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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.

19 04, 2018

Carboniferous Shark Brain Case Study

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

Brain Case of Carcharopsis wortheni Described

Research led by American Museum of Natural History scientists has provided a fresh perspective on a shark that might have been the “Jaws” of the Carboniferous.  The shark, Carcharopsis wortheni was first scientifically described in the mid-19th Century and was previously known only from its characteristic serrated teeth and fragments of jaw.  A fossilised brain case identified as C. wortheni was excavated in 2007 from Upper Mississippian aged rocks in Arkansas (Fayetteville Shale).  The fossil was found by Royal Mapes, a retired Ohio University professor and a research associate at the Museum.  State-of-the-art imaging techniques were used to provide a unique insight into this important apex predator that lived some 320 million years ago.

The Fossil Cranium (Brain Case) of Carcharopsis wortheni

The fossilised brain case of C. wortheni.

The brain case of Carcharopsis wortheni.

Picture Credit: American Museum of Natural History/Allison Bronson

Insight into Shark Evolution

The shark lived at a critical point in the evolutionary history of our planet, part of a marine fauna that survived the end Devonian mass extinction event which decimated vertebrate species.  This ancient Palaeozoic shark,  was originally described in 1843 based on its distinctive serrated teeth, a feature that is common in extant sharks such as the formidable Great White (Carcharodon carcharias), an apex marine predator with a frightening reputation, thanks in the main to the film “Jaws” directed by Steven Spielberg, which was based on Peter Benchley’s book.  However, serrated teeth are rarely found in Palaeozoic sharks.

A CT Scan Showing the Unique Serrations on a Tooth from Carcharopsis (C. wortheni)

Shark fossil tooth C. wortheni.

Carcharopsis fossil tooth.  Scale bar = 1 mm.

Picture Credit: American Museum of Natural History/Allison Bronson

The picture above shows a computer tomography generated image of a Carcharopsis tooth, measuring around five millimetres in length.  The blue lines are canals identified within the tooth.

Commenting on the fossil, lead author of the study Allison Bronson, a PhD student at the American Museum of Natural History stated:

“They [the teeth] look a little like what you’d see in a Great White, but are 320 million years old and with different enamel.  This is really early to see serrated teeth.”

Royal Mapes donated the brain case specimen to the New York-based natural history museum, along with a remarkable 540,000 other fossils.  Mapes co-authored the Carcharopsis study, which has been published in the journal “Papers in Palaeontology”, American Museum of Natural History curator John Maisey also contributed to the paper.

The scientists used high-resolution computed tomography (CT) imaging to examine the cranium, a tooth, and an isolated portion of a tooth base.  Using the scans, they were able to reconstruct the internal canals of the teeth for the first time and found that these are similar to the canals found in today’s sharks.

The arrangement of the shark’s blood vessels—also revealed through CT scans—suggests that Carcharopsis was probably closely related to the group of ancient cartilaginous fish from which today’s sharks and rays evolved.  However, more complete fossils are needed to firmly position it in the tree of life.

Everything Dinosaur acknowledges the help of the American Museum of Natural History in the compilation of this article.

17 04, 2018

Out with a Bang, In with a Bang – The Story of the Dinosauria

By | April 17th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Mass Extinction Event Paved the Way for the Dinosaurs

It is now widely accepted that dramatic, global climate change played a significant role in the extinction of the non-avian dinosaurs some 66 million years ago.  The demise of the Dinosauria is well documented, but just how did this particular branch of the Archosauria rise to prominence and just as importantly, when did they start to dominate life on land?  There remains much to be learned about the origins of the dinosaurs, in addition, after the first dinosaurs evolved, for some 20 million years or so they made up only a tiny portion of terrestrial fauna, other reptiles dominated, then all of a sudden, at least when you consider the scale of geological time, the fossil record shows a change in the dinosaur’s fortunes.  From being bit-part players in the Middle Triassic, by the Late Triassic they had taken centre stage.

Research published in the journal “Nature Communications”, postulates that the first, rapid diversification of the dinosaurs occurred following a dramatic global ecosystem crisis.  This crisis was caused by rapid climate change, the ensuring mass extinction event cleared away a lot of competitors, especially herbivores.  A mass extinction event resulted in the demise of the dinosaurs, but it seems likely (according to this new research), that a mass extinction event led to their ascendancy in the first place.

Terrestrial Life Around 234-232 Million Years Ago

Late Triassic terrestrial fauna.

Life in the Late Triassic, an explosion in dinosaur diversity.

Picture Credit: Davide Bonadonna

The picture (above), shows a scene in the early Late Triassic of southern Pangaea around 232 million years ago.  On the far left a pair of Rhynchosaurs (diapsid, herbivorous reptiles characterised by stocky bodies, a squat gait and powerful beaks for cropping plants), lounge on a fallen tree.  In the centre background a large, carnivorous Rauisuchian is patrolling.  Rauisuchians  were Archosaurs, but on the other branch of the Archosauria – the Crurotarsi which comprise crocodile-like animals, as opposed to the second main branch of the Archosaurs the Avemetatarsalia, which houses the birds and the dinosaurs.  The Rauisuchian walks with an erect posture, (legs directly under the body).  In the foreground, two species of light-weight, bipedal early dinosaurs are depicted.

The Carnian Pluvial Episode (Carnian Pluvial Event)

The study conducted by Massimo Bernardi of the MUSE (Museo delle Scienze of Trento) and Piero Gianolla of the University of Ferrara (Italy) in collaboration with Professor Michael Benton of Bristol University, provides evidence to suggest that the diversification of the Dinosauria followed the Carnian Pluvial Episode, a time when the Earth went from an extremely arid climate to a humid and substantially wetter climate, before reverting back to arid once again.  This dramatic period in Earth’s history occurred between 234 and 232 million years ago (during the Carnian faunal stage of the Late Triassic).  The cause of this violent swing in our planet’s weather patterns is elusive, but most palaeontologists consider the huge volcanic eruptions in western Canada and the outpouring of vast quantities of igneous material, which are represented today by the great Wrangellia basalts as the engine for climate change.  What is termed Large Igneous Province (LIP) volcanism, resulted in huge amounts of carbon dioxide being released into the atmosphere.  This led to rapid, ocean acidification, increased rainfall and dramatic global warming turning a dry world dominated by large deserts in central Pangaea, into much more humid and wetter environments.

For Much of the Triassic the Land was Dominated by Deserts

Triassic landscape.

New study suggests the impact of the Carnian Pluvial Episode (CPE) gave dinosaurs the opportunity to diversify.

