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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.

22 06, 2017

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

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

New Specimens of Extinct Crocodylian Baru Described

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

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

A Reconstruction of the Large Prehistoric Crocodile Baru wickeni

The ancient Australian crocodile Baru wickeni

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

Picture Credit: Paul Willis

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

Baru- Formidable Ancient Aussie Croc

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

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

The Significance of the Scientific Paper

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

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

B. wickeni skull.

A skull of the prehistoric crocodile Baru wickeni.

Picture Credit: Adam Yates

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

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

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

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

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

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

13 06, 2017

Watch the Birdie (Enantiornithine in Amber)

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

Nearly Complete Baby Bird Preserved in Amber

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

Enantiornithine Hatchling Preserved in Burmese Amber

Baby Enantiornithine bird trapped in amber.

Baby bird preserved in amber.

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

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

A Very Young Bird

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

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

Fossil bird trapped in amber.

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

Picture Credit: Ryan McKellar (Royal Saskatchewan Museum)

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

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

Nicknamed “Belone”

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

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

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

The Enantiornithine Hind Leg

Enantiornithine hindlimb

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

Picture Credit: Ming Bai

A Precocial Bird

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

A Close View of One of the Claws

Enantiornithine claw.

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

Picture Credit: Ming Bai

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

To read more: Bird Wing Trapped In Amber

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

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

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

31 05, 2017

Oldest Swinger in Town – Torrejonia wilsoni

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

New Mexico’s Oldest Primate Torrejonia wilsoni

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

The Torrejonia wilsoni Fossil Material Indicates an Arboreal Existence

Torrejonia fossil material (T. wilsoni).

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

Picture Credit: Royal Society Open Science

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

Box a = elements from the skull

Box b = parts of the jaws

Box c = arm bones

Box d = the shoulder blade (scapula- fragmentary)

Box e = elements from the astragalus (ankle)

Box f = leg bones

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

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

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

Illustrations of Typical Plesiadapiforms

Illustrations of plesiadapiforms.

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

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

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

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

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

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

19 05, 2017

Say it with Flowers from the Danian to be Exact

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

Flowering After a Disaster – Oldest Buckthorn Fossilised Flowers

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

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

Two Buckthorn flower fossils.

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

Picture Credit: Nathan Jud/Cornell University (USA)

Flowering After the Fern Spike

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

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

The “Fern Spike” – Plotted Against Geological Time

Plotting the Danian fern spike.

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

Graph Credit: Everything Dinosaur

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

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

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

The Origins of the Rhamnaceae Family

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

Dr Jud commented:

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

Fossilised Leaves from the Salamanca Formation (Buckthorn Family)

Views of Buckthorn leaves (Danian faunal stage).

Buckthorn fossils (leaves).

Picture Credit: Nathan Jud/Cornell University and PLOS ONE

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

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

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

In conclusion, Dr Jud stated:

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

30 04, 2017

DNA from Ancient Hominins Discovered in Cave Sediments

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

DNA from Cave Sediments Reveals Ancient Human Occupants

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

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

Searching for evidence of ancient hominin DNA.

Excavations at the site of El Sidrón, Spain.

Picture Credit: El Sidrón research team

The Secrets of Cave Soils and Sediments

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

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

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

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

Entrance to the Archaeological Site of Vindija Cave, Croatia

Searching for traces of ancient human DNA.

Entrance to the archaeological site of Vindija Cave, Croatia.

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

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

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

DNA analysis identifies cave inhabitants.

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

Picture Credit: Journal Science

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

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

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

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

A New, Important Tool for Palaeoanthropology

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

A Sample Ready for Testing

Testing cave sediments for ancient human DNA.

A cave sediment sample is prepared for DNA testing.

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

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

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

23 03, 2017

Root and Branch Reform for the Dinosaur Family Tree

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

Dinosaur Family Tree Given a Hefty Shake

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

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

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

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

We have tried to summarise the key findings as:

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

The Traditional Dinosaur Family Tree Compared to the New Model

Comparing different views on the dinosaur family tree.

