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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.

14 11, 2018

Fossil Bird from Late Cretaceous Utah – Deepens a Mystery

By | November 14th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Mirarce eatoni – Deepens the Mystery Over Late Cretaceous Avian Extinctions

All living birds from Albatrosses to Zebra finches belong to one group of avians – the Neornithes.  Our feathered friends share a number of key anatomical traits that defines them as a group from the smallest such as the Bee Hummingbird to the largest living bird, the Ostrich.  However, back in the Cretaceous, things were very different.  There were several different taxa of birds including the very diverse and highly successful Enantiornithines that shared the skies with early members of the Neornithines, but only the ancestors of today’s extant birds survived the end-Cretaceous extinction event and that’s a puzzle for palaeontologists.

The puzzle has just become a little more complex with the publication of a scientific paper in the on-line, open access journal “PeerJ”.  This paper describes the fossilised remains of an Enantiornithine that lived around 75 million years ago, in Utah (USA).  This prehistoric bird, about the size of a Raven, has been named Mirarce eatoni and its fossils show that it was probably a match for most modern birds in terms of its aerial abilities.

Perched on the Horns of a Utahceratops (Mirarce eatoni)

Mirarce eatoni - life reconstruction.

An illustration of the Late Cretaceous enantiornithine Mirarce eatoni.

Picture Credit: Brian Engh

This leads to one very intriguing question, if Enantiornithines like Mirarce were so advanced, then why after the Cretaceous-Palaeogene mass extinction event did only one group of birds survive?

A Complete Anatomical Description

The fossil material consists of several neck bones (cervical vertebrae), back bones (dorsal vertebrae), the fused caudal vertebrae making up the pygostyle, elements from the limbs, parts of the hips, a partial scapula, coracoid, the furcula (wishbone) and several other fragmentary elements including the radius and ulna.  This represents a veritable treasure trove of North American Enantiornithine fossils for palaeontologists to study, most North American members of this taxon are known from very scrappy fossil remains, mostly consisting of isolated fused leg bones and toes.  All in all, about 30% of the total skeleton is known and crucially, unlike most of the more complete Enantiornithine specimens from the Lower Cretaceous deposits of China, this specimen, is preserved in three-dimensions, it has not been crushed as flat as a pancake.  The excellent state of preservation and the number of fossil bones has permitted the researchers to undertake a complete anatomical description.

A Skeletal Reconstruction of the Newly Described North American Enantiornithine Mirarce eatoni

Mirarce eatoni skeletal reconstruction.

A skeletal reconstruction of the Enantiornithine Mirarce eatoni from Late Cretaceous Utah.  The bones shaded white represent known fossil material.  Note, cranial material is not known.

Picture Credit: Scott Hartman

The “Kaiparowits Avisaurid”

The specimen was originally discovered back in 1992, by University of California, Berkeley palaeontologist Howard Hutchinson, whilst he was exploring Kaiparowits Formation deposits for evidence of turtles.  It was quickly identified as an Enantiornithine and ascribed to the Avisauridae family, a family of prehistoric birds known from South America, North America, parts of Europe, Siberia and the Middle East (Lebanon).  The partial skeleton (UCMP 139500), was nicknamed the “Kaiparowits avisaurid”.   Although, its significance was noted, after all, the fossils represent the most complete example of an Enantiornithine ever found in North America, it remained undescribed.  All that changed when PhD student Jessie Atterholt (University of California, Berkeley), was given the opportunity to provide a formal scientific description.

Research Suggests that Mirarce eatoni was a Strong Flier and Well-Adapted to Life in the Late Cretaceous

Mirarce eatoni - life reconstruction.

A close-up view of the newly described Late Cretaceous bird Mirarce eatoni (colouration and plumage speculative).

Picture Credit: Brian Engh

A Strong and Capable Flier

In collaboration with her colleague Howard Hutchinson and with the support of Jingmai O’Connor, from the Chinese Academy of Sciences and an authority on Cretaceous fossil birds, a complete analysis of the fossil bones was undertaken.  This study revealed that M. eatoni possessed several of the same physical adaptations for highly refined powered flight that modern birds (Neornithines) have.

