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13 08, 2018

Rare Silurian Fossil “Worm” from a Herefordshire Hotspot

By | August 13th, 2018|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

A New Species of Lobopodian from Herefordshire

A team of international researchers including scientists from the Oxford University Natural History Museum, Imperial College London, Manchester and Leicester Universities and the Yale Peabody Museum of Natural History, have identified a new species of lobopodian, a bizarre segmented worm-like creature, in 430 million-year-old rocks in Herefordshire (England).  Digital technology has been utilised to reconstruct a three-dimensional model of this exceptional fossil, an ancient ancestor of the modern, enigmatic Velvet worm.

The Research Team Produced Three-dimensional Images of the Fossil Lobopodian

Thanahita distos - digital reconstruction.

Three-dimensional digital images of the fossil lobopodian from Herefordshire.

Picture Credit: University of Leicester

Soft-bodied, Worm-like Creatures with Legs

Lead author of the study, Derek Siveter, (Professor Emeritus of Earth Sciences at Oxford University and Honorary Research Associate at Oxford University Museum of Natural History), commented:

“Lobopodians are extremely rare in the fossil record, except in the Cambrian Period.  Worm-like creatures with legs, they are an ancestral marine relative of modern-day velvet worms, or onychophorans – predators that live in vegetation, mainly in southern latitudes.”

The Velvet Worm (Peripatus Genus)

Velvet worm - Peripatus.

Peripatus a genus within the  Onychophora – creatures like this may have been the first to walk on land.

Picture Credit: BBC

The Evolution of the Arthropods

Palaeontologists have puzzled for decades over the evolution of groups of modern animals such as the Arthropoda, the largest phylum of animals which includes the trilobites, insects, crustaceans, spiders, scorpions, mites and so forth.  Studies of the exotic Ediacaran and Cambrian biota has helped scientists to better understand the evolutionary relationships between living groups of animals today and their ancient invertebrate ancestors, but many soft-bodied groups are severely underrepresented in the fossil record.  It is still extremely difficult to pin down which type of organism preserved within the remarkable Cambrian-aged Burgess Shale deposits for example, is an ancestor of modern groups of animals alive today.  This newly described fossil specimen, named Thanahita distos represents an example of a member of the Lobopodia, an extremely ancient group of invertebrates that might be a basal member of the Panarthropods – a clade that includes today’s Arthropods, as well as Velvet Worms (Onychophora) and the Water Bears (Tardigrades).

The Silurian-aged deposits in Herefordshire, consist of finely grained volcanic ash layers that settled on a seabed some 430 to 425 million years ago.  These sediments have preserved in exquisite detail many of the marine organisms that roamed across the sea floor.  Writing in the Royal Society Open Science journal, the researchers describe T. distos and note that it is the first lobopodian to be formally described from rocks from the Silurian and it is one of only eight known three-dimensionally preserved lobopodian or onychophoran fossil specimens known to science.

Professor Siveter explained how the team were able to build up a picture of the ancient sea creature:

“We have been able to digitally reconstruct the creature using a technique called physical-optical tomography.  This involves taking images of the fossil at a fraction of a millimetre apart, then “stitching” together the images to form a “virtual fossil” that can be investigated on screen.”

Herefordshire Lagerstätte

The Herefordshire Lagerstätte has provided scientists with numerous exceptionally preserved invertebrate fossils.   Everything Dinosaur has reported on several of these, very significant fossil discoveries on this blog, including one Herefordshire fossil which was named in honour of Sir David Attenborough:

Silurian Fossil Discovery Honours Sir David Attenborough

Professor Siveter outlined how delicate creatures like Thanahita distos became preserved, he stated:

“Thanahita distos and the other animals that became fossilised here likely lived 100 to 200 metres down, possibly below the depth to which much light penetrates.  We deduce this because we found no vestiges of photosynthetic algae, which are common in contemporaneous rocks laid down at shallower points on the seafloor to the east.  Some special circumstances allowed for their remarkable preservation.  The first was the immediate precipitation of clay minerals around the dead organisms, which decayed over time, leaving empty spaces behind.  The mineral calcite – a form of calcium carbonate – then filled these natural moulds, replicating the shape of the animals.  Almost at the same time, hard concretions began to form, being cemented by calcite.  Thanks to the early hardening of these Silurian time capsules in this way, the fossils were not squashed as the ash layer slowly compacted.”

Related to the Enigmatic Hallucigenia

A phylogenetic analysis undertaken by the researchers placed T. distos, together with all the described Hallucigenia species, in a sister-clade to crown-group the Panarthropods.  Its placement in a redefined Hallucigeniidae, an iconic Cambrian clade, indicates the survival of these types of creatures into Silurian times.

The Newly Described Thanahita distos is Placed Within the Enigmatic Hallucigeniidae

An illustration of Hallucigenia.

Scientists have classified the newly described T. distos as a relative of the bizarre Cambrian Hallucigenia from the Burgess Shale of British Columbia.

Picture Credit: Danielle Dufault

The professor added:

“Some lobopodians lie in a position on the tree of life which foreshadows that of the terrestrial velvet worms, while others are precursors of the arthropods: the “king crabs”, spiders, crustaceans and related forms.  Since its discovery, the Herefordshire Lagerstätte has yielded a diversity of arthropods that have contributed much to our understanding of the palaeobiology and early history of this very important invertebrate group.  The lobopodian Thanahita distos belongs to an extended, Panarthropod grouping.”

The discovery of the Herefordshire specimen and its subsequent phylogenetic analysis indicates that the lobopodian group, which is associated with Late Cambrian strata, persisted into the Silurian, thus demonstrating that these creatures survived for at least 100 million years.