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

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

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

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

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

Hypercarnivory (Meat-eating) Evolved Twice

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

Herrerasaurus Gets a New Status within the Revised Dinosaur Family Tree

An illustration of a Triassic dinosaur Herrerasaurus.

Herrerasaurus Illustration

Science Itself Evolves

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

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

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

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

A Phylogenetic Relationship of Early Dinosaurs Plotted Against Geological Time

Re-drawing the dinosaur family tree.

The phylogenetic relationships between early dinosaurs.

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

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

Not “Throwing the Baby Out with the Bathwater”

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

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

Footnote

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

Classifying the Dinosauria by Their Hip Bones

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

Classifying dinosaurs by the shape of their hip bones.

Picture Credit: Everything Dinosaur

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

22 03, 2017

Newly Described Silurian Fossil Honours Sir David Attenborough

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

Fossil Discovery Named in Honour of Sir David Attenborough’s 90th Birthday

Sir David Attenborough has been honoured by an international team of scientists who have named a newly described Silurian Arthropod after the veteran broadcaster and naturalist.  Sir David has had a number of new species named in his honour, this 430 million-year-old, distant relative of today’s crabs and lobsters joins a long list of flora and fauna that includes wild flowers and a Jurassic Pliosaur (Attenborosaurus conybeari).

To read an article about a kitten-sized marsupial lion named after Sir David: Attenborough’s New Kitty”

Honouring Sir David Attenborough – Cascolus ravitis

An image (computer generated) of the Silurian Arthropod Cascolus ravitis.

A computer generated image of the newly described Silurian Arthropod Cascolus ravitis.

Picture Credit: Professor David Siveter et al

Sir David grew up in Leicestershire, he and his family lived on the campus of the former University College Leicester, where his father was the principal.  As a boy, Sir David often explored the exposed Jurassic outcrops, near to his Leicester home hunting for fossils.  His love of the local countryside and the animals and plants that surrounded his home, fuelled his passion to become a scientist.

Three-Dimensional Arthropod Fossil

The fossil specimen, which measures less than ten millimetres long, is described as “exceptionally well-preserved in three-dimensions”.  The researchers, which include scientists from Imperial College (London), Oxford University and Yale (United States), as well as Leicester University, have been able to identify the exoskeleton and other parts of the animal, such as the delicate antennae, legs and the compound eyes.  It has been assigned to the Crustacea sub-phylum and joins a remarkable fossil assemblage representing a marine biota preserved when ash from a volcano covered an ancient underwater ecosystem.  The actual location of the fossil site is a closely guarded secret, the site can be found in the county of Herefordshire, close to the Welsh border.  At this location, the limestone rock sequence is interrupted by a fine-grained bedding plane that represents ash from a volcanic eruption that smothered the seabed.  The ash buried all the creatures in and around the seafloor at the time, creating a unique opportunity for palaeontologists to study this ancient habitat.

Professor David Siveter (Department of Geology, Leicester University), commented:

“Such a well-preserved fossil is exciting, and this particular one is a unique example of its kind in the fossil record, and so we can establish it as a new species of a new genus.”

Cascolus ravitis

The genus name is derived from “castrum” meaning stronghold and “colus” which translates from the Old English as “dwelling in”, terms from which the surname Attenborough is derived.  The species name is a combination of “Ratae”, the Roman name for Leicester, “vita” which means life and “commeatis” a messenger.

Sir David Attenborough Receiving a High-Resolution Image of the Fossil Named in His Honour

Sir David Attenborough receiving a copy of the high resolution image of Cascolus ravitis

Sir David Attenborough receiving a high-resolution image of the newly described Silurian fossil.

Picture Credit: Leicester University

Left to right: Derek Siveter, (University of Oxford), Sir David Attenborough, Professor Paul Boyle, President and Vice-Chancellor of University of Leicester and David Siveter, University of Leicester.

Speaking about his latest honour, the nonagenarian, who will be celebrating his 91st birthday in a few weeks’ time, stated:

“The biggest compliment that a biologist or palaeontologist can pay to another one is to name a fossil in his honour and I take this as a very great compliment.  I was once a scientist so I’m very honoured and flattered that the Professor should say such nice things about me now.”