Fossils of Enantiornithines from the Lower Cretaceous of China, birds such as Confuciusornis sanctus show a mix of basal and more advanced anatomical traits.  For example, the breast bone (sternum), of C. sanctus, is relatively small.  Modern birds have a deeply keeled sternum, this allows the attachment of large muscles to aid powered flight.  The wishbone (furcula) of Confuciusornis and most other Early Cretaceous Enantiornithines, is little more than a curved bar.  However, the furcula of M. eatoni is shaped much more like the “V-shaped” wishbones of modern birds.  The furcula of Mirarce would have been able to flex and to store energy released during the flapping of the wings.

Commenting on the significance of these anatomical characteristics, Atterholt stated:

“We know that birds in the early Cretaceous, about 115 to 130 million years ago, were capable of flight but probably not as well adapted for it as modern birds.  What this new fossil shows is that Enantiornithines, though totally separate from modern birds, evolved some of the same adaptations for highly refined, advanced flight styles.”

The Furcula (Wishbone) of Mirarce eatoni

The furcula of Mirarce eatoni.

Two views of the wishbone (furcula) of Mirarce eatoni (A) dorsal and (B) ventral with line drawings.  Scale bar = 1 cm.

Picture Credit: PeerJ

Quill Knobs?

A close examination of the right ulna (lower arm bone), revealed evidence of two roughened patches preserved on the shaft of the bone.  These rough patches were interpreted as being attachment sites for quill knobs, that anchor the wing feathers to the skeleton and to help strengthen the wings for use in active, prolonged, powered flight.  Quill knobs are found in living birds.  This is the first time that such a feature has been seen in an Enantiornithine and indicates that Mirarce was, very probably, a strong flier.

Potential Quill Knobs Identified in an Enantiornithine (M. eatoni)

Quill knobs on an Enantiornithine.

Roughed structures on the ulna of Mirarce compared to the quill knobs found on the ulna of a Pelican.

Picture Credit: PeerJ

If these structures are quill knobs, then this suggests that this anatomical trait evolved in parallel with members of the Dinosauria (dromaeosaurids and other maniraptorans along with the ornithomimids) and in parallel with a number of types of prehistoric bird.

How Did Mirarce Get Its Name?

The genus name reflects that fantastic state of preservation of the fossil material (Latin “mirus” for wonderful) and after Arce, the winged messenger of the Titans in Greek mythology.  The trivial name honours Dr Jeffrey Eaton, in recognition of his work studying the vertebrates of the Kaiparowits Formation.  A spokesperson from Everything Dinosaur commented that this prehistoric bird’s name was pronounced “mere-ark-ee ee-tow-eye”.

But Why Did These Advanced Enantiornithines Die Out?

If Late Cretaceous Enantiornithines were just as advanced as modern birds, then, why did they die out with the non-avian dinosaurs while the ancestors of modern birds survived the extinction event?

Atterholt, who has moved onto a position of Assistant Professor and human anatomy instructor at the Western University of Health Sciences in Pomona (California), added:

“This particular bird is about 75 million years old, about 10 million years before the die-off.  One of the really interesting and mysterious things about Enantiornithines is that we find them throughout the Cretaceous, for roughly 100 million years of existence and they were very successful.  We find their fossils on every continent, all over the world, and their fossils are very, very common, in a lot of areas more common than the group that led to modern birds.  Yet modern birds survived the extinction while Enantiornithines go extinct.”

Forest Dwellers Versus Seed Eaters

A number of ideas have been put forward to help explain why some types of birds survived the end-Cretaceous mass extinction event whilst others did not.  For example, one hypothesis proposes that Enantiornithines were forest dwellers and when the asteroid strike/volcanism resulted in a dramatic loss of woodland habitats, these types of birds suffered more than other birds that lived in different environments.