Dating Ichnoassemblages from the Dolomites

The researchers examined the ancient Triassic fauna of South America and compared these palaeoenvironments with data from the Italian Dolomites.  Although dinosaur and other reptile fossils from Triassic sediments are relatively widespread, for example Triassic vertebrate fossils are known from North America, South Africa, China, Europe and England, accurately dating these deposits has proved to be extremely difficult.  Hence the significance of the Italian Dolomites.  The stratigraphy of the Southern Alps and of the Dolomites in particular covers virtually the whole of the Middle and Late Triassic.  The sequence of strata, can be dated using a variety of methods, which when cross-referenced provides one of the most detailed geological timescales of the early Mesozoic anywhere on Earth.

Dating the Dolomites – A Bio-Chrono-Stratigraphic Framework

Dating the Dolomites.

Dating the Dolomites, a number of dating methods are available to scientists, permitting them to accurately date the rocks and the fossils they contain.

Picture Credit: Nature Communications/Bernardi, Gianolla, et al

Preserved in the rocks of the Dolomites are a series of tracks and trackways.  These footprints provide palaeontologists with an idea of the animals around at the time the sequence of strata was being laid down.  This research team noticed that prior to the Carnian Pluvial Episode, when this part of the world was arid, the tracks were dominated by Crurotarsi Archosaurs, in the early Carnian 100% of the tracks represent these crocodile-like reptiles.  However, during the Carnian Pluvial Episode (CPE), 50% of the tracks represent dinosaurs, whilst just 20% indicate the presence of Crurotarsi Archosaurs, the rest are associated with Dinosauromorphs, close relatives of the true dinosaurs.  As the world entered the Norian faunal stage of the Late Triassic, some 227 million years ago, nearly all the tracks preserved in this region (90% plus) were made by dinosaurs.

The complicated chart above, plots the occurrence of several precisely dated ichnoassemblages in the Late Triassic of the Southern Alps allowing the research team to date, relatively precisely, the timing of the diversification of the dinosaurs in this part of Pangaea.  On the left of the chart is the timeline in millions of years, the Period/Epoch and the faunal stage and sub-stage are noted.  Helping to relatively date the sequence of rocks are the zonal fossils, in this case ammonites, the rocks of this region can be mapped sequentially using key fossil ammonite species which provide a biostratigraphical reference.

The sequence of geological formations are shown and the various ichnotaxa associated with them are displayed.  The scientists identify the probable track maker and describe them as dinosaurs (sky blue), Dinosauromorphs (light green) or Crurotarsans (orange).  The length of the coloured column shows the time interval over which the tracks have been found.

Note the absence of dinosaur tracks in the Middle Triassic (bottom part of the chart), however, blue columns (dinosaur tracks) dominate the top part of the chart, the Late Triassic.  Pie charts show percentage breakdown of the different tracks, pre, during and post the CPE.  The final column on the far right provides details of the palaeoenvironment and the flipping from arid to humid and then back again.

Geological Formations Abbreviations: ADZ: Zoppè Sandstone; AQT: Acquatona Formation; BHL: Livinallongo/Buchenstein Formation; BIV: Bivera Formation; CTR: Contrin Formation; DCS: Cassian Dolomite; DON: Dont Formation; DPR: Dolomia Principale; FCL: Coll’Alto dark Limestones; GLS: Gracilis Formation; HKS: Heiligkreuz Formation; IMF: Fernazza Formation and volcanites; MBT: Ambata Formation; MNA: Moena Formation; MRB/RIC: Richthofen Conglomerate and Morbiac dark Limestone; NTR: Monte Rite Formation; PPS: Piz da Peres Conglomerate; REC: Recoaro Limestone; SCI: Sciliar Formation; SCS: San Cassiano Formation; SLI: Lower Serla Dolomite; SLS Upper Serla Formation; TVZ: Travenanzes Formation; VTG: Voltago Conglomerate; WEN: Wengen Formation.

The small boxes underneath the chart provide a key to the general characteristics of the rocks associated with each geological formation: (a) cherty limestone; (b) sandstone; (c) sandy limestone; (d) volcanics; (e) oolitic-bioclastic limestone; (f) black platy limestone or dolostone, black shale; (g) dolostone; (h) marlstone, claystone and shale; (i) marly limestone; (j) conglomerate.

In summary the lithology (characteristics of the rocks), the length of the sequence of deposition, helping to provide absolute dating information along with the abundance of zonal fossils to permit relative dating, allow scientists to accurately map the geological time represented by the strata.  This precise dating has enabled the researchers to tease out the significance of the CPE in reference to the evolution of the dinosaurs.

The Diversification of the Dinosaurs Coincides with the Carnian Pluvial Episode

The diversification of the dinosaurs.

The diversification of the dinosaurs coincides with the Carnian Pluvial Episode (CPE).

Picture Credit: Everything Dinosaur

Over a period of around 8 million years the palaeofauna of the southern Alps as shown by trace fossils changed dramatically.  Dinosaur trace fossils become much more abundant.  The researchers conclude that the dinosaurs diversified explosively in the mid Carnian, at a time of major climate and floral change and the extinction of key herbivores, which the dinosaurs opportunistically replaced.  The trace fossils found in the Dolomites region therefore play a crucial role in understanding the evolution of the Dinosauria.

Commenting on the significance of the study, one of the authors, Dr Piero Gianolla (University of Ferrara) stated:

“We had detected evidence for the climate change in the Dolomites.  There were four pulses of warming and climate perturbation, all within a million years or so.  This must have led to repeated extinctions.”

The discovery of the existence of a link between the first diversification of the dinosaurs and the CPE is unexpected and revolutionary.  This dramatic event not only paved the way for the dinosaurs to dominate terrestrial ecosystems, but also permitted the diversification of many other types of Tetrapod, including lizards, crocodiles, turtles and mammals, key terrestrial animals in today’s ecosystems.  The scientists conclude that they have developed a new framework for the evolution of the most famous reptiles.

The scientific paper: “Dinosaur diversification linked with the Carnian Pluvial Episode” by Massimo Bernardi, Piero Gianolla, Fabio Massimo Petti, Paolo Mietto and Michael J. Benton published in the journal “Nature Communications”.

15 04, 2018

The Lufengosaurus That Got Away

By | April 15th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Pathology Identified in Lufengosaurus Specimen

An analysis of a 200 million-year-old bite-mark has provided scientists with a detailed picture of a dinosaur’s life.  The bite-mark, preserved on the fossilised rib of a Lufengosaurus (L. huenei) may also provide a clue to how this member of the Sauropodomorpha met its end.  The specimen preserves evidence of an attack on a plant-eating dinosaur, probably from a Theropod and although the attack initially was not fatal, the resulting infection that occurred in the bone may have contributed to the unfortunate dinosaur’s death.

A Life Reconstruction of the Lufengosaurus Showing the Bitemark

Lufengosaurus with bite-mark (life reconstruction).

A life reconstruction of L. huenei in its natural environment and demonstrating the bite wound affecting the shoulder of the herbivorous dinosaur.