A Fossil of Hallucigenia Specimen from the Late Cambrian Rocks of British Columbia

A Hallucigenia specimen (Burgess Shale).

A Hallucigenia specimen (Royal Ontario Museum) from the Late Cambrian deposits of British Columbia.  The red arrow is highlighting a droplet-like structure, once thought to represent the head but now regarded as probable gut contents.

Picture Credit: Royal Ontario Museum/Dr Jean Bernard Caron

The scientific paper: “A Three-dimensionally Preserved Lobopodian from the Herefordshire (Silurian) Lagerstätte, UK” by Derek J. Siveter, Derek E. G. Briggs, David J. Siveter, Mark D. Sutton and David Legg published by the Royal Society Open Science

10 08, 2018

The Really Dangerous Predator of Hell Creek

By | August 10th, 2018|Dinosaur and Prehistoric Animal Drawings, Dinosaur Fans, Everything Dinosaur Products, Main Page, Photos of Everything Dinosaur Products, Photos/Pictures of Fossils|1 Comment

Acheroraptor temertyorum – Most Dangerous Critter of Hell Creek

If you could travel back in time and visit western North America 66 million years ago, you might find yourself within the territory of a Tyrannosaurus rex.  Not a very safe place to be you might think, you would probably be right, but the Hell Creek fauna contained another Theropod dinosaur, one that was perhaps, more dangerous to a human visitor than a T. rex or for that matter the other apex predator known from the Hell Creek Formation – Dakotaraptor steini.

Named and scientifically described in 2013, the real man-eater of Hell Creek might have been Acheroraptor (A. temertyorum), at around three metres long and weighing as much as a German Shepherd dog, a pack of these ferocious hunters would probably have made short work of any human visitor to the Late Cretaceous who was unfortunate to encounter them.

A Scale Drawing of the Velociraptorine Dromaeosaurid Acheroraptor temertyorum

Acheroraptor temertyorum scale drawing.

A scale drawing of Acheroraptor.

Picture Credit: Everything Dinosaur

“Underworld Plunderer”

Named after the River of Pain “Acheron” in the underworld from Greek myth, Acheroraptor was one of the very last of the non-avian Theropod dinosaurs and it probably played a secondary predator role in the Hell Creek ecosystem.  There were larger predators, the five-and-a-half-metre-long Dakotaraptor for example, that like Acheroraptor was one of the very last dromaeosaurids to evolve.  However, packs of Dakotaraptors and the iconic Tyrannosaurus rex may not have considered a single person much of meal and may not have expanded a lot of energy in trying to catch them.  To a pack of Acheroraptors, a human would have made a very satisfactory lunch, best to avoid Acheroraptor if you can.

To read more about the discovery of Dakotaraptor steiniDakotaraptor – A Giant Raptor

Some of the Typical Dinosaurian Fauna of the Hell Creek Formation (Maastrichtian Faunal Stage of the Late Cretaceous)

Dinosaurs of the Hell Creek Formation.

Typical dinosaurs of the Hell Creek Formation.   Although there were larger predators, to a person visiting Montana 66 million years ago, meeting a pack of Acheroraptors would have been extremely dangerous.

Picture Credit: Everything Dinosaur

Part of the Vertebrate Fossil Collection at the Royal Ontario Museum

The specific or trivial name “temertyorum” was selected to honour James and Louise Temerty in recognition for their outstanding support and contribution to the Royal Ontario Museum, which houses the jaw fragments that led to the scientific description of this dinosaur back in 2013.  Acheroraptor probably lived in packs and may have had a role similar to extant hyenas or jackals in present-day ecosystems.  Palaeontologists had suspected that dromaeosaurids roamed Montana in very last years of the Cretaceous, numerous teeth with their diagnostic wide ridges (denticles) had been discovered, but the lack of fossilised bones prevented scientists from assigning a genus.

The Holotype Fossil Maxilla and Lower Jaw (Dentary) of Acheroraptor

The fossilised jawbones of Acheroraptor.

The jaws of Acheroraptor.

Picture Credit: Royal Ontario Museum

Acheroraptor More Closely Related to Asian Dromaeosaurids

Palaeontologists have concluded that Acheroraptor was more closely related to Asian dromaeosaurids such as Velociraptor (V. mongoliensis), than it was to other North American dromaeosaurids.  Assigned to the Velociraptorinae subfamily of the Dromaeosauridae, the relatively long-snouted Acheroraptor provides supporting evidence to suggest the presence of a Late Cretaceous land bridge between Asia and North America.

A spokesperson from Everything Dinosaur explained:

“There is a considerable amount of evidence that supports the idea of the existence of a Cretaceous Beringian land bridge linking North America and Asia.  This land bridge may not have been permanent but appeared at times when sea levels fell, permitting a faunal exchange between dinosaur-based ecosystems.  The ancestors of Acheroraptor temertyorum probably migrated into North America.”

To read Everything Dinosaur’s recent article about Alaskan trace fossils providing evidence of a mixing of dinosaur faunas from Asia and North America: Did Alaskan Therizinosaurs and Hadrosaurs Live Together?

Beasts of the Mesozoic 1/6th Scale Acheroraptor temertyorum

There are lots of models of the Hell Creek Formation biota available, countless T. rex and Triceratops figures for instance, but it was the clever and talented David Silva of Creative Beast Studio who created a 1/6th scale replica of Acheroraptor within the amazing “Beasts of the Mesozoic” model range.

The “Beasts of the Mesozoic” Acheroraptor temertyorum Figure

Beasts of the Mesozoic Acheroraptor temertyorum figure.