The absence of cranial material prevents the researchers from investigating what Mirarce might have eaten.  Most known members of the Enantiornithes had teeth in their beaks and Mirarce supports the idea that these types of birds gradually got larger over time, but what this bird ate remains a mystery.  If it had been a predator of small vertebrates and insects, any major disruption to the food chain could have led to extinction.  However, a paper published in 2016 proposed that birds with toothless beaks such as the early Neornithines could have survived the extinction event by eating seeds that persisted in the soil.

To read more about this paper: Seed Eating May Have Helped the Birds Survive

The scientific paper: “The Most Complete Enantiornithine from North America and a Phylogenetic Analysis of the Avisauridae” by Jessie Atterholt, J. Howard Hutchinson and Jingmai K. O’Connor published in PeerJ.

5 11, 2018

Super Efficient Lungs Powered Dinosaur Success

By | November 5th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

Bird-like Lungs Could Have Helped Dinosaurs to Dominate

There has been a great deal of debate regarding the rise of the Dinosauria.  How and when did these relatively unassuming members of the Dinosauria, which only made up a small proportion of terrestrial biota during the Middle Triassic, rise to dominance, out-competing a host of other reptilian groups?  The respiratory system of dinosaurs could provide a clue.  In a new study publised in the open access journal of the Royal Society (Royal Society Open Science), a team of researchers postulate that the lung-air sac system could have helped dinosaurs thrive in Earth’s oxygen-depleted atmosphere.

Did a Super-efficient Pumonary System Help the Dinosaurs to Thrive?

Dinosaurs probably had a super-efficient respiratory system.

New research suggests super-efficient dinosaur lungs assisted the rise of the Dinosauria.

Picture Credit: Chinese Academy of Sciences

Studying the Breathing Systems of Modern Birds and Alligators

Birds have a super-efficient respiratory system that is unique amongst the vertebrates.  However, palaeontologists remain uncertain as to when the avian-style lung evolved.  Did it evolve in dinosaurian ancestors or is it restricted to birds?  After all, if you are going to fly, then you need a very efficient and powerful set of lungs to get enough oxygen to your flight muscles.

This area of anatomy has attracted a great deal of debate.  Recently, Everything Dinosaur reported on a study conducted on a specimen of Archaeorhynchus spathula, a primitive bird (basal member of the Ornithuromorpha), from the Lower Cretaceous of China, that may show preservation of an advanced avian lung.  To read more about this research: Breathing Life into the Bird Lungs Debate

The scientists, including researchers from the University of Manchester, compared dinosaur lungs to those of living crocodilians and the lungs of extant birds.  Lead researcher, PhD student Robert Brocklehurst (School of Earth and Environmental Sciences, Manchester University), stated:

“The respiratory system of non-avian dinosaurs has been the topic of considerable study over the years, both in an attempt to shed light on the biology of now extinct members of the dinosaur family, and in order to understand the origins and evolution of modern birds and reptiles.”

Low Oxygen Levels in the Triassic and Early Jurassic

Today, our atmosphere contains approximately 21 percent oxygen, however, things have not always been like that.  During the Middle Triassic, through to the Early Jurassic, a time that saw the evolution and the radiation of the Dinosauria, the atmospheric oxygen percentage of our planet fell to around 15-17%.   With less oxygen in the air, a group of vertebrates with more efficient lungs would have had a definite evolutionary advantage over other terrestrial animals.

During the Triassic A Wide Variety of Terrestrial Reptilian Vertebrates Co-existed

The flora and fauna of the Late Triassic.

Dinosaurs, Aetosaurs, Phytosaurs and and Rauisuchians co-existed in the Triassic, but did super-efficient lungs help the Dinosauria to become dominant.