Picture Credit: Zongda Zhang

Employing an advanced X-ray technique, an international team of scientists from the UK, China, the United States and South Africa, have published evidence for an unsuccessful attack on a Jurassic dinosaur, a member of the Suborder Sauropodomorpha from China known as Lufengosaurus (L. huenei).  Everything Dinosaur was contacted by one of the authors of the scientific paper, published in the academic journal “Nature Scientific Reports”, a PNSO Lufengosaurus replica was purchased so that the model could be used to help explain the pathology and inferred animal behaviour from the scientific research.

The study provides a detailed report of the first recognised case of an abscess in a long-necked dinosaur from the Lower Jurassic of China, (Yunnan Province), which was caused by infection brought on from the bite of a large predatory dinosaur.  The infection may have weakened the animal, ultimately resulting in its death.

Scientist Lida Xing Holding the Damaged Rib Bone

Rib bone of Lufengosaurus showing pathology.

The pathological fossilised rib of Lufengosaurus huenei.

Picture Credit: Lida Xing

Micro-computed X-ray Tomography

The pathology, was discovered in the skeleton of a L. huenei, which is part of the vertebrate fossil collection at the Yuxi Museum (Yunnan Province).  The fossil rib bone was subjected to micro-computed x-ray tomography (micro-CT).   This permits high-resolution slices and three-dimensional images to be built up of internal structures of bone without damaging the fossil material.  It is a non-destructive research technique.  As well as providing detailed evidence of interactions between big, herbivorous dinosaurs and carnivorous Theropods, the successful identification of this abscess using this technique could point to a new understanding of where certain species lived, and the impact of the diseases that they suffered from.

Commenting on the significance of the research, one of the authors of the scientific paper, Dr Patrick Randolph-Quinney (University of Central Lancashire in the UK and the University of the Witwatersrand in South Africa), stated:

“We were able to use micro-CT to look deep inside the structure of the rib and visualise the precise changes that bacterial infection had caused, as well as to see the region of bone that had been bitten out of the rib.  What micro-CT is allowing us to do is understand processes such as trauma and infection in the fossil record at the cellular level, as well as looking at the whole bone.  This gives us advantages over traditional histology – which slices up bone for magnification under a microscope – in that it doesn’t require us to damage precious fossils and it also allows us to build 3-D reconstructions of the whole region of disease.  In this case, this has allowed us to model and study the whole wound track, not just a single portion of it.”

Images of the Rib Pathology

Lufengosaurus rib pathology caused by a bite.

A 3-D and 3-D slice reconstruction of the Lufengosaurus rib pathology.

Picture Credit: Patrick Randolph-Quinney (University of Central Lancashire)

The picture (above), shows a 3-D and 3-D slice reconstruction of the Lufengosaurus rib pathology.  Micro-computed tomography allowed the scientists to produce surface renderings of the fossil in 3-D (top row) and 2-D X-ray slices through the rib (bottom row).  These images show areas of cellular reorganisation, bone destruction and bone formation indicative of ostemyelitis (bone infection).

Lufengosaurus (L. huenei)

Lufengosaurus grew to about six metres in length.  It is estimated to have weighed around two tonnes.  More than two dozen specimens of this Prosauropod have been discovered to date, adults as well as fossil material from juveniles.  All the fossils ascribed to this genus have been discovered in the Lufeng Formation of south-western China (Yunnan Province).  Yang Zhongjian, known in western literature as Chung Chien Young, formally named and described Lufengosaurus in 1941.  Lufengosaurus was the first dinosaur from China to have been discovered, studied and displayed by Chinese scientists.

The PNSO Lufengosaurus Dinosaur Model Supplied to the Researchers by Everything Dinosaur

PNSO Lufengosaurus replica.

The PNSO Lufengosaurus dinosaur model.

Picture Credit: Everything Dinosaur

Lead author of the study, Dr Lida Xing (China University of Geosciences) added:

“This case is really exciting as it gives us evidence of interactions between large plant-eating dinosaur species and one of the large aggressive predators preying on them at that time.  Using the latest X-ray imaging we were able to track the changes in the bone caused by an infected bite on the Lufengosaurus, probably from a big carnivorous dinosaur.  We don’t just have evidence of disease but of behaviour between animals – between predator and prey at this deep period in prehistory.”

This study was carried out by researchers at the University of Central Lancashire (UCLan), China University of Geosciences, the University of the Witwatersrand in South Africa, the Carnegie Museum of Natural History in the USA, the State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, and the Yuxi Museum, Yunnan, China.

The team were able to identify an infection in the bone called osteomyelitis which produces a pus-filled abscess inside the bone.  This is only the second time that a case of osteomyelitis has been recorded in the Sauropodomorpha, the other instance came from a giant Titanosaur from Argentina, the Lufengosaurus example pre-dates the Argentinian example by tens of millions of years.  It is the earliest recorded case of a bony abscess caused by osteomyelitis disease in the fossil  record.

Views of the Damaged Lufengosaurus Rib Bone

A damaged rib of a Lufengosaurus.

The pathological fossil rib (two views).

Picture Credit: Lida Xing

Hao Ran from the Kunming Institute of Zoology, Chinese Academy of Sciences, commented:

“This is a great example of how the clinical sciences and the science of palaeontology are working together with fossils from the Chinese fossil record.  Together with international collaborators we are able to advance our understanding of diseases in both the past and the present.  We don’t know which predator caused the bite, but we do have a smoking gun of the attack with the bite wound it left.”

The scientific paper: “Possible Bite-induced Abscess and Osteomyelitis in Lufengosaurus (Dinosauria: Sauropodomorph) from the Lower Jurassic of the Yimen Basin, China” by Lida Xing, Bruce M. Rothschild, Patrick S. Randolph-Quinney, Yi Wang, Alexander H. Parkinson and Hao Ran published in Nature Scientific Reports.

9 04, 2018

Late Triassic Giant Ichthyosaurs

By | April 9th, 2018|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Scientists Identify Giant Triassic Ichthyosaur Jaw Bone and Help Solve 19th Century Fossil Mystery

Scientists have identified a jaw bone of a giant marine reptile, that could represent one of the largest animals that ever lived.  The newly described fossil bones, representing a portion of an enormous lower jaw, may also have shed light on a mystery that dates back to the middle of the 19th Century.  The fossilised jaw, which consists of several, broken, individual pieces, is thought to be an incomplete surangular (bone from the rear of the lower jaw), from a shastasaurid Ichthyosaur, a clade of enigmatic, giant marine reptiles that were geographically widespread during the Late Triassic.  The fossil material was found on the beach at the small village of Lilstock in (west Somerset), the specimen is approximately 205 million years old.

