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Fossil finds, new dinosaur discoveries, news and views from the world of palaeontology and other Earth sciences.

17 09, 2020

Carnian Pluvial Episode – Late Triassic Mass Extinction

By | September 17th, 2020|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Geology, Main Page, Palaeontological articles|0 Comments

Getting to Grips with a Mass Extinction Event – Carnian Pluvial Episode

The fossil record of the Phanerozoic (the Eon of visible life), indicates that there were five major mass extinction events.  The fossil record marks huge and very rapid (at least in geological terms anyway), reductions in the diversity of life on a world-wide scale.  Our planet might well be going through a mass extinction event at the moment, but for one team of scientists their attention has been on the Late Triassic (Carnian faunal stage), plotting a time of extensive terrestrial and marine faunal turnover.  The researchers, which include scientists from Bristol University, the University of Ferrara (Italy), the University of Vienna and the China University of Geosciences in Wuhan Province, conclude that around 233 million years ago about a third of all marine genera disappeared.

Terrestrial Fauna in the Late Triassic – Did a Major Extinction Event Help to Trigger the Rise of the Dinosaurs

Late Triassic terrestrial fauna.

Life in the Late Triassic, an explosion in dinosaur diversity.  Did the Crocodylomorpha and the Dinosauria benefit from the Late Triassic Carnian Pluvial Episode?

Picture Credit:  Davide Bonadonna

Many types of land-living animal did no better.  The herbivorous rhynchosaurs and dicynodonts were greatly reduced in diversity during the Carnian, but intriguingly crocodylomorphs and those other archosaurs, the Dinosauria seem to have benefitted from the extinction of other types of tetrapod, with both the Crocodylomorpha and dinosaurs diversifying towards the end of the Carnian.  The scientists postulate that the rise of the dinosaurs to dominance might have been a direct consequence of the Carnian Pluvial Episode (CPE).

To read an earlier blog article that links the CPE with dinosaur diversification: Out with a Bang! In with a Bang! The story of the Dinosauria.

 A Time of Immense Global Environmental Change

The Carnian Pluvial Episode took place from around 234 to 232 million years ago.  There was a marked rise in rainfall (at least four episodes of increased rainfall have been deduced from sedimentary and palaeontological data).  The Earth got warmer and more humid.  This led to extensive environmental changes and the subsequent demise and then collapse of many ecological systems.  Writing in the academic journal “Science Advances”, the scientists throw their collective weight behind the theory that enormous volcanic eruptions in the Wrangellia Province of western Canada, that resulted in the deposition of vast amounts of basalt, were probably the cause of the global environmental changes.

Co-author of the paper Jacopo Dal Corso (China University of Geosciences), explained:

“The eruptions peaked in the Carnian.  I was studying the geochemical signature of the eruptions a few years ago and identified some massive effects on the atmosphere worldwide.  The eruptions were so huge, they pumped vast amounts of greenhouse gases like carbon dioxide and there were spikes of global warming”.

This warming resulted in the increased humidity and higher levels of rainfall, a phenomenon first detected by geologists Mike Simms and Alastair Ruffell in the 1980s.  The climate change caused major biodiversity loss in the ocean and on land, but just after the extinction event new groups took over, forming more modern-like ecosystems.

Environmental and Geochemical Changes of the CPE

Environmental and geochemical changes associated with the Carnian Pluvial Event.

(A) Calculating the age of the CPE based on geochemical indicators and (B) Palaeogeography during the Carnian, the map showing where sedimentary and palaeontological data has been obtained documenting changes in environmental conditions.

Picture Credit: Jacopo Dal Corso et al/Science Advances

The environmental changes had a profound effect on life on our planet.  As well as a diversification of the dinosaurs, many other modern groups of animals and plants appeared at this time, including lizards and the first mammals.  When mapping the losses of marine fauna at the genus level, the team concluded that whilst the CPE was not as devastating as the either the end-Triassic or end-Cretaceous extinction events, some 33% of all marine genera died out.

A Comparison of Marine Faunal Turnover During Major Extinction Events

Plotting marine extinctions and faunal turnover over the Carnian Pluvial Event.

(A) Comparison of extinction rates of all marine genera during the CPE with those of major Phanerozoic mass extinction events.

Picture Credit: Jacopo Dal Corso et al/Science Advances

The Effect on Plant Life

The shifts in climate encouraged substantial changes in global flora too.  Many new types of plants emerged that were more suited to the humid climate.  Several modern fern families emerged and the Bennettitales (cycad-like plants), diversified.  Extensive coal deposits formed once again, the first substantial coal seams being produced since the Permian.  Conifers seem to have benefitted and the researchers, which include Professor Mike Benton (Bristol University), remark that the CPE provides the first major finds of amber in the fossil record.  As tree resin is usually produced when plants are under stress, this suggests that terrestrial ecosystems were in a state of flux during this period in Earth’s history.

Professor Benton stated:

“The new floras probably provided slim pickings for the surviving herbivorous reptiles.  I had noted a floral switch and ecological catastrophe among the herbivores back in 1983 when I completed my PhD.  We now know that dinosaurs originated some 20 million years before this event, but they remained quite rare and unimportant until the Carnian Pluvial Episode hit.  It was the sudden arid conditions after the humid episode that gave dinosaurs their chance.”

Terrestrial Extinctions and Originations During the Carnian (Late Triassic)

Mapping the major biological changes amongst plants, insects and vertebrates during the Carnian.

Plotting the major biological changes amongst plants, insects and vertebrates during the Carnian.  Trackmaker assemblages from the Southern Alps suggest a faunal turnover within the Archosauria with the dinosaurs replacing the crocodylomorphs as a significant component of terrestrial ecosystems.