Picture Credit: Victor Leshyk

To investigate the different kinds of respiratory systems the team used Computerised Tomography (CT) scans to look at the lung cavities of four modern crocodilians and twenty-nine modern birds, including the largest living bird today, the ostrich and compared their structure with those of sixteen different dinosaur species.  The detailed scans revealed that all the dinosaurs had vertebrae more similar in shape to those of birds than those of crocodilians.  In addition, the scientists discovered that the dinosaur vertebrae jutted into the lung cavity, the same as found in living birds.

Robert explained:

“We thought some of the dinosaurs would have lungs more like birds, and others would be similar to reptiles, but this wasn’t the case at all.  Every dinosaur sample we scanned just looked like the birds we scanned.”

Dissection Used in this Study

As well as using CT scans, the team removed the lungs of an alligator and an ostrich, and found the skeletal support structures surrounding the lungs were very different in each animal.  The alligator’s lung cavity was smooth and allowed the lungs and other internal organs to glide as they move to pump air in and out while the animal swims.  However, the ostrich lung cavity was found to be furrowed, similar to the anatomical condition found in the dinosaurs.

The scientists concluded that having more efficient bird-like lungs permitted the dinosaurs to adapt and thrive in an oxygen depleted environment, whereas other groups including the the Crurotarsi clade of Archosaurs that gave rise to modern crocodiles, struggled.

Commenting on the research, co-author Professor Bill Sellers (Manchester University) added:

“If even the very first dinosaurs to evolve had bird-like lungs, this goes some way to explaining why dinosaurs became the dominant animal species of their time.  Other animal groups simply may not have had lungs as well suited to extracting oxygen from the air.  That simple evolutionary difference may have let dinosaurs rule world.”

The scientists concluded that respiratory and pulmonary modifications would have provided dinosaurs with more efficient means of oxygen uptake relative to other vertebrates during the environmentally hypoxic conditions which pervaded much of the early part of the Mesozoic.  This anatomical advantage enjoyed by the Dinosauria could thus potentially have contributed to their radiation and dominance over terrestrial ecosystems, which was to last for around 150 million years.

The Lungs of Dinosaurs Helped to Power Their Evolutionary Success

The sophisticated respiratory system of Ingentia prima.

The air sacs of Ingentia prima (green) the lungs shown in brown.  This large, Early Jurassic Sauropod had a super-efficient respiratory system.

Picture Credit: Jorge A. González

Everything Dinosaur acknowledges the assistance of a press release from Manchester University in the complilation of this article.

The scientific paper: “Vertebral Morphometrics and Lung Structure in Non-avian Dinosaurs” by Robert J. Brocklehurst, Emma R. Schachner and William I. Sellers published in Royal Society Open Science.

3 11, 2018

Elaborate Plumage in Confuciusornis

By | November 3rd, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Patterns on the Feathers of Confuciusornis as Complex as Modern Birds

A team of international scientists, including researchers from the China University of Geosciences (Beijing), the University of Ghent (Belgium) and the University of Texas at Austin (United States), have discovered that the patterns on the feathers of an Early Cretaceous bird may have been very similar to and as complex as the patterns seen on the feathers of extant Aves.  Writing in the academic, on-line journal “PeerJ”, the researchers conclude that the patterning of Confuciusornis feathers probably performed similar functions to the patterning on modern bird’s feathery coats, that is, they provided camouflage and also played a role in display.

Confuciusornis Integumentary Covering – Elaborate Plumage

Study suggests Confuciusornis had elaborate plumage.

Reconstruction of the plumage of Confuciusornis (specimen number CUGB P140).

Picture Credit: Li et al (PeerJ)

Complex Patterning Detected by Sophisticated Chemical Analysis

The specimen studied consists of a slab and counter slab of a single, individual bird from Early Cretaceous deposits in Fengning County, Hebei Province (north-central China).  The fossils are from the vertebrate collection of the China University of Geosciences and represent an example of Confuciusornis sanctus.  The research team identified exceptional feather preservation but poor preservation of the bones, the unusual state of preservation permitted the scientists to identify melanin signals in the fossilised feathers indicating a complex patterning of spots on the wings, throat and on the tuft of feathers at the back of the head forming a small crest.  The shape of the structures that form these patterns in conjunction with chemical analysis confirmed the diagnosis of the pigment melanin.  However, specific colouration associated with the patterns could not be discerned.