A Lateral View of the Fossil Material – A Giant Ichthyosaur from Somerset!

Incomplete surangular from a giant Triassic Ichthyosaur.

The incomplete surangular jaw bone from Lilstock (Somerset).

Picture Credit: Manchester University

Found on a Somerset Beach

Fossil collector and co-author of the study, published in the scientific journal PLOS One, Paul de la Salle, found a portion of the specimen in May 2016.  He later returned to the beach and found more pieces, that together form a partial surangular more than a metre in length (see photograph above).

An Approximate Representation of the Location of Surangular on the Skull of Shonisaurus

The surangular bone of Shonisaurus is highlighted.

A close-up of the skull of Shonisaurus, the surangular bone is outlined in red.

Picture Credit: Scott Hartman with additional annotation by Everything Dinosaur

Commenting on his fossil find Paul stated:

“Initially, the bone just looked like a piece of rock but, after recognising a groove and bone structure, I thought it might be part of a jaw from an Ichthyosaur and immediately contacted Ichthyosaur experts Dean Lomax (Manchester University) and Professor Judy Massare (SUNY College at Brockport, New York, USA), who expressed interest in studying the specimen.  I also contacted Dr Ramues Gallois, a geologist who visited the site and determined the age of the specimen stratigraphically.”

Comparisons with Shonisaurus sikanniensis

Dean Lomax and Judy Massare made the surangular identification and visited the Royal Tyrrell Museum of Palaeontology in Drumheller, southern Alberta (Canada), to view skull material from the largest Ichthyosaur yet described, the monstrous shastasaurid Shonisaurus sikanniensis.  S. sikanniensis fossils come from Upper Triassic rocks found in British Columbia and the Royal Tyrrell material indicates a marine reptile around 21 metres in length.  The researchers found similarities between the new Somerset specimen and Shonisaurus sikanniensis, which suggests that the Lilstock fossils represent a giant shastasaurid too.

A Life Restoration and Skeletal Drawing of the Giant Ichthyosaur Shonisaurus

Shonisaurus life and skeletal reconstruction.

Shonisaurus life restoration and skeletal reconstruction (N. Tamura and S. Hartman).

Picture Credit: Nobumichi Tamura and Scott Hartman

As Big as a Blue Whale?

Commenting on the approximate size of the Somerset specimen, Dean Lomax said:

“As the specimen is represented only by a large piece of jaw, it is difficult to provide a size estimate, but by using a simple scaling factor and comparing the same bone in S. sikanniensis, the Lilstock specimen is about 25% larger.  Other comparisons suggest that the Lilstock Ichthyosaur was at least 20 to 25 metres.  Of course, such estimates are not entirely realistic because of the differences between species.  Nonetheless, simple scaling is commonly used to estimate size, especially when comparative material is scarce.”

When compared to giant marine vertebrates today, the upper end of the size estimate for the Lilstock specimen would indicate a creature longer than the largest toothed whale, the Sperm whale (Physeter macrocephalus), indeed, at around 25 metres long, it would rival in size the largest cetaceans of all, adult Blue whales (Balaenoptera musculus).

A Pair of Giant Shastasaurid Ichthyosaurs Cruise the Late Triassic Ocean with a Pod of Smaller Ichthyosaurs for Company

Shonisaurus illustrated.

A pair of Shonisaurus – giant marine reptiles of the Late Triassic.

Picture Credit: Nobumichi Tamura

Solving a Mystery That Dates Back to 1850

In 1850, a large bone was described from the Upper Triassic sediments of Aust Cliff in Gloucestershire (UK).  Four other fragmentary bone elements were subsequently found and described.  Sadly, two of these fossils are missing and presumed destroyed.  These bone shafts have been assigned to limb bones of herbivorous dinosaurs.  Two of the fossils were thought to resemble the limbs of Stegosaurs, but if that was the case, it would push back the evolutionary origins of Stegosaurs into the Norian faunal stage of the Late Triassic.  Other scientists have speculated that the fossil material might not be dinosaurian at all, but fossils of a related Archosaur from the pseudosuchian lineage.  However, with the discovery of the Lilstock specimen, another possibility has come to light.  These fossils could represent jaw fragments of giant, previously unrecognised Ichthyosaurs, after all, the Aust Cliff location has already yielded a number of marine reptile fossils including Ichthyosaurs.

Dean Lomax added:

“One of the Aust bones might also be an Ichthyosaur surangular.  If it is, by comparison with the Lilstock specimen, it might represent a much larger animal.  To verify these findings, we need a complete giant Triassic Ichthyosaur from the UK – a lot easier said than done!”

The scientific paper: “A Giant Late Triassic Ichthyosaur from the UK and a Reinterpretation of the Aust Cliff “Dinosaurian” Bones by Lomax, D. R., De la Salle, P., Massare, J. A. and Gallois, R. (2018) published in PLOS One.

31 03, 2018

Extinction and Extirpation

By | March 31st, 2018|Dinosaur Fans, Geology, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Defining Extirpation

The fossil record, despite its extremely fragmentary nature remains the best scientific tool available for learning about life in the past.  It is far from complete and it can only provide a limited amount of information about organisms, ecosystems and palaeoenvironments, but it has provided evidence of extinctions and five major mass extinction events have been identified in the immense time period known as the Phanerozoic.

A Selection of Shark Teeth Fossils

fossilised shark teeth.

A successful fossil hunt, but many organisms are only known from fragmentary fossil material.

Picture Credit: Everything Dinosaur

An Extinction is Forever

Notwithstanding the technological developments heralded by advances in genetics, an extinction is finite.  Extinctions represent the complete, world-wide end of the line for a species.  There are no individuals representing that species to be found anywhere.  Non-avian representatives of the Dinosauria, the long-necked Sauropods for example, are extinct, the very last of these animals, collectively termed Titanosaurs, died out at the end of the Cretaceous, some 66 million years ago.

However, it is important to distinguish local extinctions, whereby an organism becomes extinct in a region or area, from true, global extinction.  A species or genus may die out in one part of the area where it is distributed, but it might be thriving, or at least surviving everywhere else.  Identifying local extinctions, especially in an incomplete fossil record, where many of the fossils have been transported long distances and with a record of moving continents (tectonic plate theory), is extremely challenging.

Extirpation

The correct scientific term for a local or regional extinction is “extirpation”, an organism may cease to exist in one area but could still be found in other areas.  Palaeontologists usually use the term extinction in its correct sense, noting the complete disappearance of an organism.  Thanks to the vagaries of the fossil record, identifying extirpation events in deep time is extremely difficult.  The Liaoning Province of northern China has provided scientists with numerous examples of feathered dinosaurs.  Their remains are often beautifully preserved, a result of the way in which these animals may have died .  Corpses were deposited in lakes and sank to the muddy, still bottom before being rapidly buried by fine ash deposited over the region by the nearby volcanoes.  Whether some of these animals drowned, or whether their deaths were directly attributable to the volcanism is difficult to say for certain in most cases.