The Beasts of the Mesozoic Acheroraptor model.

To view the beautiful Acheroraptor model and the rest of the figures in the “Beasts of the Mesozoic Raptor” range: Beasts of the Mesozoic “Raptors”

6 08, 2018

What Did the Long-necked Plesiosaurs Use Their Necks For?

By | August 6th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Photos/Pictures of Fossils|0 Comments

Nichollssaura borealis – Shaking its Neck from Side to Side

The long-necked Plesiosaurs (Plesiosauroidea), are characterised (unsurprisingly), by their long necks, which in the case of the elasmosaurids were taken to extremes with some Late Cretaceous species having necks around seven metres in length, comprising 76 cervical vertebrae, but how did these marine reptiles use their necks?  What degree of movement did these long necks have?  These are questions that have been debated by palaeontologists for nearly two hundred years.

New research, published this week by the Royal Society, sheds light on the flexibility and neck movement in one Plesiosaur, the Early Cretaceous leptocleidid Nichollssaura borealis.

The Fossilised Skeleton of Nichollssaura borealis (TMP 1994.122.0001)

Nichollssaura borealis type specimen.

Superbly preserved Plesiosaurus fossil – the type specimen of Nichollssaura borealis in dorsal view.

Picture Credit: Everything Dinosaur/Royal Tyrrell Museum (Drumheller))

Defining the Plesiosauria Clade

The Plesiosauria clade was very successful, originating in the Triassic and persisting until the very end of the Cretaceous.  This clade is split into three distinct groups, although palaeontologists debate the phylogeny between the Plesiosauria clade members.

  1. The Plesiosauroidea – the long-necked marine reptiles, epitomised by short tails, broad bodies, four flippers, a small head and an elongated neck.
  2. The Pliosauridae – the short-necked Plesiosaurs, with large heads, broad bodies, four flippers and much shorter necks than the Plesiosauroidea.
  3. The Rhomaleosauridae – a sort of half-way house between the other two, typically possessing longer necks and smaller heads relative to the Pliosauridae, but have shorter necks and larger heads when compared to members of the Plesiosauridae.  Most known rhomaleosaurids are confined to the Early to Middle Jurassic of Europe, with most specimens assigned to this group having been found in England.

The Three Groups Within the Plesiosauria

The Plesiosauroidea illustrated

The three groups that make up the Plesiosauroidea.  The long-necked Plesiosauroidea, the short-necked Pliosauridae and the Rhomaleosauridae.

Picture Credit: Everything Dinosaur

Studying One Member of the Plesiosauroidea – Nichollssaura borealis

The researchers from the Royal Tyrrell Museum and the University of Calgary, focused their study upon one specimen, a member of the Plesiosauroidea called Nichollssaura borealis.  This specimen was chosen as it represents a very nearly complete individual and the fossil is not distorted or crushed to any degree which might have comprised any research into neck flexibility.  There were two further, more practical reasons why N. borealis was selected.  Firstly, the specimen is housed at the Royal Tyrrell Museum and since one of the researchers involved in the study was Donald Henderson, a curator at the museum, accessing the specimen was not a problem.  In addition, with a total length of 2.6 metres Nichollssaura could squeeze into the medical CT scanner that was being used to create accurate three-dimensional images of the bones.

Once the specimen had been CT scanned, the subsequent three-dimensional models that were produced could be examined so as to conclude the range of movement afforded by the 24 bones in the neck of this Plesiosaur (24 cervical vertebrae).

The Research Team Tested the Range of Neck Movement Using Three-Dimensional Models

The range of neck movement in Examining the range of motion of Nichollssaura borealis.

Examining the range of motion of Nichollssaura.

Picture Credit: Royal Society Open Science

Sideways Movement of the Neck

When the three dimensional models of the Nichollssaura borealis neck were examined the scientists discovered that the neck of this Plesiosaur was indeed very mobile, but their results suggest a preference for lateral (sideways) movements of the neck in this species.  This supports the idea that these marine reptiles fed in or along the seafloor, using their small heads and long necks to probe into the sediment to find invertebrates and fish.  Unfortunately, no gut contents indicating potential prey have been preserved in association with the single fossil specimen of Nichollssaura, however, other researchers have found prey gut contents in other plesiosaurids that supports the idea that these animals fed by disturbing and catching animals that live on the sea floor (epifaunal).

To test the validity of the three-dimensional computer models, the scientists studied the range of neck movement in a extant species of monitor lizard, Dumeril’s monitor, a species from south-east Asia (Varanus dumerilii).  This species was chosen as it has a relatively long neck for a monitor lizard and a preserved specimen was available for study.

The researchers conclude that if this species of plesiosaurid (N. borealis) had a neck that was adapted to rapid sideways movements then this probably evolved in relation to feeding method and prey capture.  Different types of Plesiosauroidea with their different neck lengths very likely had different ecological roles within the ecosystem.  This study also demonstrates that three-dimensional modelling is an effective tool for assessing function morphology for structures where no good, living analogue for comparison exists.

5 08, 2018

Dorset Dinosaur Tracks Discovered

By | August 5th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Photos/Pictures of Fossils|0 Comments

Sauropod Trackways Discovered in Dorset

Scientists have been measuring and mapping a set of dinosaur tracks found in a quarry in Dorset.  The saucer-shaped tracks were made by a herd of long-necked Sauropod dinosaurs that crossed a stretch of a tidal lagoon back in the Early Cretaceous.  The quarry is located close to the village of Worth Matravers, around three-and-a half-miles east of the coastal town of Swanage, on the Isle of Purbeck.