The Slab and Counter Slab or a C. sanctus Specimen Reveals Complex Patterning on the Plumage

Evidence of Confuciusornis plumage.

Evidence of plumage diversity in the Confuciusornithidae from the new specimen (CUGB P1401).

Picture Credit: Li et al (PeerJ)

The photograph (above) shows various views of the main slab of the fossil specimen showing details of the plumage.  The dots in (A) indicate places that were subjected to sampling, whereas B and C reveal the crest located on the back of the head.  Parts D and E show elements of the integumentary covering in close detail.

Using a range of analytical techniques including scanning electron microscopy and ion mass spectrometry (ToF-SIMS) the researchers concluded that the elaborate spotting on this specimen exceeds that found in exceptionally-preserved troodontids and compsognathids and rivals that in modern birds, suggesting that plumage patterns evolved greater complexity through avian evolution.

The exact age of the strata is uncertain, although it is believed that the deposits from Fengning County are approximately equivalent in age with the Dawangzhangzi Member of the Yixian Formation, around 122-123 million years old (Aptian faunal stage of the Early Cretaceous).  The data from this study suggests that Confuciusornis had more complex patterning than the patterning identified in Achiornis or in the stripes of the compsognathid Sinosauropteryx.  The research team conclude that this specimen of a primitive bird provides evidence to support the idea that complex patterning of feathers evolved at a relatively early stage in avian evolution.

The Link to Barn Owls

Integumentary patterns and colours play a variety of roles in living birds.  Such patterning in fossil specimens probably performed the same sort of functions and in addition, they can help to inform on the habitat in which the extinct creature lived.  In some modern bird groups, barn owls for example (Strigiformes), it has been observed that the size and placement of the spots on the feathers play a role in mate selection.  Male barn owls tend to prefer females with larger spots.  The patterning identified on this C. sanctus specimen leads to the intriguing idea that for confuciusornithids, just like barn owls, the location and the size of the spots on the plumage played a role in choosing a mate.

The scientific paper: “Elaborate Plumage Patterning in a Cretaceous Bird” by Quango Li, Julia A. Clarke, Ke-Qin Gao, Jennifer A. Peteya and Matthew D. Shawkey published in PeerJ.

27 10, 2018

Pachycephalosaurus – Was It Carnivorous?

By | October 27th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Theropod-like Front Teeth Identified in a Pachycephalosaur

Pachycephalosaurus, that dome-headed dinosaur that lived alongside such famous prehistoric animals as T. rex and Triceratops, in the Late Cretaceous of Montana, has always been a bit-player when it comes to depicting life in the very last couple of million years before the extinction of the non-avian dinosaurs.  Its more illustrious contemporaries tend to hog the limelight somewhat.  However, the scientific description of a nearly complete skull and jaws of what has been identified as a juvenile Pachycephalosaurus, might just have revealed a surprising side to this peaceful plant-eater.  The teeth in the front of jaws are triangular and pointed, reminiscent of the dentition of a meat-eating dinosaur.  Could palaeontologists have got Pachycephalosaurus wrong?

A Reconstruction of the Juvenile Pachycephalosaurus Skull and Jaws

Reconstruction of a Juvenile Pachycephalosaurus skull.

A reconstruction of the fossil skull of the juvenile Pachycephalosaurus that has Theropod-like teeth in the front of the jaws.