Zhenyuanlong Fossil (Zhenyuanlong suni) from Liaoning Province

Zhenyuanlong fossil.

Large-bodied, short-armed Liaoning dromaeosaurid described in 2015 (Zhenyuanlong suni).

Picture Credit: Chinese Academy of Geological Science

Unfortunately, whilst a devastating deposit of volcanic ash, perhaps a pyroclastic cloud or the release of toxic carbon monoxide fumes could have led to the deaths of many animals within a habitat, it is very difficult to determine whether such events led to a local extinction (extirpation).  In the case of the Liaoning fossils, the stratigraphic record would indicate numerous volcanic episodes but whether a single episode or a series of catastrophic events led to the demise of an entire taxon in the region it is impossible to say.  However, the forest ecosystem with its large lakes would have suffered a loss of individuals and probably a reduction in diversity over time.

30 03, 2018

Ceratopsian Species – When and Where they Lived (Part 2)

By | March 30th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Geology, Main Page, Palaeontological articles|0 Comments

Ceratopsian Species – Where and When did they Live (part 2)

We conclude our look at the remarkable data that was used to compile a statistical analysis of the Ceratopsia.  The research, published recently in the “Proceedings of the Royal Society B (Biology)”, examined the horned dinosaur family tree and set about building a picture of where and when horned dinosaur species lived.  Using this data, which involved more than seventy species, the scientists were able to conclude that horned dinosaur ornamentation probably evolved, not as a method of telling different species apart, but as a way of demonstrating an individual’s fitness for breeding.  Ostentatious and elaborate crests, horns and frills may have had numerous roles, defence being one, for example, but they would also (most likely), have had a “social-sexual” function.

As a spokesperson from Everything Dinosaur stated:

“All those lumps and bumps, horns and frills were basically signalling to other members of the species – look how big and strong I am, I can carry around all this extra weight, so I must be a healthy horned dinosaur and therefore an ideal mate!”

To read our original article on the Ceratopsian research: Why Did Horned Dinosaurs Have Fancy Frills?

The supplementary data associated with the scientific paper included some fantastic details of the Ceratopsian family tree.  In order to conduct their analysis, the research team compiled a table of horned dinosaurs and listed where they lived and approximately when (upper and lower margins of stratigraphical distribution).  In an earlier article, we published the first part of this extensive table, today, we conclude our blog articles on this fascinating piece of Ceratopsian research by posting up the rest of the data.

Plotting Ceratopsian Species Against Temporal and Geographical Distribution (Part 3)

Ceratopsian species - where they lived and when (part 3).

Temporal calibrations and geographical locations of Ceratopsian species (part 3).

Table Credit: Andrew Knapp, Robert J. Knell, Andrew A. Farke, Mark A. Loewen, David W. E. Hone published in the Proceedings of the Royal Society B (Biology).

The table (above), shows part 3 of the temporal calibrations and geographical locations of Ceratopsian species. Taxa that were included in the morphological character state analysis (the research into crests and horns), are indicated in bold type.  Region abbreviations: Asia: A; North America: NA; Europe: E.  The source of the table data is shown on the right.

This  part of the Ceratopsian table helps to demonstrate the diversity of the horned dinosaurs in North America during the Late Cretaceous, especially on the western part of the continent, the landmass known as Laramidia.

The Ornamentation of Diabloceratops (D. eatoni) was Included in the Study

Collecta Diabloceratops dinosaur model.

“Devil Horned Face” – Diabloceratops eatoni.

Picture Credit: Everything Dinosaur

Campanian and Maastrichtian Stages

Tables (3 and 4) list the horned dinosaur species from the later stages of the Cretaceous (Campanian and Maastrichtian).  In part 4 (shown below), the dominance of Ceratopsian species from North America continues with a further nineteen North American species listed.

Plotting Ceratopsian Species Against Temporal and Geographical Distribution (Part 4)

Ceratopsian species - where they lived and when (part 4).

Temporal calibrations and geographical locations of Ceratopsian species (part 4).

Table Credit: Andrew Knapp, Robert J. Knell, Andrew A. Farke, Mark A. Loewen, David W. E. Hone published in the Proceedings of the Royal Society B (Biology).

The Very Last of the Horned Dinosaurs

The last parts of the data table focus on the youngest species of horned dinosaur known.  These are the Ceratopsians that lived during the last few million years of the Cretaceous.  Once again, North America is the only continent represented in this part of the table.  This does not mean that horned dinosaurs were extinct elsewhere in the world, that cannot be inferred from the information provided, but it is worth noting that no Asian horned dinosaurs for example, are known from the Maastrichtian faunal stage of the Late Cretaceous.

Plotting Horned Dinosaur Species Against Temporal and Geographical Distribution (Part 5)

Ceratopsian Species - where they lived and when (part 5).

Temporal calibrations and geographical locations of Ceratopsian species (part 5).

Table Credit: Andrew Knapp, Robert J. Knell, Andrew A. Farke, Mark A. Loewen, David W. E. Hone published in the Proceedings of the Royal Society B (Biology).

Last of All Triceratops prorsus

The last three species listed are all believed to be the youngest of the horned dinosaurs described so far, in terms of geological age.  The two species of Triceratops are known from the Hell Creek Formation, whilst the controversial Nedoceratops (known from only one skull and therefore thought by some palaeontologists to be nomen dubium), comes from the Lance Formation of Wyoming.  All three species are classified as members of the Ceratopsidae sub-family Chasmosaurinae, which with Torosaurus also a Chasmosaur (T. latus listed in table 5), suggests that Centrosaurine dinosaurs may not have persisted to the very end of the Age of Dinosaurs.

Plotting Horned Dinosaur Species Against Temporal and Geographical Distribution (Part 6)

Ceratopsian species - where and when they lived (end).

Temporal calibrations and geographical locations of Ceratopsian species (end of the Maastrichtian stage).

Table Credit: Andrew Knapp, Robert J. Knell, Andrew A. Farke, Mark A. Loewen, David W. E. Hone published in the Proceedings of the Royal Society B (Biology).

Triceratops – One of the Very Last of All the Dinosaurs

Schleich Triceratops dinosaur model (2018).

The new for 2018 Schleich Triceratops dinosaur model.

Picture Credit: Everything Dinosaur

We once again congratulate the researchers for producing such an amazing study and for making available in the supplementary data all these really informative tables.