To read about other fossil discoveries from the Herefordshire site: The Kite Runner from the Silurian of England

Prehistoric marine parasites: Prehistoric Parasites from the Silurian

Sir David Attenborough has had a Genus of Jurassic Pliosaur Named in His Honour

Attenborosaurus conybeari

Named in honour of Sir David Attenborough – Attenborosaurus

Picture Credit: Everything Dinosaur

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

The research is published in the journal Proceedings of the Royal Society B (Biology).

19 03, 2017

Dinosaurs Learn to Stand on Their Two Feet

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

New Theory as to Why Bipedalism Evolved in the Dinosauria

Iconic dinosaurs such as Tyrannosaurus rex, Velociraptor, Coelophysis and Carnotaurus were all bipeds.  That is, they evolved the ability to walk on their hind legs.  Bipedalism is a trait that seems to have evolved early in history of the Dinosauria and it is a characteristic that is widespread amongst both lizard-hipped and bird-hipped forms.  It had been suggested that bipedalism arose in the ancestors of dinosaurs, to allow the forelimbs to be freed from a locomotive role, allowing them to have other uses, primarily to seize and grasp prey.  However, a team of scientists from the Department of Biological Sciences at the University of Alberta (Canada), have put forward a new theory to explain why some dinosaurs stood on two feet instead of four.  The ancestors of the dinosaurs had a “need for speed”!

The Basal Dinosauriform Marasuchus (M. lilloensis) is Typical of a Bipedal Ancestor of the Dinosauria

The basal dinosauriform Marasuchus from the Late Triassic of Argentina

The basal dinosauriform archosaur Marasuchus of the Middle Triassic. A potential ancestor of the Dinosauria.

 

Picture Credit: Pterosauriablog (author Taylor Reints)

The picture above shows the crow-sized Marasuchus, fossils of which come from the La Rioja Province (north-eastern Argentina), specifically from the Chañares Formation.  This fast running, bipedal reptile lived some 242 – 235 million years ago and the University of Alberta researchers argue that the presence of big muscles (the caudofemoralis), associated with the back of the legs and tail were central to driving the evolution of bipedalism amongst the archosaurs that were to eventually lead to the evolution of the dinosaurs.

From All Fours to Just Two Legs

Publishing in the academic periodical “The Journal of Theoretical Biology” lead author, Scott Persons and is co-worker Professor Phil Currie, argue that basal dinosauriforms were essentially quadrupeds but they evolved to stand upright, a characteristic that was passed onto their descendants the dinosaurs.

The scientists challenge the idea that bipedalism came about in order to help with the seizing of prey.

Persons stated:

“While that works for some of the very, very early dinosaurs, which were certainly carnivorous, you see a bunch of herbivorous dinosaurs evolve later on and a good many of those groups actually keep their bipedal stance, which is a little strange.”

Big Muscles in the Tail

The researchers argue, that strong muscles at the base of the tail helped to power the hind legs of these prototype dinosaurs.  This allowed them to run faster and for longer.  Hind legs evolved to become longer, whilst the forelimbs became shorter to reduce body weight and to improve balance and agility.  Some of these proto-dinosaurs gave up quadrupedalism entirely.   However, as all young dinosaur fans will happily tell you, there were lots of four-legged dinosaurs, examples being Triceratops, Stegosaurus and Diplodocus.  These dinosaurs were herbivores, they evolved heavy defensive weapons, horns and armour which meant that a faster, cursorial lifestyle was sacrificed.  As plant-eaters, they evolved ever larger stomachs and digestive tracts to help them process the tough plant material they ate, bigger guts also led to a reversion back to being a quadruped.

Palaeontologist Scott Persons added:

“In the groups where speed was no longer a concern, they often went back to being a quadruped”

A Rearing Diplodocus – A Four-Legged Dinosaur

CollectA Rearing Diplodocus.

A rearing Diplodocus!