A View (Dorsal) of a Dinosaur Footprint (Sauropoda)

Sauropod fossil footprint (Dorset).

Dorsal view of one of the dinosaur footprints (Sauropoda).

Picture Credit: Bournemouth University

Giant Dinosaur Footprints

The group of large dinosaurs were walking slowly in a herd, leaving a series of parallel trackways.  They have been described as “giant saucer-shaped depressions just a few millimetres deep”, according to geologist Matthew Bennett from Bournemouth University who has been called in to study and map the fossilised tracks.

The quarry is the property of Lewis Quarries, one of a number in the area that provide valuable limestone blocks for the construction industry.

An Aerial View of the Dinosaur Tracks

Dorset Dinosaur Footprint Quarry Site (Sauropoda).

An aerial view of the Dorset dinosaur footprint site.

Picture Credit: Bournemouth University

The footprints were made between 139 and 145 million years ago (Early Cretaceous), the tracks were infilled by lime rich muds, creating trace fossils.

David Moodie, a spokesperson for Lewis Quarries explained:

“It became apparent that we had come across something of historical interest, so working closely with the National Trust and Professor Matthew Bennett of Bournemouth University, we were able to move forward in the best way without stopping progress in the quarry itself.”

National Trust Lead Ranger Jonathan Kershaw added:

“The group of dinosaurs that made these tracks may be the same ones whose footprints can still be seen in situ just nearby at Keates Quarry just off the Priest’s Way bridleway.  It’s exciting to think that giant Sauropods once roamed where today there are dry stone walls, skylarks and nesting seabirds.”

An Illustration of the Sauropods Crossing the Shallow Lagoon

Sauropod illustration.

Sauropod illustration – Sauropods crossing a shallow lagoon.

Picture Credit: Bournemouth University

In 2015, Everything Dinosaur reported on the discovery of a series of Sauropod footprints and tracks on the Isle of Skye.  These tracks were made in similar circumstances as the Purbeck limestone prints, a group of Sauropods crossed a shallow lagoon, however, the Isle of Skye prints are around thirty million years older and date from the Middle Jurassic.

To read more about the Sauropod prints from the Isle of Skye: Isle of Skye Sauropods and their Watery World

DigTrace Maps the Fossil Footprints

Using a process of photogrammetry and special freeware developed at Bournemouth University called DigTrace, Professor Bennett carefully documented the tracks in three dimensions.  The DigTrace technology was developed with a government grant and help from the Home Office and National Crime Agency.  Its principle aim is to forensically examine footprints and other tracks related to crime scenes, however, it is ideal for plotting the movements of extinct dinosaurs too.

Professor Bennett commented:

“This technology is now being used by the police to help track criminals via their footprints, but we can also use it to record and preserve rare footprints like these.  The beauty of capturing the tracks in 3D is that they can be analysed digitally and even printed in the future, no need to hold up the quarrying for long.”

Drawing Up a Conservation Plan for the Dinosaur Tracks

With the co-operation of Lewis Quarries and in collaboration with the National Trust and researchers at Bournemouth University, a conservation plan is being prepared.  It is hoped that the tracks will be lifted from their setting and put on public display once all the appropriate scientific steps (pardon the pun), have been taken.

The trackway surface is also exposed in nearby Keates Quarry where the National Trust maintains a small conservation area of similar tracks.

Professor Bennett concluded:

“What is remarkable, is that the tracks at both adjacent quarries were probably made by the same animals moving along the coast.  The dip of the beds, folded when the European Alps were pushed up, means that the tracks are closer to the ground in Keates Quarry and can be preserved but are much deeper at Lewis Quarries where in situ preservation is not possible.”

The Dig Site at the Dorset Quarry

The Dorset Sauropod dinosaur trackway.

The Sauropod trackway site (Purbeck limestone).

Picture Credit: Everything Dinosaur

Everything Dinosaur acknowledges the assistance of the media centre at Bournemouth University for the compilation of this article.

1 08, 2018

How Did We Get Our Bones?

By | August 1st, 2018|Dinosaur and Prehistoric Animal News Stories, Main Page, Photos/Pictures of Fossils|0 Comments

Tracing the Origins of the Vertebrate Skeleton

Our skeleton is very special, the evolution of a rigid internal skeleton (bones), was an extremely significant development in the history of life on Earth.  However, how hard, internal skeletons evolved has been the subject of much debate amongst palaeontologists.  However, thanks to research undertaken by scientists at Manchester and Bristol Universities in collaboration with the technicians at a synchrotron light source based in Switzerland, we might have a better understanding of how we came to be.

All living vertebrates have skeletons built from four different tissue types: bone and cartilage (the main tissues that human skeletons are made from), and dentine and enamel (the tissues from which our teeth are constructed).  These tissues are unique because they become mineralised as they develop, giving the skeleton strength and rigidity.

Primitive fish were the first to develop a mineralised skeleton and one group of early fishes, the Heterostracans, has attracted a lot of interest from scientists as they try to work out the evolutionary processes that took place.  The Heterostracans, were a group of heavily armoured, jawless fishes that evolved during the Early Silurian.  These fish, which are mostly associated with marine and estuarine deposits, had two plates, one on the top of the body and one underneath, they served to help protect the animal from attack and might have had a secondary function to help keep the body stiffened.  These fish also had large scales on their bodies too.

A “Swimming Table Tennis Paddle” –  A Life Restoration of Drepanaspis – An Early Devonian Heterostracan

Drepanaspis life reconstruction.

A life reconstruction of Drepanaspis a typical Heterostracan fish.

