 and (3036 composite).

(D) Borealopelta, (TMP 2011.033.0001)

(E) Edmontonia, (AMNH 5665).

The scientific paper: “An Exceptionally Preserved Three-Dimensional Armoured Dinosaur Reveals Insights into Coloration and Cretaceous Predator-Prey Dynamics” by Caleb M. Brown, Donald M. Henderson, Jakob Vinther, Ian Fletcher, Ainara Sistiaga, Jorsua Herrera and Roger E. Summons published in Current Biology.

To read an article on an earlier study regarding the counter-shading of Psittacosaurus: Calculating the Countershading of Psittacosaurus

8 07, 2017

A Time for Digging Up Dinosaurs

By | July 8th, 2017|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Geology, Main Page, Palaeontological articles|0 Comments

Field Teams Prepare to Explore Northern Latitudes

High summer in the northern hemisphere, most teaching programmes may have come to an end but for many palaeontologists, this is their busiest time of year.  The months of July and August represent the best times to explore some of the more remote and difficult to access vertebrate fossil sites.  Take for example, Dr Anthony Fiorillo from the Perot Museum of Nature and Science (Dallas, Texas).  He and his colleagues are busy organising field work in the Aniakchak National Monument (Alaska), area in a bid to learn more about polar dinosaurs.  The summer months represent the only time that scientists have to work at such remote and inaccessible sites, as the weather for once, is on their side.  Palaeontologists will be taking advantage of the near 24-hours of daylight in northern latitudes to further explore the unique prehistoric environments that for most of the year are simply inaccessible.

Dr Tony Fiorillo at Work in the Field

Dr Fiorillo (Perot Museum of Nature and Science)

Dr Anthony Fiorillo in the field ready to dig up dinosaurs.

Picture Credit: Perot Museum of Nature and Science

Dinosaurs of Northern Latitudes

The Late Cretaceous exposures in Alaska provide a record of life at very high latitudes as the age of dinosaurs was drawing to a close.  Just like the herds of migratory herbivorous dinosaurs, which would have fed around the clock, the scientists will be taking advantage of the very long days to get as much work done as possible.  The field team hope to revisit a number of locations in the Aniakchak National Monument in a bid to collect more data on the hundreds of dinosaur tracksites that have been discovered.  These tracks and individual dinosaur footprints provide a unique insight into the ancient palaeofauna, an opportunity to further explore the lives of polar dinosaurs.  In 2014, Everything Dinosaur wrote an article summarising some of the work undertaken by Dr Fiorillo and his colleagues as they interpreted a substantial number of duck-billed dinosaur tracks.  These trace fossils helped the researchers to better understand how these giant, herbivorous dinosaurs moved around in herds: Duck-Billed Dinosaurs Moved Around in Herds just like Elephants. Over the years, researchers from the Perot Museum of Nature and Science have made a very important contribution to research into dinosaur populations that lived (and seemed to thrive) at high northern latitudes.

Commenting on the significance of their work, Dr Fiorillo stated:

“At the start of every one of these expeditions, the adrenaline is pumping.  We are so excited to get back out there.  I fully expect that we will find dozens of footprints and we will learn a little bit more about the environment in which these dinosaurs lived.”

Nanuqsaurus hoglundi and Pachyrhinosaurus perotorum

Staff at the Perot Museum of Nature and Science, along with their collaborators from other institutions have been instrumental in helping to improve our understanding of the polar dinosaurs and the palaeoenvironment.  For example, a third species of Pachyrhinosaurus (P. perotorum) has been erected thanks to Alaskan fossil discoveries.

A Skeleton of the Horned Dinosaur Pachyrhinosaurus

Pachyrhinosaurus dinosaur exhibit.

A large horned dinosaur with a huge skull (Pachyrhinosaurus).

With all that plant food and the long summer days, Alaska might have been a paradise, albeit a chilly one for plant-eating dinosaurs.  However, they did have to contend with some particularly nasty predators, over-sized dromaeosaurids for example and perhaps, even more surprisingly a “polar” Tyrannosaur.  In 2006, a research team led by Dr Anthony Fiorillo and his colleague Dr Ronald Tykoski, also from the Perot Museum of Nature and Science discovered the fossils of a carnivorous dinosaur that was later named Nanuqsaurus hoglundi.

To read more about this fossil discovery: An Update on “Polar Bear Lizard”

We wish all field teams every success and we hope that they have a safe, rewarding and very satisfactory field season.