Picture Credit: Everything Dinosaur

If you take the lizard-hipped, Sauropoda for instance, these herbivores evolved into a myriad of forms, but they all had the same basic body plan and there was a trend towards gigantism within this infraorder.  However, it has been suggested that those strong, muscular tails and powerful back legs enabled these dinosaurs to rear up to feed higher up in the vegetative canopy.  It has been suggested that baby Sauropods may have retained the ability to run on their hind legs, probably to help them escape predators.

To read an article about proposed bipedalism in juvenile Sauropods: Facultative Bipedalism in Young Sauropods

The powerful caudofemoralis muscle provides a greater source of propulsion to the back legs and it is the presence of this tail muscle that may have given the impetus to developing a two-legged stance.

Modern Lizards Provide a Clue

Modern facultatively bipedal lizards offer an analog for the first stages in the evolution of dinosaurian bipedalism.   In biology, the term facultative refers to the ability of many organisms to do things by choice rather than by obligation.  Facultatively bipedal lizards may spend most of the time on all fours, but when the need arises, such as to escape danger, these reptiles can revert to a bipedal stance.  An example of a living facultative biped lizard is the Australian frilled lizard (Chlamydosaurus kingii).

The Australian Frilled Lizard – An Example of a Living Reptilian Facultative Biped

Australian Frilled Lizard

The Australian frilled lizard – a facultative biped.

Why Don’t Fast Running Mammals Run on Two Legs?

Biomechanically, running on four legs is more efficient than running on two legs.  However, the University of Alberta researchers concluded that the behaviour of synapsid reptiles, distant ancestors of today’s fast running horses, cats, camels, and grey hounds, during the Permian, may explain the lack of bipeds amongst the Mammalia.

In the Permian geological period, it seems some animals started losing the reptilian trait of a strong leg-powering tail muscle.  Around that time, many creatures were becoming burrowers, (adapting to a fossorial lifestyle), so they needed strong front limbs for digging.  Big back legs and a long, powerful tail would have made it tough to manoeuvre in the confines of a burrow, as well as making it easier for a pursuing predator to snatch them by their tail.  The scientists postulate that living underground may have helped those proto-mammals survive the Permian mass extinction.  Their descendants would have evolved to run fast, but without the tail muscles that would have caused them to stand upright.

Commenting on the biological merits of Tetrapods evolving to favour one set of legs for running Scott Persons stated:

“That’s a really funny and strange adaptation.  Why would you choose to use just one set of limbs to help you run away when you’re most desperate?  And the answer has to do with that great big tail muscle [caudofemoralis].  It effectively sort of overpowers the back legs relative to the front legs.  What the lizards are effectively doing is popping a wheelie as they speed off.”

That cursorial advantage explains the relative abundance of cursorial facultative bipeds and obligate bipeds among fossil diapsids and the relative scarcity of either amongst the Mammalia and their close relatives.  Having lost their caudofemoralis in the Permian, perhaps in the context of adapting to a fossorial lifestyle, the mammalian line has been disinclined towards bipedalism, but, having never lost the caudofemoralis of their ancestors, the basal dinosauriforms and their relatives were more inclined to adopting a bipedal stance.

A Tale in a Tail!  Researchers Explain the Presence of Bipedalism within the Dinosauria

 

Gorgosaurus libratus illustrated.

A tale in the tail – the caudofemoralis provides propulsion leading to an evolutionary bias towards a bipedal stance.

Picture Credit: Everything Dinosaur

17 03, 2017

Primitive Neornithischian Dinosaurs and Seed Dispersal

By | March 17th, 2017|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Plant-Eating Dinosaurs Probably Played an Important Role in Seed Dispersal

Time to catch up on our reading and first on the list of papers is this fascinating insight into the relationship between plant-eating dinosaurs and seed dispersal.  An international team of scientists from Portugal, Spain and Argentina have described a new species of primitive, bird-hipped dinosaur and an assessment of the body cavity led to the discovery of the dinosaur’s last meal.  Permineralised seeds, most of which having been identified as coming from cycads (Cycadales), suggest that herbivorous dinosaurs played an important role in seed dispersal, just as many plant-eating mammals do today.