Picture Credit: Everything Dinosaur

The Primitive Bone-like Tissue Aspidin

Earlier research had identified that the surface scales and broad plates of these primitive fishes had enamel-like tops over a core of dentine, essentially the same material that forms our teeth.  Supporting these structures was a layer of sponge-like material called aspidin.  Aspidin is bone in its earliest mineralised form.  It is thought that the very first basal, internal skeleton provided an anchor to support the armour that was on the outside of the body.  In this new study, the scientists used synchrotron X-ray tomographic microscopy to reveal the nature of aspidin.

Lead author of the paper, published in the journal “Nature Ecology & Evolution”, Dr Joseph Keating (Manchester University), explained:

“Heterostracan skeletons are made of a really strange tissue called “aspidin”.  It is crisscrossed by tiny tubes and does not closely resemble any of the tissues found in vertebrates today.  For 160 years, scientists have wondered if aspidin is a transitional stage in the evolution of mineralised tissues.”

Errivaspis – A Member of the Heterostraci from the Early Devonian

Errivaspis - primitive fish.

Errivaspis – anterior portion of fossil, from the Early Devonian.

Picture Credit: Keating et al

Ruling Out Other Theories

Scientists had been aware of the spongy nature of aspidin.  However, they were unable to work out what might have filled the pores and spaces in the material, using traditional methods of study.  Knowing what filled these unmineralised spaces would provide the information needed to help demonstrate the role that aspidin played in the evolution of back-boned animals.

Four theories regarding what filled these spaces had been put forward:

  1. The spaces housed cells, like the osteoblasts and osteocytes that are found in living bones.
  2. The spaces were filled with fibres made from proteins such as collagen.
  3. The spaces were filled with dentine.
  4. The spaces were filled with a mixture of dentine and bone.

The team showed that these “gaps” in the aspidin represented the location of bundles of collagen (2).  These “gaps” housed the same sort of protein that is found in our skin and bones (in fact collagen is the most abundant type of protein found in our bodies).

These findings enabled Dr Keating to rule out all but one theory for the tissue’s identity, proving that aspidin is the earliest evidence of bone in the fossil record.

Co-author of the study, Professor Phil Donoghue (University of Bristol), who has done much to reveal the true anatomical nature of the Heterostracans, stated:

“These findings change our view on the evolution of the skeleton.  Aspidin was once thought to be the precursor of vertebrate mineralised tissues.  We show that it is, in fact, a type of bone, and that all these tissues must have evolved millions of years earlier.”

The team suggest that the collagen bundles form a scaffold which permits minerals to be deposited.  Aspidin is acellular dermal bone, so one question is answered but it gives rise to a host of others.  For example, if all the skeletal tissue types associated with vertebrates were present in the Heterostracans, then these structures and materials must have evolved earlier than expected.

The scientific paper: “The Nature of Aspidin and the Evolutionary Origin of Bone” by J. Keating, C. Marquart and P. Donoghue published in Nature Ecology & Evolution.

24 07, 2018

Lingwulong New Dinosaur Discovery from Northern China

By | July 24th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Lingwulong shenqi – The Dinosaur That’s Not Supposed to be There

Dinosaurs, so often regarded in the past as epitomising animals that were too slow and stupid to survive, are demonstrating that they were one of the most successful groups of terrestrial vertebrates to have evolved.  A newly described, long-necked dinosaur from the Middle Jurassic of northern China suggests that Sauropods dispersed and diversified much earlier than palaeontologists had previously thought.  The new dinosaur has been named Lingwulong shenqi and it is the earliest known diplodocoid.

A Life Reconstruction of the Newly Described Lingwulong shenqi

Lingwulong shenqi illustrated.

A life reconstruction of Lingwulong shenqi, the earliest known diplodocoid.

Picture Credit: Zhang Zongda

Subgroups of Sauropods with Restricted Geographical Ranges

Although the Sauropods dominated terrestrial faunas for much of the Mesozoic and their fossils are globally distributed, scientists had been aware that several subgroups demonstrated restricted geographical ranges.  For example, the Sauropod superfamily Diplodocoidea, which is part of a huge clade of long-necked dinosaurs called the Neosauropoda, was believed to have never existed in eastern Asia.  This permitted a unique range of long-necked dinosaurs to evolve and thrive in this part of the world, the Mamenchisauridae.  In essence, the isolation of eastern Asia permitted to evolution of the region’s very own endemic range of dinosaurs.

The Neosauropoda consists of two distinct groups of Sauropod, firstly there is the Diplodocoidea, this includes some of the most famous dinosaurs of all, animals such as Brontosaurus, Apatosaurus, Diplodocus and Amargasaurus.  The second type of Sauropod within the Neosauropoda are the Macronaria, which consists of equally famous dinosaurs such as Brachiosaurus and Camarasaurus.  It had been thought that once eastern Asia became isolated, the Neosauropods were unable to spread to this part of the world.

Their absence had been explained by the break-up of the super-continent Pangaea.  A seaway was formed cutting off and isolating this part of Asia during the Jurassic.  In the case of the Diplodocoidea, these types of long-necked dinosaur evolved and dispersed but they never reached northern China.  By the time sea levels had changed and land connections were once again formed linking northern China to other land masses in the Early Cretaceous, the diplodocoids were in decline and their numbers and geographic range had been greatly reduced since their Late Jurassic heyday.

The discovery of Lingwulong shenqi changes all this.  Diplodocoids were present in eastern Asia, so they must have evolved and diversified into this region earlier than previously thought, or land bridges may have existed linking this part of Asia to the rest of Pangaea for longer.

Mapping the Distribution of the Diplodocoidea

Mapping Diplodocoidea distribution.