To read more about the discovery of Pachyrhinosaurus perotorum an article first published in 2011: A New Species of Pachyrhinosaurus is Announced

22 06, 2017

Baru – New Information on Australia’s Ancient “Super Croc”

By | June 22nd, 2017|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

New Specimens of Extinct Crocodylian Baru Described

Australia might be home to some very unusual flora and fauna, but ever since the break-up of the ancient super-continent of Gondwana and the resulting separation of Australia from Antarctica during the Late Cretaceous, this substantial landmass has been isolated.  This isolation has enabled the development of unique ecosystems, many of which included super-sized animals much larger than those found in Australia today.

A paper published in the on-line open access journal PeerJ provides new information on one such ancient Australian resident, a genus of broad-snouted crocodile that probably specialised in ambushing large vertebrates, a formidable predator of prehistoric Australia.  The scientific paper describes new specimens of an extinct crocodylian genus Baru.  One species, Baru wickeni was previously only known from fossil material collected from the famous Riversleigh World Heritage area in Queensland.  However, the paper describes new B. wickeni fossil discoveries from a site approximately twenty-five miles south of Alice Springs in the Northern Territory.  Thus, the known range for Baru wickeni has been extended.

A Reconstruction of the Large Prehistoric Crocodile Baru wickeni

The ancient Australian crocodile Baru wickeni

A life reconstruction of the broad-snouted ancient crocodylian Baru wickeni.

Picture Credit: Paul Willis

In addition, the paper documents the species of another member of the Baru genus – Baru darrowi.  B. darrowi was previously only known from the Bullock Creek site in the Northern Territory, but fossils of this reptile have also been found in the Riversleigh World Heritage area.  Thus, the range of this species has been extended too.

Baru- Formidable Ancient Aussie Croc

Crocodiles assigned to the Baru genus were formidable, large predators equivalent in length to a fully-grown, extant Saltwater crocodile (Crocodylus porosus).  The skull was much more robust, the snout was broader and the head was deeper.  Furthermore, the teeth were proportionately bigger and the jaws were powered by particularly massive muscles.  Today’s “Salties” are extremely dangerous and they do attack large vertebrates including people when the opportunity arises, but mostly these crocodiles, the largest living reptiles, subsist on prey much smaller than themselves such as fish and turtles.

The skull and jaw adaptations of Baru indicate that this crocodylian was specialised towards subsisting on large vertebrate prey (animals of similar size to itself), ambushing its victims close to water sources.  In outward appearance Baru would have resembled a modern crocodile, but the deeper head and alligator-like overbite would have been more pronounced.

The Significance of the Scientific Paper

Author, Adam Yates, (Senior Curator of Earth Sciences at the Museum of Central Australia, part of the Museum and Art Gallery of the Northern Territory), has established that these two species (B. wickeni and B. darrowi) had much wider geographic ranges that in all likelihood encompassed the northern third to half of the continent.  These two species, however, did not compete with each other, as they were separated in geological time.  Baru wickeni lived earlier, its fossils date from the Late Oligocene Epoch (about 25 million years ago).  In contrast, Baru darrowi lived more recently, its remains are associated with Middle Miocene Epoch deposits (approximately 13 million years old).

A Skull of Baru wickeni from the Riversleigh World Heritage Site (Queensland)

B. wickeni skull.

A skull of the prehistoric crocodile Baru wickeni.

Picture Credit: Adam Yates

The picture (above) shows a new skull (dorsal view) of B. wickeni excavated from Riversleigh World Heritage area deposits.  This skull represents the most complete skull of any Baru species described to date, full details can be found in the scientific paper: PeerJ Paper

Helping to Map the Timespan of Australia’s Cenozoic Terrestrial Vertebrate Fossil Sites

The Cenozoic vertebrate fossil assemblages of Australia have proved troublesome to date accurately due to the vast distances evolved between sites and their temporal isolation.  As these species of crocodiles have broad geographical ranges but relatively constrained chronological timespans, these fossils may be helpful when it comes to determining the age of some vertebrate fossil sites in Australia where there is no radiometrically dateable material and no associated mammal fossils that would normally assist with relative dating.

Another interesting implication from this paper is the presence of Baru wickeni from south of Alice Springs in what was then (and still is now) part of the Lake Eyre drainage system.  Previously Baru was known only from coastally draining marginal areas of northern Australia, while rocks of the same age in the Lake Eyre Basin of South Australia produced a distinctly different type of extinct crocodile called Australosuchus.  It was therefore suggested that Australosuchus was a denizen of the internally draining rivers of central Australia while Baru lurked in the northern fringes in rivers that drained to the north coast.  The presence of Baru wickeni south of Alice Springs, in what is part of the Lake Eyre Basin, disproves this hypothesis.  Instead the pattern may be the result of palaeolatitude, and consequently climate, with Australosuchus potentially being more tolerant of cooler conditions and subsequently occupying the cool south and Baru in the warmer northern part of the continent.

The scientific paper: “The biochronology and palaeobiogeography of Baru (Crocodylia: Mekosuchinae) based on new specimens from the Northern Territory and Queensland, Australia” by Adam Yates, published in PeerJ.