Picture Credit: Jacopo Dal Corso et al/Science Advances

The researchers conclude that the CPE may not have been as significant as the big five Phanerozoic mass extinctions but it did have a dramatic impact on terrestrial and marine environments and helped to bring in a variety of new types of plants and animals, marking an important step towards the origins of the types of ecosystems we see around us today.

The scientific paper: “Extinction and dawn of the modern world in the Carnian (Late Triassic)” by Jacopo Dal Corso et al published in Science Advances.

11 09, 2020

A Dinosaur “Begs” to Differ

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A Neoceratopsian from Mongolia – Beg tse

A new species of basal neoceratopsian has been described from fossils found near the town of Barunnbayan in the Gobi Desert of Mongolia.  The little dinosaur, which was probably less than a metre long, has been named Beg tse in honour of the Himalayan deity Beg-tse.  In Mongolian culture, prior to the spread of Buddhism, Beg-tse was a god of war, often depicted as heavily armoured with large, roughened patches on its body.  The researchers studying the fossil material noted that, like other members of the Neoceratopsia, Beg had rugosities (roughened areas), on its skull, notably on the jugal and the surangular.

The Compressed Skull of Beg tse with an Accompanying Line Drawing

Beg tse skull and line drawing.

Lateral view of the holotype skull of Beg tse with line drawing.  The compressed skull measures 14 cm in length approximately.

Picture Credit: Yu et al (Nature)

The Most Basal Neoceratopsian Described to Date

The only known specimen of Beg tse (specimen reference: IGM 100/3652), was discovered by a joint American Museum of Nature/Mongolian Academy of Sciences expedition in 2015.  The fossils probably represent a single individual and consist of an articulated partial skull along with postcranial elements consisting of a fragmentary right ischium, a partial left scapula, one rib bone and numerous bone fragments.  A phylogenetic analysis conducted by the scientists, which included Dr Mark Norell (American Museum of Natural History),  indicates that Beg is the most basal neoceratopsian dinosaur known to date and is more derived than both the Psittacosauridae and Jurassic Chaoyangsauridae.

A Speculative Life Reconstruction of the Basal Neoceratopsian Beg tse

Beg tse life reconstruction.

A speculative life reconstruction of the basal neoceratopsian Beg tse.  The illustration has been based on the neoceratopsian Liaoceratops yanzigouensis from north-eastern China.

Picture Credit: Everything Dinosaur

Proving Difficult to Date

It is difficult to estimate the date of the fossil bearing strata for many of the Gobi Desert dig sites due to the lack of detailed geological mapping and the limited number of sediments suitable for radiometric dating.  The sandstone dominated deposit has been dated to between 113 – 94 million years ago, with a most probable date of circa 100 million years ago.  As a result, the researchers conclude that Beg dates from the latest Early Cretaceous or the earliest Late Cretaceous.  The Ceratopsia may have originated around the Middle Jurassic, but the skull of Beg tse exhibits a combination of primitive and more derived traits which suggests that the basic ceratopsian bodyplan persisted until at least the Early-Late Cretaceous boundary.  Beg along with other Asian neoceratopsians such as Auroraceratops and Mosaiceratops represent transitional forms between basal ceratopsians and more derived forms.  With a wide geographical range from South Korea, China and Mongolia and a long time span from the Aptian to possibly the Campanian, the early evolutionary history of the horned dinosaurs is probably much more complex than previously thought.

The scientific paper: “A neoceratopsian dinosaur from the early Cretaceous of Mongolia and the early evolution of the ceratopsia” by Congyu Yu, Albert Prieto-Marquez, Tsogtbaatar Chinzorig, Zorigt Badamkhatan and Mark Norell published in Nature (Communications Biology).

8 09, 2020

Eternal Sleeping Dinosaur Discovery

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Changmiania liaoningensis A New Basal Ornithopod from Liaoning Province

A new species of basal ornithopod dinosaur has been named and described from Liaoning Province in north-eastern China.  The dinosaur has been named Changmiania liaoningensis which translates from the Chinese as “eternal sleeper from Liaoning”.  The researchers which include Pascal Godefroit of the Royal Belgian Institute of Natural Sciences and Paul-Emile Dieudonné (Universidad Nacional de Río Negro, Argentina), in collaboration with colleagues from Jilin University and Shenyang Normal University (China), postulate that Changmiania lived in burrows.

The Holotype of Changmiania liaoningensis (PMOL AD00114) and a Life Reconstruction

Changmiania liaoningensis fossil material and life reconstruction.

The perfectly preserved holotype fossil of Changmiania liaoningensis with a life reconstruction.  The very nearly intact, articulated specimens suggest that the dinosaurs were entombed in their burrows during a volcanic eruption.

Picture Credit: Carine Ciselet

From the Lujiatun Beds of the Yixian Formation

The pair of beautifully preserved fossils, like so many vertebrate fossils from this part of the world were acquired from farmers.  Many locals supplement their incomes by finding and excavating specimens.  Whilst welcoming the opportunity to be able to study the material, palaeontologists are often frustrated by the lack of information available to them pertaining to the fossil’s location and how it was preserved (taphonomy).  However, it is thought that the fossils herald from the Lujiatun Beds (Yixian Formation) of western Liaoning Province.  These three-dimensional fossils were formed when these dinosaurs were entombed in pyroclastic material created by a volcanic eruption.  Numerous dinosaurs are known from the Lujiatun Beds including the dromaeosaurid Graciliraptor (G. lujiatunensis), the troodontid Mei long, the small tyrannosauroid Dilong paradoxus along with psittacosaurs, neoceratopsians and the ornithopod Jeholosaurus (J. shanyuensis).