An epicontinental sea formed during the Jurassic which isolated northern Asia from Europe. This restricted the spread of certain types of dinosaur. Diplodocoid dinosaurs had already evolved and spread before northern Asia was cut off.

Picture Credit: Nature Communications with additional annotation by Everything Dinosaur

Co-author of the open access paper published in “Nature Communications”, Dr Philip Mannion (Imperial College London), explained the significance of this dinosaur discovery:

“Not only is it [Lingwulong] the oldest member [of the Diplodocoidea], but it’s the first ever from Asia.  For a long time it was thought that Neosauropods didn’t get into Asia during the Jurassic.  This suggests that firstly [Neosauropods] got in before any kind of barrier came up, but increasingly the geological evidence suggests maybe this barrier was quite ephemeral”

The Formation of the Russian Platform Sea and the Turgai Sea

Tectonic forces led to the formation of an epicontinental seaway during the Middle to Late Jurassic and this isolated northern Asia from the rest of Pangaea.  The fossils of Lingwulong come from the Yanan Formation in the Ningxia Hui Autonomous Region of China, the strata are estimated to be around 175 to 168 million years old (late Toarcian to Bajocian faunal stages).  The discovery of Lingwulong indicates that many advanced kinds of Sauropod originated at least 15 million years earlier than previously realised.  The Diplodocoidea achieved a global distribution whilst Pangaea was still a single, coherent landmass.

A Reconstruction of the Skeleton of L. shenqi and Examples of Some of the Fossil Bones

Skeleton reconstruction and some fossil bones of Lingwulong.

A skeletal reconstruction of Lingwulong shenqi and examples of fossil bones.  In the skeleton drawing, the bones in white represent fossils associated with this taxon.

Picture Credit: Nature Communications

“Lingwu’s Amazing Dragon”

The dinosaur has been named after Lingwu, the region in which the fossils were found and the Mandarin Chinese “long” which means dragon.  The trivial name – shenqi, comes from the Mandarin for “amazing”, reflecting the unexpected discovery of this type of dinosaur in the Middle Jurassic of China.  Excavations originally commenced in 2005 led to the discovery of between 7 and 10 individuals, including two specimens with associated skull material.  The fossils represent a range of animal sizes, representing juveniles as well as adults.  With so much fossil material to study, the researchers were able to assign this new genus to a specific place within the broad Superfamily of the Diplodocoidea.  They conclude that Lingwulong is a basal member of the Dicraeosauridae.

The Dicraeosauridae includes species such as Suuwassea from the Late Jurassic of Montana, Brachytrachelopan from the Late Jurassic of Argentina and Amargasaurus from the Early Cretaceous of Argentina.

The Position of Lingwulong shenqi Within the Neosauropoda

The taxonomic position of Lingwulong.

Plotting the taxonomic position of Lingwulong within the Diplodocoidea.

Picture Credit: Nature Communications

The Bigger Picture

The idea that the eastern parts of Asia were cut off from other landmasses during the Jurassic has been put forward to explain the substantial differences between the Jurassic (and sometimes Early Cretaceous), terrestrial biotas between this part of the world and the rest of Pangaea.  It is likely that a seaway formed to the west of the Ural Mountains (the Russian Platform Sea), this seaway in conjunction with an ingress of water from the north (the Turgai Sea), isolated the land to the northeast.

This isolation has been used to explain the evolution of a number of new types of prehistoric animal  in eastern Asia, such as:

  • Mamenchisaurid Sauropods
  • Oviraptorosaurs
  • Therizinosaurs
  • Marginocephalians

In addition, this sea barrier has been used to explain the absence of many groups that were present elsewhere in Pangaea during the Jurassic, such as:

  • Diplodocoid Sauropods (now debunked by Lingwulong)
  • Early Titanosauriform Sauropods
  • Dromaeosaurids
  • Nodosaurids
  • The lineage leading to the Iguanodontian Ornithopods

The scientific paper: “A New Middle Jurassic Diplodocoid Suggests an Earlier Dispersal and Diversification of Sauropod Dinosaurs” by Xing Xu, Paul Upchurch, Philip D. Mannion, Paul M. Barrett, Omar R. Regalado-Fernandez, Jinyou Mo, Jinfu Ma and Hongan Liu, published in Nature Communications.

21 07, 2018

Akainacephalus johnsoni – Beauty is in the Eye of the Beholder

By | July 21st, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Photos/Pictures of Fossils|0 Comments

Akainacephalus johnsoni – One of the Oldest “Swingers” from North America

On Thursday of last week, a scientific paper was published in the on-line open access journal PeerJ, that described the discovery of a new species of armoured dinosaur from Utah.  The armoured dinosaur was named Akainacephalus johnsoni, the genus name is derived from the Greek meaning “spiky” or “thorn”, a reference to the large number of bony scales (caputegulae) located on the top and sides of the skull.  The species name honours Randy Johnson, a volunteer preparator at the Natural History Museum of Utah, who skilfully and patiently prepared the skull and lower jaws of this newly described Ornithischian.

A Close-up View of the Bony and Scaly Head of Akainacephalus

Akainacephalus johnsoni illustrated.

A close up of the ornate head of Akainacephalus.

Picture Credit: Andrey Atuchin (Denver Museum of Nature and Science)

Secondary Functions of the Dermal Armour

This was one very heavily armoured ankylosaurid, with a face described by many media outlets as “ugly” or being one that only a “mother could love”.  The fossilised skull, which is nearly complete reveals an extensive amount of armour and ornamentation.  For example, the snout is particularly bony, covered in large osteoderms and above each eye there is a substantial horn.  Although this armour would have served as protection against attack, the degree of ornamentation in Akainacephalus was quite remarkable, it is likely that these osteoderms, the various lumps and bumps on the dinosaur’s body and head, served a number of functions.