Our thanks to Adam Yates and the Museum and Art Gallery Northern Territory for the compilation of this article.

13 06, 2017

Watch the Birdie (Enantiornithine in Amber)

By | June 13th, 2017|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Nearly Complete Baby Bird Preserved in Amber

Researchers from the Chinese Academy of Sciences in collaboration with colleagues from the Royal Saskatchewan Museum (Canada) and the China University of Geosciences have announced the discovery of yet another prehistoric animal preserved entombed within a 99-million-year-old piece of amber from Myanmar.  The animal is a baby bird, perhaps only a few days old when it was engulfed in sticky tree resin back in the Cretaceous.  It is an astonishing discovery, one of a number of remarkable fossil finds made in recent years from the amber deposits of northern Myanmar.  Most of the skull and neck is preserved along with part of a wing, a hindlimb, complete with claws and some soft tissue surrounding the tail.  Some of the plumage has also been encased within the amber nodule.  Described as representing a specimen of the Enantiornithes clade, it is the most complete bird preserved in amber found to date.

Enantiornithine Hatchling Preserved in Burmese Amber

Baby Enantiornithine bird trapped in amber.

Baby bird preserved in amber.

Picture Credit: Ryan McKellar (Royal Saskatchewan Museum) et al.

The picture above shows the amber nodule (a).  The nodule measures approximately 86 mm × 30 mm × 57 mm it has been assigned the specimen number HPG-15-1 and it has been cut in half.  The cut-mark is represented in (c) which shows the cut as a dotted line against a line drawing of the bird’s remains preserved in the nodule.  An interpretation of the high-resolution scans showing the skeletal components is shown in (b).  The disarticulated remains of this individual has led the research team to speculate that the corpse of this young bird might have been scavenged prior to its entombing in the tree resin.

A Very Young Bird

Writing in the academic journal “Gondwana Research”, the scientists conclude that the shape of the skeleton and the plumage indicates a very young bird, the well-developed wings, claws and the presence of some filamentous body feathers suggests that Enantiornithines were hatched in a relatively advanced state, being perhaps able to feed itself almost immediately.  Being born nearly fully developed and independent of the parents is termed precocial.  Many modern birds are precocial, examples include ostrich chicks and ducklings.  These birds are able to keep themselves warm and move about, often leaving the nest in just a few hours.  The scarcity of body feathers on the Cretaceous bird represents a distinct departure from the feather coverings found in today’s precocial birds.  Perhaps the Enantiornithines relied on their parents to brood them to keep them warm, or perhaps these birds hatched during the hottest part of the year, when insulation was not as necessary.

A Three-Dimensional Model Created from the High-Resolution Scans

Fossil bird trapped in amber.

Using 3-D scans the researchers were able to create a model of the death pose of the bird.

Picture Credit: Ryan McKellar (Royal Saskatchewan Museum)

Commenting on the importance of this fossil discovery, Ryan McKellar (Royal Saskatchewan Museum) stated:

“We’ve had more complete specimens, where you get more of the skeleton preserved, from compression fossils, but never with this level of detail.  It’s like a little diorama.”

Nicknamed “Belone”

The amber nodule also contains insect remains, plant material and mites, providing an insight into the fauna and flora of a conifer forest that existed around 99 to 100 million years ago.  The amber was found by a miner back in 2014, at first the claw was thought to have come from a lizard but once the piece had been purchased by the Hupoge Amber Museum in Tengchong City, China, a correct identification was made.  The specimen was nicknamed “Belone” a local term for an amber-coloured bird called the Oriental skylark.

Researchers including palaeontologist Lida Xing (China University of Geosciences), used CT scans to examine fossil elements hidden from view.  These scans revealed the skull and part of the spine, although the cutting of the nodule damaged the anterior portion of the head and the tiny jaws.

As for its feathers, the bird had different kinds: some that palaeontologists have seen on dinosaurs, but others that are closer to modern-day birds.  This, the research team commented, was one of the most surprising and rewarding finds.

The Enantiornithine Hind Leg

Enantiornithine hindlimb

A closer view of the hind limb of the Enantiornithine bird.

Picture Credit: Ming Bai

A Precocial Bird

The presence of strong toes equipped with sharp claws suggests that this bird could clamber around in the trees shortly after hatching, yet more evidence of just how independent this young bird was.  Precociality is thought to be ancestral in birds.  Thus, altricial birds tend to be found in the most derived families within the Aves (birds) Order.   There is some evidence for precociality in the Dinosauria.  It seems that being independent at birth is a characteristic that is basal to the birds.

A Close View of One of the Claws

Enantiornithine claw.

A close view of the claw, even individual scales have been preserved in the amber.