Scientists have been able to accurately date the volcanic ash layer to approximately 123 million years ago, which means this diverse dinosaur biota lived during the early Aptian faunal stage of the Early Cretaceous.   The hot, volcanic debris that covered these two dinosaurs may have perfectly preserved most of the skeleton but any evidence of an integumentary covering such as feathers was destroyed as these animals met their fate whilst fast asleep in their burrows.  The resting dinosaurs having been caught up and consumed in a violent pyroclastic flow is the scenario tentatively proposed by the research team in the scientific paper published in PeerJ.

The Two Fossils of Changmiania liaoningensis

Views of the holotype and a referred specimen of Changmiania liaoningensis.

The holotype fossil (A) and a close view of the anterior portion of the holotype (B), with a second referred specimen of Changmiania liaoningensis (C).

Picture Credit: Yang et al (PeerJ)

A Basal Ornithopod

The little dinosaur measured approximately 1.2 metres long, the tail representing fifty percent of the animal’s total body length.  The extremely short neck, consisting of just six cervical vertebrae, the robust forelimbs and stocky shoulder blades suggest that this dinosaur might have dug burrows.  This idea is supported by the position of the fossil specimens and the morphology of the front of the skull, which may have assisted with shovelling dirt aside.  The long hindlimbs and tail indicate that Changmiania was a fast runner, able to avoid trouble whilst away from its underground den.

This is not the first time fossorial behaviour has been inferred for a dinosaur.  For example, in 2007 Everything Dinosaur wrote a short post about another potential burrowing ornithischian, another basal ornithopod that was named Oryctodromeus cubicularis, remains of which come from the sandstones of the Blackleaf Formation of Montana (USA): A Burrowing Dinosaur from Montana.

Changmiania lived at least 10 million years earlier than O. cubicularis.  A phylogenetic analysis places Changmiania liaoningensis as the most basal ornithopod dinosaur known to science.

The scientific paper: “A new basal ornithopod dinosaur from the Lower Cretaceous of China” by Yuqing Yang, Wenhao Wu, Paul-Emile Dieudonné and Pascal Godefroit​ published in PeerJ.

6 09, 2020

An Armoured Dinosaur from British Columbia

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Body Fossils of an Ankylosaurian Dinosaur from British Columbia

A small sandstone block containing the back end of a single, fragmentary dorsal vertebra, a dorsal neural arch and two pieces of rib, probably fossils from one animal, have been identified as the fossilised bones of an armoured dinosaur.  This material, originally collected in 1930, is one of just a handful of dinosaur bones known from the early Late Cretaceous of Canada (Cenomanian faunal stage).  Although fossilised footprints associated with ankylosaurian dinosaurs are known from the area, these are the earliest reported body fossils from the Dunvegan Formation of British Columbia and as such these bones may provide palaeontologists with a new perspective on the transition of dinosaur biotas into the Late Cretaceous of North America.

Fossil Material Identified as Ankylosaurian

Photographs and line drawings of ankylosaurian fossil material.

Sandstone block containing portions of two ankylosaurian dorsal vertebrae and two probable ribs.  Photograph (a) and line drawing (b) lateral view.  Photograph (c) reserve side of block showing two probable ribs and parts of the vertebrae with (d) line drawing.

Picture Credit: Arbour et al (Fossil Record)

Bones Collected in 1930

The specimen was collected by the Canadian geologist Merton Yarwood Williams in 1930 during a geological survey of the area of the “Peace River district”.  Charles M. Sternberg later identified the fossil material as representing an ornithischian dinosaur resembling Camptosaurus.  It was loaned to the Royal Ontario Museum for preparation and study and as part of the research, several members of the scientific team visited the area where the fossil was discovered in an attempt to relocate the original site.  Unfortunately, high river levels prevented an extensive search of the steep sided riverbanks.  The team did find a number of plant fossils and a natural cast of a dinosaur footprint – Tetrapodosaurus, an ichnogenus believed to represent an ankylosaurian.  Dinosaur footprint fossils are associated with this area, many of these tracks are thought to represent armoured dinosaurs.

Details of the Ankylosaurian Vertebrae (British Columbia)

Details of the Ankylosaurian vertebrae (British Columbia).

Right lateral view of isolated neural arch (a), with (b) axial view of the isolated centrum, broken at its approximate mid-length and showing strong constriction, inferring an hour-glass shape for the bone.  Ventral view of the transverse process of the isolated neural arch (c).

Picture Credit: Arbour et al (Fossil Record)

The Dunvegan Formation outcrops in both northern Alberta and British Columbia, it is primarily composed of marine strata and deposits laid down in a near-shore delta environment.  Vertebrate fossils are rare but shark and teleosts (bony fish), fossils have been found, including one remarkable discovery of a bony fish found in a 75 mm diameter oil drill core – Tycheroichthys dunveganensis.

To read about this serendipitous fossil fish discovery: Amazing Fossil Fish Found in Canadian Oil Drill Core.

These fragmentary remains (CMN 59667), are the only body fossils of an ankylosaurian known from British Columbia, although a few dermal scales and ossicles from an outcrop of the Dunvegan Formation in Alberta have been ascribed to an armoured dinosaur.  It is difficult to date the sediments accurately, but the fossils are approximately 99-96 million years old.

What Sort of Ankylosaurian Was It?