Suggested functions for the extensive ornamentation of A. johnsoni

  • Anti-glare and anti-dazzle for the eyes.  If you look at the close-up view of the head of Akainacephalus in the illustration (above), the eye is shaded.  The various projections along the broad snout could have obscured the animal’s vision, but the eye would have been shaded from direct sunlight, a positive advantage in the Late Cretaceous of Utah.
  • Sexual selection – the greater the ornamentation the more imposing the individual.  Just as with peacocks and their impressive tails, deer and their antlers, the greater the number of bumps and lumps could have been a sign of the animal’s fitness to mate.  It might be one very ugly looking dinosaur to us, but beauty is in the eye of the beholder, the lumpier the Akainacephalus the greater the appeal of that individual.
  • In a similar vein to the point made above, the ornamentation could have played a role in display, intimidating rivals as part of ritualistic intraspecific combat or helping to put off the unwanted attentions of any large Theropod that had decided to try and make a meal of this four-metre-long armoured dinosaur.
  • Thermoregulation – the dermal armour of crocodilians serves a number of functions, one of which is to help to regulate the animal’s body temperature.  The wide gut of ankylosaurids gave them a large surface area for the sun to beat down onto.  By pumping blood into the osteoderms the animal could cool down, helping to maintain its body temperature.

The Fossil Remains of Akainacephalus and two Skeletal Reconstructions

Akainacephalus fossils and a skeletal reconstruction.

The skeletal remains of Akainacephalus with two line drawings (dorsal and lateral views). Known fossil bones are highlighted in orange.

Picture Credit: PeerJ

Armoured Dinosaur Mixed Up with Lots of Other Fossils

The first fossils were found in 2008, in a quarry which contained a mixed assemblage of vertebrate remains.  Finds at the site, known as the Horse Mountain Gryposaur quarry, include a nearly complete skull of the hadrosaurid Gryposaurus, turtle fossil remains (Arvinachelys goldeni), a skull and postcranial remains of a new taxon of alligatoroid and a poorly preserved partial skull of a small Theropod.

Akainacephalus Wanders Past Ancient Crocodilians

Akainacephalus johnsoni.

The Akainacephalus drawing shows some of the fauna associated with the dig site – crocodiles and a small freshwater turtle (right) – Arvinachelys goldeni.

Picture Credit: Andrey Atuchin (Denver Museum of Nature and Science)

The Amazing Kaiparowits Formation

The fossils were excavated from sediments associated with the Kaiparowits Formation, which provides a unique perspective on the biota of south/central Laramidia during the Campanian faunal stage of the Late Cretaceous.  This thick succession of sandstones and mudstones was deposited at an unusually rapid rate within a time frame of less than two million years, making it one of the most rapidly deposited terrestrial formations in the world.  Akainacephalus dates from 76.2 to 75.9 million years ago, as such it is one of the oldest ankylosaurids known from North America.  It is also the first documented example of ankylosaurid skull and postcranial bones from the Kaiparowits Formation.  Although, some of the fossil bones are in a better condition than others, the fossils, including that amazing tail club are remarkably complete.

Views of the Caudal Vertebrae and the Tail Club of A. johnsoni

Akainacephalus tail club and caudal bones.

Akainacephalus caudal bones and tail club.

Picture Credit: PeerJ

Dinosaur Immigrants from Asia

Those lumps and bumps on the skull (cranial ornamentation), are reminiscent of an armoured dinosaur from New Mexico (Nodocephalosaurus kirtlandensis), the researchers postulate that these dinosaurs might be closely related.  However, it is worth noting that Nodocephalosaurus is around three million years younger than Akainacephalus.  Both Nodocephalosaurus and Akainacephalus are also similar to Asian ankylosaurids such as Saichania chulsanensis, Pinacosaurus grangeri, and the spectacularly horned Minotaurasaurus ramachandrani.   The discovery of Akainacephalus adds support to the idea that ankylosaurids migrated across an ancient land bridge from Asia into North America prior to 76 million years ago.

The addition of this new ankylosaurid taxon from southern Utah provides further information on ankylosaurid diversity and supports the theory regarding there being regional variations in dinosaur biota across Laramidia during the later stages of the Cretaceous.

Indicating that Ankylosaurids Migrated from Asia into North America (Akainacephalus johnsoni)

Akainacephalus johnsoni illustrated.

Akainacephalus illustrated.

Picture Credit: Andrey Atuchin (Denver Museum of Nature and Science)

20 07, 2018

Xiaophis myanmarensis – Dawn Snake of Myanmar

By | July 20th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Photos/Pictures of Fossils|0 Comments

Baby Snake Preserved in Amber from Myanmar

A team of international researchers including scientists from the University of Alberta, Midwestern University and the Chinese Academy of Sciences have published a paper describing the remarkable discovery of the preserved remains of a baby snake entombed in amber from Myanmar (Burma).  Amber deposits from northern Myanmar are providing scientists with some amazing insights into life in a forest some 100 million years or so ago.  Other amber nodules, known as burmite have revealed the preserved remains of baby birds, a dinosaur tail, frogs and an astonishing range of invertebrates and plant material.  The amber is proving to be a treasure trove for palaeontologists helping them to map the biota of a Cretaceous environment.

The Polished Amber Nodule Revealing the Fossilised Remains of a Baby Snake

The fossilised remains of a baby snake preserved in amber

The preserved remains of a baby snake preserved in amber from Myanmar.