Picture Credit: Ming Bai

The amber mines of Kachin Province (northern Myanmar) are renowned for their remarkable fossils, back in 2016, Everything Dinosaur wrote an article about the remnants of a bird’s wing that had been preserved trapped in amber.

To read more: Bird Wing Trapped In Amber

Later that year, Everything Dinosaur reported on discovery of a fragment of a dinosaur’s tail that had been found preserved inside amber.  That remarkable specimen was studied by a number of the researchers who contributed to the study of this baby bird fossil.

To read more about the dinosaur tail discovery: The Tale of a Dinosaur Tail

The scientific paper: “A mid-Cretaceous Enantiornithine (Aves) Hatchling Preserved in Burmese Amber with Unusual Plumage” by Lida Xing, Jingmai K. O’Connor, Ryan C. McKellar, Luis M. Chiappe, Kuowei Tseng, Gang Li, Ming Bai published in Gondwana Research.

31 05, 2017

Oldest Swinger in Town – Torrejonia wilsoni

By | May 31st, 2017|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles|0 Comments

New Mexico’s Oldest Primate Torrejonia wilsoni

A partial fossilised skeleton of a very ancient ancestor of humans discovered in north-western New Mexico has revealed that the first primates lived in trees and that they were not obligate ground-dwellers.  More complete fossil material shows that the Palaeocene plesiadapiform known as Torrejonia wilsoni was adapted for a life in the trees.  The fossil discovery is important as most of the Palaeocene mammals associated with the first primates (Euprimates) are only known from a handful of bones and isolated teeth.

The Torrejonia wilsoni Fossil Material Indicates an Arboreal Existence

Torrejonia fossil material (T. wilsoni).

A skeleton composite of Torrejonia wilsoni (NMMNH P-54500).

Picture Credit: Royal Society Open Science

The picture shows illustrations of the fossil material of T. wilsoni (specimen number NMMNH P-54500), with the bones and teeth mapped onto a line drawing of the animal.  Scale bar equals 1 cm.

Box a = elements from the skull

Box b = parts of the jaws

Box c = arm bones

Box d = the shoulder blade (scapula- fragmentary)

Box e = elements from the astragalus (ankle)

Box f = leg bones

Getting into the Swing of Things Once the Dinosaurs Had Died Out

It may sound surprising, but one of the first groups of mammals to rapidly diversify and to become more specious after the extinction of the dinosaurs were the Euarchonta (tree shrews, colugos and primates).  These creatures have their origins in the Late Cretaceous and with the extinction of the non-avian dinosaurs, within a few million years, a number of new Euarchonta families had evolved.  The sediments that form the Early Palaeocene Nacimiento Formation (San Juan Basin, New Mexico), are one of the most important lithological units for fossils of these small mammals.

A fragmentary skeleton of the plesiadapiform Torrejonia wilsoni found in Torrejonian-aged deposits (NALMA – North American Land Mammal Ages), dating to around 62 million-years-ago, indicates that this animal had an arboreal existence.  Previously, many researchers had proposed that the plesiadapiforms, an extinct group of primitive placental mammals, close to the ancestry of primates, had been terrestrial creatures.  However, unlike most of the fossils associated with this group of mammals, this specimen of T. wilsoni provided scientists with key insights into the animal’s limbs and joints and a subsequent analysis revealed that it would have been at home in the trees.

Illustrations of Typical Plesiadapiforms

Illustrations of plesiadapiforms.

Illustrations of typical plesiadapiforms Plesiadapis cookei (centre) and Carpolestes simpsoni (top right).

Picture Credit: DMP (Princeton Field Guild to Prehistoric Mammals)

Dr Thomas Williamson (New Mexico Museum of Natural History and Science), one of the authors of the academic paper published today in the on-line journals of the Royal Society Open Science found the fossil material with his twin sons Ryan and Taylor.  Teeth associated with the skeleton allowed the researchers to identify the fossil material as T. wilsoni, no easy task as the skeleton was found jumbled up and mixed in with two other mammals, a partial skeleton of Acmeodon secans and an almost complete skeleton of Mixodectes pungens.

Lead author of the study, Stephen Chester (University of New York) stated:

“This is the oldest partial skeleton of a plesiadapiform and it shows that they undoubtedly lived in trees.  We now have anatomical evidence from the shoulder, elbow, hip, knee and ankle joints that allows us to assess where these animals lived in a way that was impossible when we only had their teeth and jaws”.

In addition, the research team contend that all of the geologically oldest primates known from skeletal remains, encompassing several species, were tree-dwellers.  It seems that the plesiadapiforms, the last of which died out in the Late Eocene, had forward facing eyes and relied more on smell than living primates do.  Analysis of the skeleton of Torrejonia wilsoni places plesiadapiforms as a transitional group between other mammals and the true primates.