The New Argentinian Dinosaur Isaberrysaura mollensis is Related to Kulindadromeus from Siberia

A scale model of the feathered dinosaur Kulindadromeus.

A 1:1 scale model of Kulindadromeus, closely related to Isaberrysaura.

Picture Credit: T. Hubin/RBINS

The researchers which include lead author, Leonardo Salgado (CONICET – Universidad Nacional de Río Negro), conducted a phylogenetic analysis and assigned this new dinosaur species to the basal Ornithopoda, suggesting that it is closely related to Kulindadromeus (K. zabaikalicus), fossils of which are known from geologically younger strata found in Siberia.  However, this new dinosaur, named Isaberrysaura was much larger, with an estimated body length of approximately six metres.

The Feeding Habits of Herbivorous Dinosaurs

Despite some two-thirds of all the dinosaurs described to date being plant-eaters, there is little direct evidence of the feeding habits of herbivorous dinosaurs that matches the stomach contents preserved within a carcase.  Most unaltered gut content that has been found is associated with much later dinosaurs -hadrosaurids and ornithopods.  This is the first time that gut contents have been identified in association with the remains of a basal neornithischian.

The specimen, representing a single individual, consists of an almost complete skull, vertebrae, part of the left shoulder blade (scapula), along with ribs and elements from the pelvic girdle.  It was excavated from the Los Molles Formation (Neuquén Basin, Argentina), from sediments that suggest a coastal-delta environment, the presence of the zone ammonite Sonninia altecostata in the same fossil bed, indicate that Isaberrysaura lived some 170 million years ago (Early Bajocian faunal stage of the Middle Jurassic).  These are the first dinosaur remains found in this geological unit and the one of the oldest dinosaurs known from the Neuquén Basin.  In addition, this is the first neornithischian dinosaur known from the Jurassic of South America.  The skull and the teeth show some affinity with basal stegosaurids which suggests that both the Thyreophora and neornithischian dinosaurs shared a lot of similar features (potential evidence of convergent evolution amongst plant-eating dinosaurs).

Isaberrysaura mollensis – Views of the Skull and Teeth

Isaberrysaura mollensis - views of the skull and teeth.

The skull in (a) dorsal and left lateral view (c) with corresponding line drawings (b and d).  Premaxillary tooth (e) and maxillary teeth (e and f).

Picture Credit: Scientific Reports

 Why Isaberrysaura?

This month, we have once again been celebrating International Women’s Day (March 8th), it is pleasing to note that the female form of “saurus” has been chosen when it came to naming this new dinosaur, as the genus has been erected to honour Isabel Valdivia Berry, who reported the finding of the holotype material.  In the body cavity, the researchers were able to identify a mass of permineralised seeds.  These were identified as belonging mostly to the Cycadales group of plants.  These tough seeds would have passed through the dinosaur’s gut and would have been deposited in the dung.  This fossil discovery suggests a possible and unexpected role of bird-hipped dinosaurs, that of Jurassic seed-dispersal agents.

An Analysis of the Gut Contents of Isaberrysaura 

The gut contents of Isaberrysaura mollensis.

Permineralised seeds identified in the gut cavity of Isaberrysaura mollensis.

The photograph above shows images of the body cavity showing evidence of the seed fossils.

Some of the fossils show that their fleshy seed-coats are still intact (sc = sarcotesta), this indicates that these seeds were swallowed whole with little or no chewing action in the mouth.

The scientific paper: “A New Primitive Neornithischian Dinosaur from the Jurassic of Patagonia with Gut Contents”, published in the journal “Scientific Reports”

15 03, 2017

Not All Mesozoic Crocodiles Were Giants

By | March 15th, 2017|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Knoetschkesuchus – Living on an Island

Last month, scientists published in the on line academic journal “PLOS ONE” a paper that provided details of the discovery of a new species of Late Jurassic terrestrial crocodile, but this animal was no ground-shaking giant, like most of its kind (atoposaurids), it probably had a maximum length of under a metre and it would have weighed a couple of kilogrammes or so.