Picture Credit: Ming Bai (Chinese Academy of Sciences)

Xiaophis myanmarensis – Dawn Snake of Myanmar

The baby snake measures around eight centimetres in length.  The fossil reveals that the vertebrae are not yet fully formed and this indicates that the snake was very young when it got trapped in the sticky tree resin.  The snake has been named  Xiaophis myanmarensis, which means “dawn snake of Myanmar”.

The international research team, led by Dr Lida Xing (China University of Geosciences, Beijing and the Chinese Academy of Sciences) and Professor Mike Caldwell (University of Alberta), have described this discovery as a remarkable fossil find.

A Life Restoration of Xiaophis myanmarensis

Dawn snake of Myanmar (Xiaophis myanmarensis)

An illustration of Xiaophis myanmarensis (dawn snake of Myanmar).

Picture Credit: Cheung Chung Tat

Not One Fossil Snake but Two

Although the baby snake is missing its skull, ninety-seven vertebrae have been preserved along with associated fossil ribs.  The tiny reptile’s bones were analysed using a synchrotron to bombard the specimen with X-rays and plot the result.  The back bone is remarkably similar to those found in neonatal snakes today.  This suggests that the vertebrae of snakes have remained largely unchanged for 100 million years.

A second amber fossil was discovered, which preserves a piece of the shed skin of another, much larger snake.  It is unclear whether these two fossils represent the juvenile and adult of the same species.

The Skeleton of the Baby Snake As Modelled from the Synchrotron Data

The preserved skeleton of the baby snake Xiaophis myanmarensis.

The skeleton of the baby snake Xiaophis myanmarensis.

Picture Credit: Ming Bai (Chinese Academy of Sciences)

The discovery of this remarkable fossil, along with the piece of shed snake skin helps palaeontologists to build a picture of the evolution of snakes and how they spread following the break-up of the super-continents during the latter stages of the Mesozoic.

Dr Palci (Flinders University) and a co-author of the scientific paper published in the journal “Science Advances” commented:

“At 100 million years old, it dates back to the age of the dinosaurs, well before snakes started to differentiate into modern groups.  This Asian fossil helps shed light on how primitive snakes dispersed from the southern to the northern continents.  Although found in the northern hemisphere, it strongly resembles South American snakes that lived at the time.”

An Illustration of the Second Snake Specimen (Life Reconstruction)

Shed snake skin found in burmite.

The preserved skin of a second prehistoric snake has been found in amber from Myanmar.

Picture Credit: Yi Liu

During the Jurassic, the region that we now know as Myanmar was joined to Antarctica, Australia, Africa and South America, forming the giant, southern super-continent of Gondwana.  As the Mesozoic progressed so this landmass began to split apart, Myanmar separated from Gondwana and drifted north, eventually colliding with Asia.

This is the first baby snake fossil from the Mesozoic ever found and it, along with other remarkable specimens preserved in amber from Myanmar (burmite), are providing scientists with a unique window into the Late Cretaceous world.

17 07, 2018

Sad “tail” of a Spanish Plesiosaur

By | July 17th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Photos/Pictures of Fossils|0 Comments

Fossil Discovery Hints at Spanish Elasmosaurid

Recently printed in the academic journal “Cretaceous Research”, a trio of scientists have published details about a new Plesiosaur specimen discovered in Late Cretaceous sediments in Guadalajara Province in central Spain.  Plesiosaur specimens are exceptionally rare from the Late Cretaceous of Europe and although the fossil material is indistinct in terms of any autapomorphies (unique features), that would permit the establishment of a new species, the fragmentary fossils, including a single tail bone, represent an important discovery nonetheless.

An Illustration of a Typical Member of the Plesiosauridae

Attenborosaurus conybeari.

Plesiosaurs swam in the Cenomanian seas of Europe.

Picture Credit: Everything Dinosaur

The First Plesiosauria from Algora

The fossils consist of elements from a pelvic girdle and a caudal vertebra (tail bone).  They are the first evidence of a Plesiosaur in the coastal marine outcrops of Algora (Castilla-La-Mancha), Spain.  It is one of only a handful of such specimens reported from the Cretaceous of Spain.

The Pelvic Girdle Fossil Bones with an Accompanying Line Drawing

Late Cretaceous Plesiosaur fossils from Spain.

The fossils making up part of the pelvic girdle with a line drawing (right).

Picture Credit: N. Bardet, M. Segura and A. Pérez-García/Cretaceous Research

An Elasmosaurid

The fossils probably represent a single individual, as such, it is the only Plesiosaur specimen from central Spain that is known from several bones.  The researchers conclude that the material represents an indeterminate member of the Elasmosauridae.  Elasmosaurids were a type of Plesiosaur that had a wide geographical range during the Late Cretaceous and one that persisted to the end of the Maastrichtian faunal stage.

Views of the Caudal Vertebra (Indeterminate Elasmosaurid)

Photographs (various views) of a Plesiosaur caudal vertebra.

Images of a caudal vertebra (Late Cretaceous Plesiosaur).

Picture Credit: N. Bardet, M. Segura and A. Pérez-García/Cretaceous Research

The authors of the scientific paper include a researcher from the Natural History Museum of Paris (Muséum National d’Histoire Naturelle), as well as two researchers based in Spain.  They suggest that the fossils represent an individual that either died further out to sea and was washed into a bay (thanatocoenosis), or the remains of an animal that lived in a near-shore environment (biocoenosis).

The scientific paper: “A Plesiosaur (Reptilia, Sauropterygia) from the Cenomanian (Late Cretaceous) of Algora (Guadalajara Province, Central Spain)” by N. Bardet, M. Segura and A. Pérez-García published in Cretaceous Research.

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.

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