19 05, 2017

Say it with Flowers from the Danian to be Exact

By | May 19th, 2017|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Flowering After a Disaster – Oldest Buckthorn Fossilised Flowers

Next week sees the start of the prestigious Chelsea Flower Show.  The great and the good will be attending this Royal Horticultural Society event, regarded by many gardeners and growers as the highlight of the year.  Today, Everything Dinosaur turns its attention to a paper published earlier this month in the journal PLOS ONE.  A team of researchers have found fossils of flowering plants that were once growing in Argentina, not long after, (in geological terms anyway), the global catastrophe that wiped out the non-avian dinosaurs.  The fossils represent plants of the Rhamnaceae family, commonly referred to as Buckthorns.  These plants have a global distribution today and a number of species can be found in parks and gardens in the UK.

Two Fossilised Flowers Identified as Members of the Rhamnaceae Family (Buckthorn)

Two Buckthorn flower fossils.

Two fossilised Buckthorn flowers next to each other were discovered in shales of the Salamanca Formation in Chubut Province, Patagonia, (Argentina).

Picture Credit: Nathan Jud/Cornell University (USA)

Flowering After the Fern Spike

A lot has been written about the mass extinction event that marked the demise of the non-avian Dinosauria, some 66 million years ago.  However, as well as the dinosaurs, pterosaurs and many kinds of marine reptile, other groups of animals (and plants), were devastated in the impact event and its aftermath.  Plant families were decimated too and researchers have been examining strata that were laid down in the years following the end Cretaceous extinction event in a bid to assess how ecosystems recovered.

Micro-fossil studies indicate that it was the ferns that were the first major group of plants to recover after the end Cretaceous mass extinction.  In the Late Cretaceous (Maastrichtian faunal stage), fern spores make up around 10 to 25% of the plant micro-fossil assemblage.  In Danian Epoch deposits, laid down at the very beginning of the Palaeocene, scientists find that in some parts of the world, fossilised fern spores make up nearly 99% of the plant micro-fossil assemblage.  This is referred to as the “Fern Spike”, ferns recovering quicker than angiosperms and other types of plants.  This recovery is echoed today, as ferns are often the first to colonise land devastated by a volcanic eruption.

The “Fern Spike” – Plotted Against Geological Time

Plotting the Danian fern spike.

A graph showing the recovery of ferns after the Cretaceous mass extinction.

Graph Credit: Everything Dinosaur

The research team including lead author Nathan Jud (Cornell University), report on the discovery of the first fossilised flowers post the Cretaceous extinction to be found in South America.  The fossils date to the early Palaeocene (Danian faunal stage), less than one million years after the extraterrestrial impact event.  The flowers and other plant fossils were found in shales which form part of the Salamanca Formation (Chubut Province, Patagonia).

Commenting on the significance of their discovery, Nathan Jud stated:

“The fossilised flowers provide a new window into the earliest Palaeocene communities in South America and they are giving us the opportunity to compare the response to the extinction event on different continents.”

The Origins of the Rhamnaceae Family

Plants of the Rhamnaceae family might have a global distribution today, but from where did this highly successful group of shrubs, trees and bushes originate?  Scientists have argued about whether early Buckthorns originated in the ancient super-continent Gondwana, which later split and includes most of the landmasses in the Southern Hemisphere today.  Or did the Rhamnaceae evolve further north on another super-continent from the Mesozoic – Laurasia?

Dr Jud commented:

“This and a handful of other recently discovered fossils from the Southern Hemisphere, supports a Gondwanan origin for the Rhamnaceae, in spite of the relative scarcity of fossils in the Southern Hemisphere relative to the Northern Hemisphere.”

Fossilised Leaves from the Salamanca Formation (Buckthorn Family)

Views of Buckthorn leaves (Danian faunal stage).

Buckthorn fossils (leaves).

Picture Credit: Nathan Jud/Cornell University and PLOS ONE

The scientists, which include Ari Iglesias (Universidad Nacional del Comahue, Argentina), and Peter Wilf (Pennsylvania State University), suggest that fossils found in southern Mexico and Columbia provide evidence that the first members of the Rhamnaceae family evolved in the Late Cretaceous, shortly before the extinction event.  Although, many types of plant died out at the end of the Mesozoic, the ancestors of extant Buckthorns were able to make it through the global catastrophe.

A plausible scenario is that the Rhamnaceae first evolved in the equatorial region of Gondwana, but survived the extinction event by clinging on in the southern most portion of South America, many thousands of kilometres from the Yucatan peninsula impact site.  These plants were then able to re-colonise other parts of the world in the aftermath of the extinction event, perhaps taking advantage of the niches in ecosystems vacated by recently extinct plant species.