CMN 59667 has been identified as ankylosaur material based on a number of traits and characteristics observed in the vertebrae.  Although ankylosaur fossils are known from roughly contemporaneous strata in the United States, these types of dinosaurs are not common components of the associated dinosaur fauna.  The body fossils are too fragmentary to confidently assign them to either a nodosaurid or an ankylosaurid ankylosaur.  The fossils are still highly significant, terrestrial Cenomanian assemblages are rare in North America but those fossils that have been found provide evidence of an important time in our planet’s history when there was a considerable faunal turnover between the end of the Early Cretaceous and the earliest Late Cretaceous.

A Scale Drawing of the Roughly Contemporaneous Animantarx from the Cedar Mountain Formation of Utah (USA)

Animantarx Scale Drawing.

A scale drawing of the armoured dinosaur from Utah – Animantarx ramaljonesi.  This dinosaur speculatively assigned to the Nodosauridae, is roughly contemporaneous with the ankylosaurian from the Dunvegan Formation of British Columbia.

Picture Credit: Everything Dinosaur

The discovery of skeletal fossils from the Pine River demonstrates the potential for the Dunvegan Formation to produce terrestrial vertebrate fossils that may provide important new data on this significant transitional period during the Cretaceous.  The researchers hope that the discovery of more body fossils from this location will help them to make a more specific identification as to what sort of ankylosaurian dinosaur roamed this part of British Columbia.

To read about the discovery of a leptoceratopsid, the first unique dinosaur from British Columbia, that was named and described by two authors of the ankylosaurian scientific paper: A New Leptoceratopsid Ferrisaurus sustutensis from British Columbia.

The scientific paper: “An ankylosaurian dinosaur from the Cenomanian Dunvegan Formation of northeastern British Columbia, Canada” by Victoria M. Arbour, Derek Larson, Matthew Vavrek, Lisa Buckley and David Evans published in the Fossil Record, an open-access journal of the Museum für Naturkunde

4 09, 2020

A New Armoured Dinosaur from China

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Sinankylosaurus zhuchengensis – Late Cretaceous Chinese Ankylosaur

Chinese scientists have described a new species of armoured dinosaur based on a single fossilised bone found at a dig site in the city of Zhucheng in Shandong Province (eastern China).  The fossil, a right ilium, has been identified as typical of the Ankylosauria clade and represents the first evidence found to date of ankylosaurs being present in the Late Cretaceous of that part of eastern China.  The dinosaur has been appropriately named Sinankylosaurus zhuchengensis which translates as “Chinese Ankylosaurus from Zhucheng”.

The Holotype Fossilised Right Ilium (Sinankylosaurus zhuchengensis)

Sinoankylosaurus ilium in (a) ventral and (b) dorsal views. Scale bar = 10 cm.

The fossil ilium bone (holotype specimen) of Sinankylosaurus.  Sinankylosaurus ilium in (a) ventral and (b) dorsal views.  Scale bar = 10 cm.

Picture Credit: China Geological Bulletin

A Significant Hip Bone

The ilium is a broad, plate-like bone located at the top of the hip girdle.  Its shape and size varies considerably depending on the dinosaur genus.  These bones and the placement of the hips can be very helpful to palaeontologists when it comes to identifying different members of the Dinosauria.  For example, most theropods have narrow hips so the distance between the left and right ilia (plural for ilium), is relatively short.  However, there are exceptions, the mainly herbivorous theropods the therizinosaurids have much wider hips.  Numerous sauropods and all thyreophorans (armoured dinosaurs), have very wide hips in relation to their body proportions.  In armoured dinosaurs the distance between the left and right ilia is substantial and in Cretaceous ankylosaurs this bone is very distinctive as it exhibits lateral flaring, providing anchor points for large muscles.

The configuration of the ilium in association with the other hip bones, the ischium and pubis, led to the establishment of two main dinosaur Orders – Saurischia and Ornithischia as proposed by the British palaeontologist Harry Govier Seeley in 1887.  These three bones form the “hip socket” into which the head of the femur (thigh bone) is located.

Classifying Dinosaurs Based on Hip Structure

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

Classifying dinosaurs by the shape of their hip bones.  The configuration and orientation of the hip bones led to the establishment to two main groups of dinosaurs in the 19th Century.

Picture Credit: Everything Dinosaur

From the Xingezhuang Formation

The ilium was found about a decade ago.  It comes from the Xingezhuang Formation of the Upper Cretaceous Wangshi Group.  The strata have proved difficult to date but most palaeontologists suggest that this formation is between 77 to 73 million years old (middle to late Campanian faunal stage).  With so very little fossil material to go on, the scientists have used the roughly contemporaneous ankylosaurid Pinacosaurus (P. grangeri) which heralds from the Djadokhta Formation of Mongolia, as a reference and to permit a life reconstruction of an ankylosaurid to be used in media releases.

A Life Reconstruction of Pinacosaurus – Sinankylosaurus May Have Been Similar

Life reconstruction Pinacosaurus grangeri.

Pinacosaurus life reconstruction.  Sinankylosaurus zhuchengensis may have been similar.

Picture Credit: Zhao Chuang (PNSO)

Sinankylosaurus is estimated to have measured around 5 metres in length and it may have weighed around 2 tonnes.

East Meets West

The discovery of a new dinosaur species adds to the diversity of dinosaurs associated with the Upper Cretaceous deposits of the Wangshi Group and also demonstrates the similarity between the dinosaurian faunas of eastern Asia and western North America in the Late Cretaceous.

For example, dinosaur fossils from the Xingezhuang Formation include hadrosaurs such as Shantungosaurus, ceratopsids such as Sinoceratops, tyrannosaurs and now an ankylosaurid.  This biota is similar to the dinosaur fauna associated with Campanian-aged deposits found in southern Canada and the USA.