Lead author of the research paper, Daniela Schwarz (Leibniz Institute for Evolutionary and Biodiversity Research, Germany), in collaboration with colleagues, re-examined fossils including skull material (an adult and a juvenile specimen), that had previously been assigned to the atoposaurid Theriosuchus – a genus of crocodile-like reptile that is known from a large number of fossils dating from the Late Jurassic and into the Early Cretaceous from places as far apart as Thailand and southern England.  However, when the beautifully preserved fossils were studied using CT scans and three-dimensional images of the fossil material created, a number of autapomorphies were identified to allow the erection of a new genus.

A View of the Larger Specimen of Knoetschkesuchus langenbergensis

Knoetschkesuchus langenbergensis fossil material (larger specimen).

Knoetschkesuchus langenbergensis fossil material.

Picture Credit: PLOS ONE

The little crocodile has been named Knoetschkesuchus langenbergensis, the fossils come from the famous Langenberg Quarry, located near the town of Goslar, Lower Saxony, northern Germany.  The limestones and marls that form the quarry site, were laid down in shallow inlets associated with an island archipelago.  The Knoetschkesuchus material comes from Bed 83, the same location as the fossils of the dwarf Sauropod Europasaurus (E. holgeri).

Lots of Terrestrial Crocodiles in the Mesozoic

Knoetschkesuchus langenbergensis fossil material has been dated to the Upper Kimmeridgian stage of the Jurassic, approximately 154 million years ago, like most members of the Atoposauridae it had large eyes and it may have been a fast runner.  The researchers conclude that the Langenberg Quarry fossils represent a new species because of unique features of the skull, such as openings in the jaw bone and in front of the eye, as well as the shape and placement of the animal’s tiny teeth.  The teeth are heterodont in nature (different shapes), at the tip of the snout they are pointy and needle-like, very typical of a small crocodilian, but towards the back of the jaws they are broader and more rounded, particularly in the lower jaw.  It has been suggested that these teeth were adapted for crushing hard-shelled prey, such as snails, which are known from abundant gastropod fossils associated with Bed 83.

Line Drawings Showing Various Views of Both the Adult and Juvenile Skull Specimens

Knoetschkesuchus skull illustrations

Knoetschkesuchus skull drawings.

Picture Credit: PLOS ONE with additional annotation by Everything Dinosaur

Note

Elements of the adult skull fossil have been drawn based on scaled-up material from the juvenile specimen.

Dr Schwarz commented:

“The study describes a new diminutive crocodile Knoetschkesuchus langenbergensis that lived around 154 Million years ago in north-western Germany.  Knoetschkesuchus belongs to the evolutionary lineage that leads to modern crocodiles and preserves for the first time in this group two skulls in 3-D, allowing us detailed anatomical studies via micro-CT images.  Our research is part of the Europasaurus-Project which studies the remains of a unique Jurassic island ecosystem in northern Germany.”

A Unique Island Ecosystem

The Langenberg Quarry preserves the remains of a unique Late Jurassic European ecosystem.  The islands were relatively small and this led to a divergence between residents of these islands and their ancestors which lived on the larger landmasses to the east.  For example, in response to limited food resources and space, the Sauropod Europasaurus became a dwarf form.  The atoposaurid crocodiles probably filled a number of ecological niches within the food chain, including that of arboreal predators.  These distant ancestors of today’s crocodiles were in turn preyed upon by a variety of Theropod dinosaurs, the majority of which are only known from fragmentary teeth.  What is quite remarkable, is the diversity of the Theropod teeth found in Upper Jurassic deposits of northern Germany.  Studies have suggested that representatives of the Tyrannosauroidea, as well as Allosauroidea, Megalosauroidea and probably Ceratosauria roamed this part of the world some 155 to 150 million years ago.

The genus name (Knoetschkesuchus) is a combination of the family name of Nils Knötschke, and suchus (from the Greek meaning crocodile).  The genus name honours of Nils Knötschke (Dinosaurier-Freilichtmuseum Münchehagen), who collected, prepared, and curated several important fossil specimens from the Langenberg Quarry.

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