The Salamanca Formation is among the most precisely-dated sites of the Palaeocene. The age of the fossils was corroborated by radiometric dating (using radioactive isotopes), the global palaeomagnetic sequence (signatures of reversals of Earth’s magnetic field found in the samples), along with the mapping of zonal fossils (relative dating).

In conclusion, Dr Jud stated:

“These are the only flowers of Danian age for which we have good age control.  Researchers have discovered other fossilised flowers in India and China from around the Danian, but their dates are not as precise.”

30 04, 2017

DNA from Ancient Hominins Discovered in Cave Sediments

By | April 30th, 2017|Dinosaur and Prehistoric Animal News Stories, Geology, Main Page, Palaeontological articles|0 Comments

DNA from Cave Sediments Reveals Ancient Human Occupants

Close to the Belgium town of Modave, there is a large cave.  It overlooks the Hoyoux River, a tributary of the Meuse and although no human bones have ever been found at this cave site, palaeoanthropologists are confident that it was once occupied by ancient humans as animal bones with stone tool cut marks are associated with the site.  The cave is called Trou Al’Wesse (“Wasp Cave” in Walloon) and thanks to a remarkable application of technology, scientists now know that some fifty thousand years ago, a Neanderthal relieved himself inside the cave.  That person’s urine and faeces may have long since decomposed but, left in the cave sediments were minute traces of his DNA.  Researchers have shown that they can find and identify such genetic traces of ancient humans, enabling them to test for the presence of ancient hominins even at sites where no human bones have been discovered.  In addition, the same technique can be used to map other mammalian fauna at these locations.  The scientists, including researchers from the Max Planck Institute for Evolutionary Anthropology (Leipzig, Germany) propose that this technique could become a standard tool in palaeoarchaeology.

Excavations at the site of El Sidrón, (Spain) – One of the Cave Sites in the Study

Searching for evidence of ancient hominin DNA.

Excavations at the site of El Sidrón, Spain.

Picture Credit: El Sidrón research team

The Secrets of Cave Soils and Sediments

Human remains are extremely rare and although scientists are aware of the existence of ancient hominins such as the Denisovans, they are only known from a handful of fossilised bones (literally, a single finger bone and a possible femur, plus some teeth).  However, cave soils and sediments themselves can provide genetic evidence in the form of tiny traces of ancient hominin DNA.  By examining cave soils and sediments and extracting genetic traces, scientists can gain a better understanding of the evolutionary history of humans, even if no bones or stone tools are present.

The research team members collected eighty-five sediment samples from seven caves in Europe and Russia that humans are known to have entered or even lived in during the Pleistocene Epoch.  The samples dated from between 14,000 and 550,000 years ago.  Using a refined DNA analysis technique, one that was originally designed to identify plant and animal DNA, the team were able to search specifically for hominin genetic evidence.

Commenting on the significance of this research, Matthias Meyer (Max Planck Institute for Evolutionary Anthropology) and co-author of the study published in the journal “Science” stated:

“We know that several components of sediments can bind DNA.  We therefore decided to investigate whether hominin DNA may survive in sediments at archaeological sites known to have been occupied by ancient hominins.”

Entrance to the Archaeological Site of Vindija Cave, Croatia

Searching for traces of ancient human DNA.

Entrance to the archaeological site of Vindija Cave, Croatia.

Picture Credit: Max Planck Institute for Evolutionary Anthropology/J.Krause

The picture above shows a view from the entrance of Vindija Cave in northern Croatia, one of the seven sites studied.  Analysis of microscopic amounts of mitochondrial DNA at the Vindija Cave location confirmed the presence of several large mammals including Cave Bears at this location.  The researchers found evidence of a total of twelve different mammalian families across the sites that were included in this study, including enigmatic, extinct species such as Woolly Mammoth, Woolly Rhinoceros and Cave Hyena.

 Mitochondrial DNA Helps Map the Presence of Large Mammals (Including Hominins)

DNA analysis identifies cave inhabitants.

DNA analysis helps map the presence of mammalian fauna in the absence of body fossils.

Picture Credit: Journal Science

Once animal DNA had been mapped the researchers turned their attention to identifying ancient human genetic traces within the samples.

Lead author of the research paper, PhD student Viviane Slon (Max Planck Institute for Evolutionary Anthropology), explained:

“From the preliminary results, we suspected that in most of our samples, DNA from other mammals was too abundant to detect small traces of human DNA.  We then switched strategies and started targeting specifically DNA fragments of human origin.”

In total, nine samples from four cave sites contained enough ancient hominin DNA to permit further analysis.  Of these, eight sediment samples contained Neanderthal mitochondrial DNA, either from one or multiple individuals, whilst one sample contained evidence of Denisovan DNA.  The majority of these samples were taken from archaeological layers or sites where no Neanderthal bones or teeth had been previously found.