For the first part of our review of the Ceratopsian data tables: Ceratopsian Species – When and Where They Lived (Part 1)

27 03, 2018

Ceratopsian Species – When and Where they Lived (Part 1)

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

Ceratopsian Species – Where and When did they Live (part 1)

A few days ago, Everything Dinosaur published an article which summarised some remarkable research into the Ceratopsian family tree undertaken by a team of international scientists.  This research team, that included researchers from the University of London, postulated that all those fancy frills and horns associated with the horned dinosaurs, probably evolved to help individuals attract a mate.  This statistical study involved mapping when different species of horned dinosaur lived, where they lived and what other Ceratopsians may have been contemporaneous.

In the supplementary data, the researchers provided a marvellous Ceratopsian family tree plotted against geological time.  Quite a feat considering more than seventy species of horned dinosaur were analysed.  In addition, the team published very useful tables that summarised the data they had compiled.  The table listed the horned dinosaurs and provided information about which continent their fossils had been found and calibrated their approximate ages (upper limit and lower limit of stratigraphical distribution).

Plotting Ceratopsian Species Against Temporal and Geographical Distribution

Ceratopsian species and temporal calibration/geographical location.

Temporal calibrations and geographical locations of Ceratopsian species (part 1).

Table Credit: Andrew Knapp, Robert J. Knell, Andrew A. Farke, Mark A. Loewen, David W. E. Hone published in the Proceedings of the Royal Society B (Biology).

The table (above) shows temporal calibrations and geographical locations of Ceratopsian species.   Taxa that were included in the morphological character state analysis (the research into horns and crests), are indicated in bold type.  Region abbreviations: Asia: A; North America: NA; Europe: E.

One of the earliest Ceratopsians described to date is Yinlong downsi, fossils of which were found in Upper/Middle Jurassic aged rocks in Xinjiang Province (western China).  It is likely that the Ceratopsian lineage originated in the Middle Jurassic and that these bird-hipped dinosaurs first evolved in Asia.

An Illustration of Yinlong downsi – An Early Ceratopsian

An illustration of Yinlong downsi.

Yinlong downsi, an early Ceratopsian dinosaur.  The first horned dinosaurs were very probably small and bipedal.

Picture Credit: Everything Dinosaur

Building on the Shoulder of Giants

The research team collated a significant amount of data that had been produced by other scientists.  Using this extensive research (source of the data is recorded in the table), a table listing Ceratopsian species, where they lived and when they lived was produced.

Plotting Ceratopsian Species Against Temporal and Geographical Distribution (Part 2)

Ceratopsian species - where they lived and when (part 2).

Temporal calibrations and geographical locations of Ceratopsian species (part 2).

Table Credit: Andrew Knapp, Robert J. Knell, Andrew A. Farke, Mark A. Loewen, David W. E. Hone published in the Proceedings of the Royal Society B (Biology).

The second part of the table lists horned dinosaurs from the Late Cretaceous (majority) and also includes the first reference to a horned dinosaur from Europe Ajkaceratops kosmai, which is known from anterior portions of the skull and jaws discovered in Hungary.

To read our article from 2010, which discusses the discovery of the first European Ceratopsian (A. kosmai): Evidence of European Ceratopsians Grows With Hungarian Discovery

We congratulate the research team conducting the statistical study into the ornamentation of the Ceratopsia and praise all those patient, dedicated scientists that helped to provide the data set for them to work on.  A second article will be published shortly that features the rest of the horned dinosaur temporal and geographical distribution table.

To read our original article on the Ceratopsian research: Why Did Horned Dinosaurs Have Fancy Frills?

To view the timeline of Ceratopsian species – (a family tree of horned dinosaurs): A Horned Dinosaur Family Tree Plotted Over Geological Time

25 03, 2018

A Horned Dinosaur Family Tree

By | March 25th, 2018|Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Ceratopsia Family Tree

Recently, Everything Dinosaur posted up an article that featured some remarkable research by an international team of scientists who set about answering the question, why did horned dinosaurs have fancy frills?  The scientific paper detailing this fascinating study, undertaken by scientists from the Natural History Museum of Utah, the Raymond M. Alf Museum of Palaeontology (California) and the University of London has been published in the “Proceedings of the Royal Society B.”

To read our article: Why Did Horned Dinosaurs Have Fancy Frills?

The researchers conclude that there is no statistical evidence to support the idea that the elaborate horns, neck frills and bony outgrowths associated with the skulls of the Ceratopsia evolved to help with inter-species recognition.   If a Centrosaurus (Centrosaurus apertus), happened to encounter an Achelousaurus (A. horneri), then it is likely that they used more subtle signals to help distinguish themselves.  Although, inter-species recognition is discounted, the paper suggests that the amazing skull ornamentation evolved as a sign that the individual was genetically healthy and therefore an attractive mate.

The Horns of Triceratops Probably Played a Role in Demonstrating Fitness for Breeding

Triceratops dinosaur illustration.

Triceratops was one of the last dinosaurs to evolve and its horns probably played a role in demonstrating fitness for breeding as well as defence.

Picture Credit: Julius Csotonyi

How Many Horned Dinosaurs and When Did They Live?

Before the statistical analysis could be carried out, the dedicated research team had to create a pool of horned dinosaur data to work with.  To test the idea about fancy frills and huge horns having something to do with inter-species identification, the scientists had to work out when the species of horned dinosaur lived, where they lived and what other horned dinosaurs shared their habitat.  In essence, an audit of the stratigraphical, geological and temporal evidence for the Ceratopsia (more than 70 species), had to be constructed.

Drawing on numerous sources, the research team compiled a time-scaled phylogeny for all the known Ceratopsians.  When each species of horned dinosaur lived was plotted against the geological timescale.  In this way, a single chart could show which horned dinosaurs were contemporaneous.

When the Horned Dinosaurs Lived (Ceratopsians) Plotted Against Geological Time

Phylogeny of the Ceratopsia (spring 2018).

The Ceratopsia family tree (spring 2018).

Picture Credit: Published in the Supplementary Section of the Scientific Paper*

The picture (above), shows a time-scaled phylogeny for all the Ceratopsian species known at the time of compilation.  Estimated temporal range of each species is indicated by the thick, black bars at the branch tips.  This phylogeny was created using strap package for R. (Bell and Lloyd, 2014).

From their Middle Jurassic origins, the evolution of the horned dinosaurs can be outlined in a single figure.  Dinosaur fans can see which Ceratopsians lived at the same time as each other.  They can also observe which horned dinosaurs are associated with the various faunal stages that make up the Jurassic and the Cretaceous.

The very last horned dinosaurs include the likes of Nedoceratops hatcheri, Torosaurus latus and Triceratops prorsus, this information can be found towards the bottom corner of chart.  Note how the two recognised species of Triceratops T. horridus and the geologically younger T. prorsus are not contemporaneous.  This reflects recently published research (2014), that mapped changes in the Triceratops fossil population and the evolution of a new species as the genus changed over time.