3 09, 2020

Calculating the Size of Megalodon

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Measuring Megalodon

Researchers from the University of Bristol in collaboration with colleagues from the University of Swansea have undertaken a detailed analysis using mathematical models and comparisons with extant shark species to provide an answer to the question – just how big was “megalodon”?  Writing in the academic journal “Scientific Reports”, the scientists set about trying to calculate the overall size and the body part dimensions of the giant prehistoric shark, an animal that is believed to be the largest macropredatory shark that has ever existed.

As a shark and therefore with a skeleton made from cartilage and not bone, body fossils are limited to the triangular teeth and to rare calcified vertebrae.  In the absence of extensive fossil material, it is very difficult for scientists to estimate just how big this predator was.  The problem is compounded when an extinct animal is considerably larger than the largest living macropredatory shark, the Great White (Carcharodon carcharias).

A Set of Jaws – This Prehistoric Shark is Known Mainly From Fossilised Teeth

Megalodon jaws.

A set of jaws from a “megalodon”  The lack of body fossils limits the ability of scientists to estimate body size.

Referencing O. megalodon

The research team which includes Professor Michael Benton (School of Earth Sciences, University of Bristol), use the species moniker Otodus megalodon in the scientific paper.  Readers of this blog may note, that “megalodon” is listed as Carcharocles megalodon in many of our articles and indeed elsewhere in other scientific literature.  When it comes to this iconic fish, a creature which recently starred in its own movie, “The Meg”, which was released in 2018 and grossed more than $500 million dollars in cinemas, it is not only it size and body proportions that cause debate.  Its taxonomic placement is also controversial.  Most scientists consider “megalodon” to be a member of the Lamniformes Order – the mackerel sharks, furthermore, part of the Otodontidae family, the “megatoothed sharks”, but the phylogeny of the species remains uncertain.

Most studies of “megalodon” rely on comparisons with Carcharodon carcharias as the teeth morphology is similar, but in this research, the scientists estimated the body size and proportions of the extinct animal by comparing it to Great Whites and four other types of mackerel shark – namely:

  • The Porbeagle shark (Lamna nasus) which is present in British waters.
  • The Salmon shark (Lamna ditropis) from the North Pacific.
  • The Shortfin Mako (Isurus oxyrinchus) which has a global distribution including British waters but it is increasingly rare.
  • The Longfin Mako (Isurus paucus) which is found in both temperate and tropical waters and like the closely related Shortfin Mako it is becoming increasingly rare.

This study marks the first quantitative estimate of O. megalodon specific body-part dimensions, beyond its overall body size.

Measuring the “Megalodon”

Measuring megalodon.

Silhouette models visualising Otodus megalodon body dimensions based on the extrapolations at different total lengths.  Silhouette (a)  ~ 16 m, (b)  ~ 3 m and (c)  ~ 8 m.  Life reconstruction of O. megalodon with 1.65 metre tall diver for scale.

Picture Credit: Cooper et al (Scientific Reports)

A Giant Prehistoric Shark

The Hollywood “megalodon” was around twenty-three metres in length.  The scientific paper does not suggest that this shark was that big, but their results suggest that a sixteen-metre-long animal had a head around 4.65 metres in length, that’s about the length of a Range Rover Discovery 4×4 vehicle.  The tail fin was estimated to have been approximately 3.85 metres high and this study suggests that the dorsal fin was around 1.62 metres tall.

This research is not likely to influence movie makers and film directors as they plan a sequel to the 2018 release, but the reconstruction of this giant fish,  represents a significant step towards a better understanding of the physiology of this monster.  In addition, having a better understanding of its body proportions and overall size will allow scientists to infer how much food these animals had to consume and other factors that may have facilitated its ultimate demise and extinction.

The Hollywood Movie was Based on the Novel by Steve Alten

"Meg" front cover image.

Exciting and thrilling adventure story based on “Megalodon”.  This research suggests that this giant prehistoric shark would have dwarfed a surfer.

The scientific paper: Paper: “Body dimensions of the extinct giant shark Otodus megalodon: a 2D reconstruction” by J. A. Cooper, C. Pimiento, H. G. Ferrón, and M. J. Benton published in Scientific Reports.

2 09, 2020

How to Estimate the Weight of a Dinosaur?

By | September 2nd, 2020|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Dinosaurs – A Weighty Problem

A weighty problem for palaeontologists studying non-avian dinosaurs is how to go about estimating the body mass of these long extinct creatures.  Working out how to weigh a dinosaur is compounded when it comes to the Sauropodomorpha, as there are no living analogies for scientists to use as a reference, nothing remotely like an Argentinosaurus or an Apatosaurus alive today to provide a guide when it comes to the calculations.  For those armoured dinosaurs too, finding a modern day analogy can be tricky.  As for the Theropoda, attempting to scale up Tyrannosaurus rex based on the largest living theropod today, an ostrich (Struthio camelus), has obvious drawbacks.

Writing in the academic journal “Biological Reviews”, researchers from the Royal Ontario Museum and the University of New England have helped to put the current methods used into context.

The Diverse Non-avian Dinosaurs – Estimating the Weight of Long Extinct Animals is a Challenge

The diverse Dinosauria.

The Dinosauria consists of a huge range of different sized animals with different body plans.

Picture Credit: Everything Dinosaur

Two Main Methods of Weighing a Dinosaur

The debate about just how heavy dinosaurs were has raged for more than 150 years.  A range of different methods are used to estimate body mass, but these can be split into two broad categories.

  1.  Volumetric Density (VD) – which involves calculating a body weight based on a three-dimensional reconstruction of the animal – working from the skeleton outwards.
  2.  Extant Scaling (ES) – measuring the size of limb bones in living animals, most usually the circumference of the femur (thigh bone) or the humerus (upper arm bone) and then scaling up the body weight based on measurements from the same bones in the skeleton of the dinosaur.