A New, Important Tool for Palaeoanthropology

Svante Pääbo, another co-author of the paper and director of the Evolutionary Genetics department at the Max Planck Institute for Evolutionary Anthropology commented that the ability to retrieve ancient hominin DNA from sediments represented a significant advance in palaeoanthropology and archaeology.  The use of this technique could become a standard analytical procedure in future.

A Sample Ready for Testing

Testing cave sediments for ancient human DNA.

A cave sediment sample is prepared for DNA testing.

Picture Credit: Max Planck Institute for Evolutionary Anthropology/S. Tüpke

Even sediment samples that were stored at room temperature for years still yielded DNA.  Analyses of these and of freshly-excavated sediment samples recovered from archaeological sites where no human remains are found will shed light on these sites’ former occupants and our joint genetic history.

Everything Dinosaur acknowledges the contribution of the Max Planck Institute for Evolutionary Anthropology in the compilation of this article.

23 03, 2017

Root and Branch Reform for the Dinosaur Family Tree

By | March 23rd, 2017|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Dinosaur Family Tree Given a Hefty Shake

So, the scientific paper is out, published in the journal Nature and with the snappy title “A New Hypothesis of Dinosaur Relationships and Early Dinosaur Evolution”.  Just about everything that we thought we knew about when, where and how the dinosaurs evolved has been turned on its head.  In addition, the dinosaur family tree has been re-drawn, all the text books written about these iconic prehistoric animals published since 1887, basically got it wrong!  It’s a big story, it dwarfs Argentinosaurus!  So, let’s take a step back and examine what exactly does this new paper mean.

New Study Suggests Tyrannosaurus rex was put on the Wrong Branch of the Dinosaur Family Tree

"Stan" - Gracile T. rex at Manchester Museum.

Theropods like T. rex re-assigned and united with the bird-hipped dinosaurs in this new model.

We have tried to summarise the key findings as:

  • The clades that make up the Order Dinosauria, need to be rearranged.
  • Theropod dinosaurs which are closely related to modern birds, previously classified as Saurischian dinosaurs (lizard-hipped), need to be grouped with the bird-hipped forms in a new clade proposed as the Ornithoscelida.
  • Bird-hipped dinosaurs (Ornithischia) clade now directly associated with the evolution of birds.
  • Lizard-hipped Sauropodomorpha, the clade that includes Diplodocus, Plateosaurus and Argentinosaurus et al would now fall outside the Order Dinosauria.
  • The definition of what a dinosaur is (Dinosauria) would have to be changed to allow the Sauropodomorpha back in.
  • The first dinosaurs may not have evolved in the southern hemisphere (South America or southern Africa – Gondwana), but they may have evolved further north on the landmass called Laurasia.
  • Under this new redrawing of the dinosaur family tree, some of the Dinosauriforms (ancestors of the Dinosauria), such as Saltopus (fossils from Scotland) and the controversial Agnosphitys (fossils from Avon), provide evidence to support the idea that some of the very first dinosaurs may have evolved in the area we now know as the UK.
  • The first types of dinosaur may have been omnivores and not carnivores as generally accepted.
  • With this re-definition of dinosaur evolution, the first dinosaurs evolved some 247 million years ago, pushing the origins of the Dinosauria back some 15 million years.

The Traditional Dinosaur Family Tree Compared to the New Model

Comparing different views on the dinosaur family tree.

Simplified diagram comparing traditional view of the dinosaur family tree with the new model.

Picture Credit: Everything Dinosaur (from Baron et al 2017)

The picture above shows (top) the traditional view of the dinosaur family tree as proposed by Henry Govier Seeley in a paper entitled “On the Classification of the Fossil Animals Commonly Named Dinosauria” published in the Proceedings of the Royal Society (London) back in 1887.   This has been the accepted, conventional interpretation for the last 130 years or so.

The new model is depicted (bottom), this interpretation reflects in part, the dinosaur family proposed by Thomas Huxley in a paper published in 1870, entitled “On the Classification of the Dinosauria with Observations on the Dinosauria of the Trias” in the quarterly journal of the Geological Society.

Back in 1870, Huxley looked at compsognathids, iguanodontids, Megalosaurs and the primitive armoured dinosaur Scelidosaurus and found enough common characteristics amongst these different types of dinosaur to unite them into a single clade, which he called the Ornithoscelida (orn-nith-oh-skel-lie-dah).  The research team, writing in the academic journal “Nature” had many thousands more fossils to study than either Huxley or Seeley, they conclude that Huxley’s interpretation has more validity than the conventional view that gives precedence to Seeley’s interpretation.  Baron et al suggest that the term Ornithoscelida be resurrected to apply to Ornithischians and the Theropoda.