To read the article on the evolution of species within the Triceratops genus: How Triceratops Got Its Horns and Beak

*The scientific paper:  “Patterns of Divergence in the Morphology of Ceratopsian Dinosaurs: Sympatry is not a Driver of Ornament Evolution” by Andrew Knapp, Robert J. Knell, Andrew A. Farke, Mark A. Loewen, David W. E. Hone published in the Proceedings of the Royal Society B (Biology).

23 03, 2018

Why Did Horned Dinosaurs Have Fancy Frills?

By | March 23rd, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Why Did Horned Dinosaurs Have Fancy Frills (and Horns Too for that Matter)?

One of the great pleasures of working with so many young dinosaur enthusiasts is that we get to answer lots of their amazing questions.  We do get asked all sorts of things, such seems to be the fascination with dinosaurs and other prehistoric animals.  Scientists get to ask questions too, after all, the essence of scientific enquiry is all about seeking answers.  It is surprising just how often the question asked of us by an eight-year-old overlaps with the sort of enquiries being explored by palaeontologists.  Take for example, the question of why did horned dinosaurs have horns and frills?  Thanks to a some recently published fascinating statistical analysis, researchers are able to at least rule out one possible explanation for these very ornate and often bizarre examples of dinosaur head gear.

Writing in the “Proceedings of the Royal Society B (Biology)”, researchers have concluded that all this ornamentation probably did not evolve to help a dinosaur distinguish itself from another species.  Yes, they may have had a role in defence, after all, many of the later Ceratopsians had to contend with Tyrannosaurs in their neighbourhood, but this new analysis lends weight to the idea that the diverse range of headgear sported by horned dinosaurs probably evolved to help them win mates.

Lots of Horned Dinosaur Species – But Why all the Different Horns and Ornamentation?

So many different horned dinosaurs.

Illustrations of different horned dinosaurs but why the fancy headgear?

Picture Credit:  Everything Dinosaur with artwork from Julius Csotonyi, Danielle Dufault and the Canadian Museum of Natural History/Andrey Atuchin

A Statistical Study of Ceratopsians

The research team which included scientists from the University of London, the Natural History Museum of Utah and the Raymond M. Alf Museum of Palaeontology in California, first set about building a list of all the known horned dinosaurs that had been described to date.  The Ceratopsia (horned dinosaurs), is a major clade of the bird-hipped dinosaur lineage, it contains over seventy species, all of which possessed some form of skull ornamentation, from the small “sticky-out” cheek horns of Psittacosaurus from the Early Cretaceous to the spectacular multi-faceted head crests and horns sported by Late Cretaceous giants such as Styracosaurus, Triceratops and Pachyrhinosaurus that lived some fifty million years later.

Members of the Ceratopsia with Differing Ornamental Traits

Comparing the skulls of Triceratops and Psittacosaurus.

Ornamental traits in the Ceratopsia. Psittacosaurus and Triceratops compared.

Picture Credit: Everything Dinosaur

These horned dinosaurs had very different shaped skulls and to test the idea that these features evolved to help with species recognition, the researchers then set about looking at which horned dinosaurs lived at the same time and in the same parts of the world.  In essence, they looked to see if any two species were sympatric – this simply means whether two species live in the same area at the same time and therefore encounter each other.  A modern example can be found in the Serengeti National Park, where Impalas and Grant’s Gazelle, two species of antelope, live side by side.  There is sympatry between Impalas and Grant’s Gazelle.

Diverse Skulls – All Shapes and Sizes

Once the fossil records for all the known species of Ceratopsian had been analysed by location and when these animals lived, the team set about looking at the physical features of all those species which had enough fossil material associated with them to make any analysis statistically valid.  To test the idea that these horns and frills evolved to help in species recognition, there should be some evidence that at some point, several closely related species with different ornamentation lived at the same time in environments that at least partially overlapped and therefore these animals would have encountered each other.

Horned Dinosaur Skulls Come in All Shapes and Sizes

Line drawings of horned dinosaur skulls.

Line drawings of Ceratopsian skulls showing different morphology.

Picture Credit: Proceedings of the Royal Society B (Biology)/Scott Hartman

The picture above shows seven line drawings of horned dinosaur skulls namely:

a).   Liaoceratops yangzigouensis – from Asia with a temporal range of 125 to 121 million years ago (Aptian faunal stage of the Early Cretaceous)

b).  Protoceratops andrewsi – from Asia with a temporal range of 76.38 to 72.05 million years ago (Campanian faunal stage of the Late Cretaceous)

c).  Centrosaurus apertus – from North America with a temporal range of 77 to 75.5 million years ago (Campanian faunal stage of the Late Cretaceous)

d).   Achelousaurus horneri – from North America with a temporal range of 75.8 to 74 million years ago (Campanian faunal stage of the Late Cretaceous)

e).  Pachyrhinosaurus canadensis – from North America with a temporal range of 72 to 68.3 million years ago (Campanian/Maastrichtian faunal stage of the Late Cretaceous)

f).  Chasmosaurus belli – from North America with a temporal range of 77 to 76 million years ago (Campanian faunal stage of the Late Cretaceous)

g).  Triceratops horridus – from North America with a temporal range of 66.8 to 66.4 million years ago (Maastrichtian faunal stage of the Late Cretaceous)

The red node 1 represents the clade Coronosauria a sub-division of the Ceratopsia that contains all the horned dinosaurs with enlarged frills.  Node 2 represents the clade Ceratopsoidea, which is split into two branches, the Centrosaurinae (orange branch) and the Chasmosaurinae (blue branch).  It is these two branches, the Centrosaurines and the Chasmosaurines that exhibit the majority of the cranial ornamental diversity.

Looking at Traits/Examining Characteristics

The next step was to classify those differences in the skeleton to separate out any features that may have played a role in inter-species recognition.  The scientists looked for anatomical traits within the skeleton.  Each trait was classed as either external or internal, based on whether it was likely to have an effect on the exterior appearance of the animal in life.  External characters were further subdivided into display and non-display, defined as whether or not the character or trait in question was deemed whole or part of an ornament (i.e. in Ceratopsians, the frill, horns and bosses of the skull).

An Example of the Traits Identified by the Researchers (Styracosaurus)

Styracosaurus skeleton showing examples of traits used in the study.

A skeletal reconstruction of the Centrosaurine dinosaur Styracosaurus (S. albertensis).

Picture Credit: Proceedings of the Royal Society B (Biology)/Scott Hartman

The statistical analysis found no evidence to support the idea that the horns and frills of Ceratopsians evolved to help these animals differentiate themselves from other species that they shared habitats with.

Palaeontologist David Hone (University of London), explained that this study suggests that these ornamentations evolved as “social-sexual functions” i.e. as both males and females of each species had similar ornamentation, the horns and frills evolved to help advertise the animal’s condition and fitness for breeding.