With no definitive non-avian dinosaur bodyweights known, there has been considerable debate as to which method was likely to produce the most robust and trustworthy results.  Lead author of the study, Dr Nicolás Campione (University of New England), explained that the research team created an extensive database of dinosaur body weight estimates going back to 1905, the year when the most famous dinosaur of all T. rex was scientifically described.  The scientists found that once scaling (ES) and reconstruction methods (VD), were compared, most estimates agreed.  Apparent differences are the exception, not the rule.

Co-author of the study, Dr David Evans (Royal Ontario Museum), explained that these findings should give authors confidence, it does not seem to matter too much which calculation method is used, as these results indicate that mass estimates are largely consistent between the two approaches.  The femur/humerus scaling method, which relies on relationships obtained directly from living animals of known body mass, provides a measure of accuracy, but often of low precision.  In contrast, reconstructions that consider the whole skeleton provide precision, but of unknown accuracy.  This is because reconstructions depend on our own subjective ideas about what extinct animals looked like, which have changed considerably overtime, a review of Iguanodon illustrations demonstrates this point succinctly.

Iguanodon’s Body Plan has Been Revised Many Times

Iguanodon - changing scientific interpretations.

The changing body plan of Iguanodon.

Picture Credit: Everything Dinosaur

Why Does Knowing the Body Weight of a Dinosaur Matter?

Having an estimate of a dinosaur’s body weight is important.  Body size, in particular the body mass, influences all aspects of the animal’s life, including their diet, ability to maintain body temperature, reproduction and locomotion.

Dr Campione stated:

“If we know that we have a good estimate of a dinosaur’s body mass, then we have a firm foundation from which to study and understand their life retrospectively.”

The researchers recommend that future work seeking to estimate the sizes of non-avian dinosaurs, and other extinct animals, need to better-integrate the extant scaling and volumetric density methods as both approaches have been revealed to be more complementary than antagonistic.

Everything Dinosaur acknowledges the assistance of a media release from the Royal Ontario Museum in the compilation of this article.

The scientific paper: “The accuracy and precision of body mass estimation in non-avian dinosaurs” by Nicolás E. Campione and David C. Evans published in Biological Reviews.

30 08, 2020

Ancient Crocodile Attacked Ground Sloths

By | August 30th, 2020|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Juvenile Purussaurus Attacked Ground Sloth

The giant prehistoric caiman Purussaurus is regarded as one of the largest crocodilians to have ever lived.  How big this predator of the wetlands of South America during the Miocene actually was, remains open to debate.  It is known mainly through skull material, (the largest measuring 1.45 metres in length) and isolated teeth.  It is one of several types of crocodiles associated with the Pebas Mega-Wetland System from the north-western side of the continent.  Evidence of Purussaurus interaction with prey is limited, confined to a scarred and dented turtle shell, documenting a failed attack by an adult Purussaurus.  However, scientists have reported the discovery of the lower leg bone of a ground sloth that bears the tell-tale tooth marks and scratches of an attack from a Purussaurus (P. neivensis).  The sloth identified as the genus Pseudoprepotherium very probably did not survive the encounter with a four-metre-long caiman.

A Life Reconstruction of the Purussaurus Attack

Ground sloth attacked by Purussaurus.

A ground sloth (Pseudoprepotherium) attacked by the giant South American caiman Purussaurus.  In total 46 toothmarks were identified on the 13 million-year-old tibia bone from the ground sloth.

Picture Credit: Jorge A. González

Attacked by a Juvenile Purussaurus

Thirteen million years ago, South America was an island continent.  There was no isthmus joining the landmass to North America and therefore no opportunity for placental carnivores (Order Carnivora), to enter South America.  There were terrestrial predators, such as pouched mammals from the marsupial lineage (sparassodonts) and three-metre-high terror birds (phorusrhacids).  Competing with these creatures for the title of most feared predator was the prehistoric caiman Purussaurus neivensis and its close relatives.  Writing in “Biology Letters”, palaeontologist Rodolfo Salas-Gismondi from Cayetano Heredia University (Peru), along with co-author François Pujos conclude that the bitemarks on a tibia found during field work in north-eastern Peru represent predation by a four-metre-long, juvenile Purussaurus.

The Location of the Fossil Find and Views of the Damaged Tibia

Purussaurus attacked ground sloth.

The location of the fossil tibia find in north-eastern Peru.  Close-up views of the toothmarks on the tibia and line drawings.

Picture Credit: Salas-Gismondi and François Pujos (Biology Letters)

The picture (above), shows the  Pebas Mega-Wetland System around 13 million years ago (a).  Na069 represents the bonebed where the tibia was found and (b) shows this bonebed location on the Napo River in north-eastern Peru.   The left tibia of the ground sloth is shown in anterior (c i) and posterior (c ii) views with accompanying line drawings.  Photographs (d-f) highlight individual toothmarks and punctures.  The red dots map the bitemarks.

Extant and Extinct Crocodilian Skulls Compared Along with Purussaurus Teeth and Damaged Turtle Shell 

Crocodilian skulls and bitemark damage.

The skull of an adult black caiman compared to a juvenile Purussaurus neivensis, the bite-marked tibia and the skull of a fully grown P. neivensis along with turtle shell showing bitemark.