Hypercarnivory (Meat-eating) Evolved Twice

Everything Dinosaur’s comparison of the two family trees shows something else.  The green lines lead to those groups of dinosaurs that were predominantly herbivorous, whilst the red lines lead to dinosaur types that comprise mainly carnivores.  In the new model, the Sauropodomorpha, dinosaurs like Diplodocus and their kind are placed outside the new definition of the Dinosauria.  The herrerasaurids (Herrerasauridae), with their confusing array of dinosaur and non-dinosaur traits, are also placed outside the new strict definition of what dinosaurs are.  Dinosaurs like Herrerasaurus are not classified as Theropods in this new model, which means that meat-eating in dinosaurs evolved twice, once in the herrerasaurids and once in the Theropoda.

Herrerasaurus Gets a New Status within the Revised Dinosaur Family Tree

An illustration of a Triassic dinosaur Herrerasaurus.

Herrerasaurus Illustration

Science Itself Evolves

At Everything Dinosaur, we define science as “the search for truth”.  The authors of this new paper, graduate student Matthew Baron, Dr David Norman (Cambridge University) and Professor Paul Barrett (London Natural History Museum), reviewed a total of seventy-four different types of dinosaur and looked at their common traits and characteristics.   They started with a blank sheet of paper, bravely set aside conventional thinking and tried to find the best fit for the scientific evidence.

Explaining the researcher’s approach, a spokesperson from Everything Dinosaur commented:

“When you put together a jig-saw puzzle, you might refer to the picture on the front of the box to guide you.  What these scientists did was to look at the jigsaw pieces, ignoring the picture on the front of the box and they worked out which pieces fitted together well and which pieces didn’t.  They took a fresh look at the evidence and came up with a new way of mapping out the dinosaur family tree.  Based on the evidence, they found a better way to put the jigsaw pieces together.”

The researchers carefully studied thousands of fossil bones and mapped 457 anatomical characteristics across the 74 different types of dinosaur.  This meticulous study led them to re-draw the cladogram that represents the dinosaur family tree.

A Phylogenetic Relationship of Early Dinosaurs Plotted Against Geological Time

Re-drawing the dinosaur family tree.

The phylogenetic relationships between early dinosaurs.

The diagram above show the newly proposed phylogenetic relationship plotted against geological time for the early dinosaurs and their close relatives (Dinosauriformes).

A = the least inclusive grouping (clade) that includes the House Sparrow, Triceratops and Diplodocus.
B = the least inclusive grouping (clade) that includes the House Sparrow and Triceratops (the Ornithoscelida).
C = the most inclusive clade that contains Diplodocus but not Triceratops – (the new definition of the Saurischia).

Not “Throwing the Baby Out with the Bathwater”

This is a fascinating and intriguing insight into the phylogenetic relationships of the Dinosauria and their closest relatives.  However, numerous studies have been conducted in the past and Henry Govier Seeley’s analysis has held sway.  Some of the conclusions drawn are likely to be challenged by other palaeontologists and the debate as to the cladistic relationships and the implications for how, when and where the dinosaurs evolved is going to continue.

Take for example, the idea that the dinosaurs may have evolved further north than previously thought.  The fossils from Scotland and the west country of England (Avon) are highly fragmentary and far from complete.  Indeed, much of the Triassic material ascribed to early types of dinosaur or their near relatives, the Silesauridae, is very piecemeal.  Many more fossils need to be found before a clearer picture as to the origins of the Dinosauria can be established.

Footnote

Back in April 27th 2015, Everything Dinosaur published a blog article all about the discovery of a bizarre new Theropod dinosaur named Chilesaurus (C. diegosuarezi).  Although it was classified as a member of the lizard-hipped Theropoda, a group that were predominately meat-eaters, this Late Jurassic, South American dinosaur took a very different evolutionary path – it seems to have become a herbivore.  Chilesaurus, shows anatomical characteristics quite unlike any other Theropod dinosaur.   Not least, the pubis bone is projecting backwards, which is similar in orientation to the layout of the pelvic girdles of Ornithischian (bird-hipped) dinosaurs.  Our article about this very curious dinosaur required us to use an annotated diagram that showed the differences in the hip bones of the Saurischia (lizard-hipped) and the Ornithischia (bird-hipped) dinosaurs.  We are honoured that this same illustration was used by the BBC in the coverage of this new scientific paper.

Classifying the Dinosauria by Their Hip Bones

The shape of the hip bones help to classify the Dinosauria.

Classifying dinosaurs by the shape of their hip bones.

Picture Credit: Everything Dinosaur

The scientific paper: “A New Hypothesis of Dinosaur Relationships and Early Dinosaur Evolution” M. Baron et al published in the journal Nature.

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