He stated:

“We think that, really, it’s mostly a big kind of display feature, so just as peacocks have the big showy feathers and lions have the big mane and deer have big antlers.  It’s some kind of big advertising feature for these animals to show off.”

Billboards for Mutual Attraction

These skull ornamentations may have been a horned dinosaur’s way of demonstrating that it was healthy, strong and had good genetic make-up.  In short, both males and females were advertising their fitness for mating.  In evolutionary terms, the more fantastic your head crest and the bigger the lumps, bumps and horns on your face the dinosaur is highlighting that it is fit and healthy. It shows that it can grow lots of bone and carry it around without suffering from any disadvantages, such as being too slow and heavy to avoid a T. rex.

Those Skull Features – Basically They Communicate Fitness for Breeding

Yehuecauhceratops Museum Replica

Scientists have constructed a model of the Mexican dinosaur called Yehuecauhceratops.  Those horns, crests and frills probably advertise the animal’s fitness for breeding.

Picture Credit: Museo del Desierto, Mexico (The Coahuila Desert Museum)

The researchers conclude that the theory that all this ornamentation evolved as a species recognition mechanism, has no statistical support among known Ceratopsians.

The various features associated with the vast and diverse family of horned dinosaurs probably had other functions too.  Perhaps they played a role in thermoregulation and they may have functioned as defensive structures, plus they could have had a role in visual communication and display.  However, the idea that they developed to aid with inter-species recognition has been rejected by this research team.

The next time we get asked by an eight-year-old why did Triceratops have horns?  We can provide a more complete answer…

The scientific paper: “Patterns of Divergence in the Morphology of Ceratopsian Dinosaurs: Sympatry is not a Driver of Ornament Evolution” by Andrew Knapp, Robert J. Knell, Andrew A. Farke, Mark A. Loewen, David W. E. Hone published in the Proceedings of the Royal Society B (Biology)

14 03, 2018

Are Palaeontologists Naming Too Many New Species?

By | March 14th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Cautionary Tale When It Comes to Naming New Species from Fragmentary Fossils

In the 19th Century when scientists were beginning to understand that there were many different types of dinosaur, lots of new species were erected, often from the most fragmentary of fossils.  As the western United States and Canada were explored, large quantities of dinosaur fossil material came to light.  This led to palaeontologists naming many new species.  Famous dinosaurs such as the hadrosaurid Trachodon (T. mirabilis), which graced an amazing number of dinosaur books in the 1960’s and 1970’s, named in 1856 by the American palaeontologist Joseph Leidy, is a typical example.  Leidy described Trachodon from just a few teeth found in Montana (Judith River Formation).  Today, palaeontologists regard the genus Trachodon as nomen dubium (its validity is doubted).   Those teeth used to describe this iconic duck-billed dinosaur probably represent several different plant-eating dinosaurs both Hadrosaurs and even horned dinosaurs (Ceratopsians).

As Seen in Numerous Dinosaur Books in the Late 20th Century – Trachodon

Postcard with Trachodon illustration.

An illustration of Trachodon.  A genus of dinosaur regarded as nomen dubium (validity is questioned).

Picture Credit: Everything Dinosaur

Recognising new Fossil Species

It is not just the Dinosauria that has suffered from overzealous species naming, however, a comprehensive review of variations in Ichthyosaur bones will help scientists to recognise new fossil species.  Dean Lomax (Manchester University) and Professor Judy Massare (SUNY College at Brockport, New York, USA), have examined hundreds of Ichthyosaurus specimens and they urge caution when it comes to erecting new species based on the evidence of a few fragmentary elements or isolated fossil remains.

Writing in the “Geological Journal”, the pair of scientists report that by focusing on just one part of the anatomy of an Ichthyosaurus an appreciation of the variation within a species can be obtained.  Their paper looked at the hind fin, (back paddle), the purpose being to evaluate different forms amongst the six known species that make up the Ichthyosaurus genus.  In total, ninety-nine specimens were examined, providing useful information on the variations within different species of “fish lizard”.

A Fossil Specimen of Ichthyosaurus somersetensis Named and Formally Described in 2017

Ichthyosaurus somersetensis specimen.

Ichthyosaurus somersetensis fossil specimen.  The black arrow in the photograph shows the location of the hind fin.

Picture Credit: Dean Lomax/Manchester University

Large Sample Size Helps to Provide Robust Results

Early in their research, the scientists found different types of hind fin that initially appeared to represent different species.  As more specimens were studied, they found further examples of variation between the hind fins of individual animals.   The hind fins differed in a number of ways, hind fins had different numbers of bones, their shape differed and the size of the hind fin also varied.  From this work, it was concluded that a single hind fin alone could not be used to distinguish amongst the species of Ichthyosaurus, however, particular variations were more common in certain species than in others.

Palaeontologist Dean Lomax explained:

“As we have such a large, complete sample size, which is relatively unique among such fossil vertebrates, our study can help illustrate the limitations that palaeontologists face when dealing with few or even just one specimen.”

This new study shows that with only a few specimens in the sample, features can be found that differ substantially from one specimen to the next and this can cause confusion if these autapomorphies (distinctive traits) are used to classify organisms.  It can appear that there are several species.  In reality, with a much bigger sample, the gaps in the “unique” variations are filled in, showing that differences are simply the result of individual variations within a population.

Judy Massare added:

“We described a few hind fins, which might have been called a new species if they were found in isolation.  Instead, we had enough specimens to determine that it was just an extreme variation of a common form.”

How Many Types of Ichthyosaurus Existed?

A Jurassic marine scene (Ichthyosaurus).

Ichthyosaurus life restoration.

Picture Credit: James McKay

“Lumpers” and “Splitters”

Palaeontologists can be put into two distinct groups when it comes to naming new species, the “lumpers” and the “splitters”.   “Lumpers” group similar specimens together, whilst in contrast, the “splitters” opt to split specimens into new species.  In this new study, if the team opted to split-up the specimens based on the variation found, it would suggest that there were a large number of species.

Dean Lomax stated:

“If we considered the variation as unique, it would mean we would be naming about 30 new species.  This would be similar to what was done in the 19th Century when any new fossil find, from a new location or horizon, was named as a new species if it differed slightly from previously known specimens.”

Just like the example of Trachodon given above.

As more fossil material is found and better dating techniques are developed, the decision to erect a new species has to be given extremely careful consideration.  This new study into variation within an extinct group of individual specimens can help scientists to make appropriate choices when it comes to classification.

The scientific paper: “Hindfins of Ichthyosaurus: effects of large sample size on ‘distinct’ morphological characters” by Judy A. Massare and Dean R. Lomax published in the Geological Journal.

Everything Dinosaur acknowledges the help of Manchester University in the compilation of this article.

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