Picture Credit: Salas-Gismondi and François Pujos (Biology Letters)

The picture (above) shows dorsal views of an adult extant black caiman (Melanosuchus niger) skull (a) compared with the skull of a juvenile Purussaurus neivensis (b), facing the damaged ground sloth tibia.  The skull of an adult P. neivensis (c) and teeth (d).  The shell of the prehistoric turtle Podocnemis with a portion of the carapace missing attributed to a bite from a huge Purussaurus brasiliensis (tip of jaw in line drawing).

A Substantial Meal for a 4-metre Crocodilian

The interpretation of the damaged tibia as evidence of predation from Purussaurus neivensis provides a rare insight into prehistoric crocodilian/prey behaviour.  It suggests that prior to reaching adult size, young individuals fed upon terrestrial mammals about the size of a capybara.  The ground sloth is estimated to have weighed around 78 kilograms that’s the about the same as an adult human male.  If a young Purussaurus could take down an sloth weighing as much as a man, it speaks volumes for that person’s chances if they ever would have met a fully grown Purussaurus.

To read an article commenting on contenders for the largest crocodile known to science: Which was the Largest Crocodilian of All Time?

Ancient Purussaurus from Venezuela had unique adaptations to help it move: Ancient Crocodilian Evolved Unique Specialisations Due to its Size.

Prehistoric crocodilians from Peru: Peruvian Paradise for Prehistoric Crocodiles.

The scientific paper: “Predation of the giant Miocene caiman Purussaurus on a mylodontid ground sloth in the wetlands of proto-Amazonia” by François Pujos and Rodolfo Salas-Gismondi published in Biology Letters.

29 08, 2020

Have You Heard About the Evolution of the Mammalian Middle Ear?

By | August 29th, 2020|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Newly Described Multituberculate Mammal Provides Clues to Middle Ear Evolution

A team of international scientists from the Chinese Academy of Sciences, the American Museum of Natural History (New York) and the Beipiao Pterosaur Museum of China, have described a new species of multituberculate mammal that once roamed and climbed in the forests of north-eastern China during the Early Cretaceous.  The small creature has been named Sinobaatar pani and its delicate middle ear bones have been preserved providing researchers with an opportunity to study the evolutionary development of hearing.

A Life Reconstruction of the Small Multituberculate Mammal S. pani

 A life reconstruction of Sinobaatar pani.

Newly described multituberculate mammal provides clues to middle ear evolution.  A life reconstruction of Sinobaatar pani.

Picture Credit: Institute of Vertebrate Palaeontology and Palaeoanthropology (IVPP)

How do Mammals Hear?

The terrestrial placental mammal ear can be divided into three sections:

  1. Outer ear – collects and directs sound via the ear flap (pinna) and the outer ear canal which ends in the eardrum (tympanic membrane).
  2. Middle ear – which filters and amplifies sound waves directing them to the inner ear.  The middle ear contains three, delicate and tiny bones (ossicles), the anvil, hammer and the stapes (incus, malleus and stirrup).
  3. Inner ear – consisting of the cochlea (organ for hearing) and the vestibular system (associated with balance).

The Inner Bones of a Model Mammal

Diagram of the middle ear of a modern mammal.

The three middle ear bones of a modern mammal.  The three tiny bones are highlighted, these transfer vibrations from the eardrum to the inner ear, where the sound waves are changed into electrical signals by the cochlea which are then deciphered by the brain.

Picture Credit: Everything Dinosaur

It is the inner ear bones that act as a bridge between the eardrum and the oval window which is the opening to inner ear.  The cochlea, which is a hollow, spiral shaped bone transduces the sound waves into electrical signals (neural impulses), that are deciphered by the brain.

Scientists believe that bones that were once part of the reptilian jaw slowly evolved into the three bones that are now found in the middle ear.  A joint research team led by Dr Mao Fangyuan from the Institute of Vertebrate Palaeontology and Palaeoanthropology (IVPP) of the Chinese Academy of Sciences and Professor Meng Jin from the American Museum of Natural History were able to model the delicate middle ear bones of S. pani by using computerised tomography to access and view the fossils whilst they were still surrounded by matrix.  The powerful, rock-penetrating X-rays allowed the scientists to construct three-dimensional computer models of the malleus, incus and the stapes and to study their shape.

The images generated, permitted the comparing of the tiny inner ear bones of the Early Cretaceous multituberculate with the embryos of different types of living mammal (placental, marsupial and monotreme).

Dr Mao explained that her colleagues were able to examine and assess the ancestral phenotype of the mammalian middle ear.  The researchers recognised that the three main Mesozoic mammalian groups (multituberculates, eutriconodontans and symmetrodontans) share a similar middle ear structure between the incus and malleus, which they termed the “braced hinge joint”.  Although they acknowledged that the middle ear may have evolved independently in several mammalian groups, they proposed that the braced hinge joint could represent a critical feature of the ancestral phenotype of the mammalian middle ear.

The Evolution of Mammalian Hearing

Evolution of the mammalian middle ear.

The evolution of the mammalian middle ear.  The skull and jaw of an early synapsid (pelycosaur) compared to the skull and jaw of a later synapsid, the evolution of the three middle ear bones.

Picture Credit: Everything Dinosaur

Dr Mao commented:

“There are two basic patterns of the middle ear in living mammals, represented by monotremes and therians [placentals and marsupials], respectively.  In the former, the middle ear is characterised by an “abutting contact” between the incus and malleus, which is distinct from the one in therian mammals where the incus-malleus articulation is saddle-shaped.”

The abutting pattern in monotremes and the saddle-shaped joint in therians may well be derived from the braced hinge joint linking the incus and malleus as observed in Mesozoic mammals.  At the very least, these fossil forms have narrowed the morphological gap between the middle ear of protomammals, formed by the postdentary bones lodged in the lower jaw, to the middle ear of extant mammals.  The researchers proposed that the surangular bone, which is another postdentary bone in protomammals, persisted in Mesozoic mammals; its fate in living mammals remains uncertain.

Writing in the National Science Review, the researchers demonstrate that middle ear morphologies in Mesozoic mammals represent different evolutionary stages with Sinobaatar showing an advanced inner ear configuration.  Furthermore, the evolutionary changes recorded in the Mesozoic mammals are largely consistent with the way the middle ear bones develop as living mammals grow, supporting the relationship between evolution and development.

The Holotype of S. pani and Three-dimensional Skull and Teeth Images

Sinobaatar pani holotype material.

The holotype specimen of Sinobaatar pani (BPMC 0051) in the matrix (A) the black rectangle shows the area that has been CT-rendered to show the three-dimensional skull (B).  Left upper dentition in (C) lingual and (D) occlusal views.

Picture Credit: Institute of Vertebrate Palaeontology and Palaeoanthropology (IVPP)

Everything Dinosaur acknowledges the assistance of a press release from the Chinese Academy of Sciences in the compilation of this article.

The scientific paper: “Exploring ancestral phenotypes and evolutionary development of the mammalian middle ear based on Early Cretaceous Jehol mammals” by Fangyuan Mao, Cunyu Liu, Morgan Hill Chase, Andrew K Smith and Jin Meng published in National Science Review.

27 08, 2020

Baby Sauropods had Rhino-like Horns

By | August 27th, 2020|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Horned Baby Dinosaurs But Not a Ceratopsian in Sight!

A team of international researchers have published a new scientific paper that reports on the discovery of a beautifully preserved embryo of a dinosaur.  The fossil specimen representing a titanosaur, that lived around 80 million years ago, has permitted palaeontologists to demonstrate that these herbivores had stereoscopic vision, just like most of the carnivorous dinosaurs that would have hunted them.  Furthermore, the embryonic skull has revealed that these sauropods had small horns on the front of the face, which they later lost as they grew up.

A Close-up View of the Embryonic Titanosaur Skull

A view of the embryonic skull of the titanosaur

A close-up view showing the embryonic titanosaur articulated skull preserved inside the dinosaur egg.

Picture Credit: The University of Manchester

An Amazing Fossil Discovery

The research team, which included Dr John Nudds (Manchester University), state that this is the most complete and articulate skull known from any titanosaur, a group of temporally and geographically diverse sauropods, members of which evolved into some of the largest land animals that ever existed.  The egg fossil was discovered in southern Argentina (Patagonia) and heralds from strata laid down during the Cretaceous (Campanian faunal stage of the Late Cretaceous).

A Life Reconstruction of a Group of South American Titanosaurs

Titanosaurs illustrated.

An illustration of a group of Titanosaurs.  New study suggests that these herbivores had stereoscopic vision and the babies had a facial horn to help them break out of their egg.

Picture Credit: Marcos Paulo

It was imperative the egg was repatriated to Argentina however as it is illegal to permanently remove fossils from the country.

Commenting on the significance of the fossil discovery, Dr John Nudds (Manchester University) stated:

“The preservation of embryonic dinosaurs preserved inside their eggs is extremely rare.  Imagine the huge sauropods from Jurassic Park and consider that the tiny skulls of their babies, still inside their eggs, are just a couple of centimetres long.  We were able to reconstruct the embryonic skull prior to hatching.  The embryos possessed a specialised craniofacial anatomy that precedes the post-natal transformation of the skull in adult sauropods.  Part of the skull of these embryonic sauropods was extended into an elongated snout or horn, so that they possessed a peculiarly shaped face.”

Revising Opinions About Baby Dinosaur Anatomy

The analysis of the fossil specimen allowed the research team to revise opinions on how babies of these huge dinosaur might hatch and to test previously held ideas about sauropodomorph reproduction.  The elongated facial horn may have been used as an “egg tooth” to help the babies to break out of their eggs.

New Study Tests Ideas about Sauropodomorph Reproduction

Fragment of dinosaur eggshell (A) and the embryonic titanosaur skull (B).

Eggshell fragment (A) and the skull of the embryonic dinosaur (B).  Note scale bar = 2 cm.

Picture Credit: The University of Manchester

The paper has been published today in the academic journal “Current Biology”.  The fossilised bones of the embryo were revealed by dissolving the matrix using an acid preparation.  The researchers were able to perform a virtual dissection of the fossil material by bombarding the specimen with powerful X-rays to build up a three-dimensional image.   The European Synchrotron Radiation Facility (ESRF) at Grenoble was employed for this purpose.

Dinosaur embryology remains one of the least explored and poorly understood areas of research when it comes to the Dinosauria.   Argentina has provided palaeontologists with evidence of titanosaur nesting sites and embryos before, most famously the nest sites discovered in northern Patagonia associated with Saltasaurus loricatus that were studied by the famous Argentinian palaeontologist José Bonaparte.   Saltasaurus was named and described in 1980, the first titanosaur to be named from South America.  Since then, many more genera have been erected including Argentinosaurus, Andesaurus, Barrosasaurus, Bonatitan, Dreadnoughtus and Futalognkosaurus.

However, this is the first time a fully intact embryo has been studied.  Other fossilised eggs are also known from this site, the scientists hope to repeat their work with other specimens and are optimistic that some of the eggs might even retain the preserved remains of dinosaur skin.

The scientific paper, “Specialized Craniofacial Anatomy of a Titanosaurian Embryo from Argentina” is published in Current Biology.  The lead author on the paper is Martin Kundrat, Evolutionary Biodiversity Research Group Pavol Jozef Šafárik University.

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