Picture Credit: Brian Boyle (Royal Ontario Museum)

Front Portion of the Jaws Suggests Omnivory in Certain Pachycephalosaurs

In a presentation made at the annual meeting of the Society of Vertebrate Palaeontology held in Albuquerque, New Mexico, Mark Goodwin (University of California Museum of Palaeontology) and David Evans (Royal Ontario Museum), described a near complete juvenile Pachycephalosaur skull from eastern Montana.  The back of the jaws contained the broad, leaf-shaped teeth which seem well suited to herbivory.  It had been assumed that the teeth in the front of the jaws (premaxilla and the anterior portion of the dentary, immediately behind the predentary), were the same shape.  However, until this fossil specimen was found, no record of the front teeth of these dinosaurs existed.  Palaeontologists may have to re-think their views on the diet of this member of the Hell Creek Formation biota.  The sharp, blade-like triangular teeth located at the front of the mouth seem adapted to ripping and tearing flesh.

The Teeth at the Front of the Jaws are Typical of a Meat-eating Theropod Dinosaur

Pachycephalosaurus Theropod-like teeth.

A close-up view of the teeth in the premaxilla (upper jaw) and the anterior portion of the dentary (lower jaw). Triangular Theropod-like teeth have been identified in a juvenile Pachycephalosaurus.

Picture Credit: Brian Boyle (Royal Ontario Museum) with additional annotation by Everything Dinosaur

Confusing Pachycephalosaurs

Pachycephalosaurus is the largest member of the Pachycephalosauridae family to have been scientifically described and notwithstanding a cameo appearance of a jail-breaking Stygimoloch in the recent “Jurassic World – Fallen Kingdom” movie, perhaps the most famous.  However, not a great deal is known about Pachycephalosaurus and other bone-headed dinosaurs.  Fossil remains tend to be very fragmentary and most species have been named from quite scrappy remains and then you have those amazing skulls to consider.

The CollectA Pachycephalosaurus Dinosaur Model

CollectA Pachycephalosaurus model.

A lithe Pachycephalosaurus dinosaur model.  Pachycephalosaurus (P. wyomingensis) is the largest known member of the Pachycephalosauridae with an estimated body length of 4.6 metres.

Picture Credit: Everything Dinosaur

Several species have been named based on the shape and cranial ornamentation associated with those thickened skulls.  The thick bone may resist erosion and provide palaeontologists with some fossil bone to study, but it has been suggested that the skulls of these dinosaurs changed dramatically as the animal grew.  So much so in fact, that a number of academics, including Mark Goodwin, have published scientific papers that cast doubt on the validity of many Pachycephalosaur species.  For example, palaeontologists such as Goodwin have put forward evidence to suggest that both Dracorex and Stygimoloch are not distinctive species, the fossils ascribed to these two genera could represent juvenile Pachycephalosaurus specimens.

It seems, just like many other types of Late Cretaceous Ornithischian dinosaur, the Pachycephalosaurs underwent extreme changes to the shape of their heads as they grew up.  Such changes in cranial morphology have resulted in the establishment of several species that may actually just represent examples of the same species but at different growth stages.

Some Palaeontologists Suggest that Radical Changes in Skull Shape and Ornamentation Do Not Indicate Different Species but Different Growth Stages

Different skull shapes and ornamentation linked to different growth stages.

It has been proposed that the cranial ornamentation and skull shape of Pachycephalosaurs changed as these animals grew and matured. This can cause confusion when trying to identify species.

Picture Credit: Kari Scannella with additional annotation by Everything Dinosaur

To complicate matters, Pachycephalosaur fossil material covers a period of approximately 2 million years.  Over this timescale, these animals evolved and their skull morphology changed, thus, further blurring the lines between different species and fossils of the same species but at different levels of maturation.

Confirming the Likely Diet of Pachycephalosaurus

It would be difficult to confirm that Pachycephalosaurus also ate other animals as well as plants, but not impossible.  Only one jaw fossil with the front teeth in situ has been found, so scientists don’t know whether the diets of these dinosaurs changed as they grew.  Perhaps, young Pachycephalosaurs were omnivorous, whilst when fully grown, adults tended to consume plants rather than other animals.  The rib cages of those genera which have a more complete fossil record, suggest that these bipeds had large guts, this would indicate a digestive system adapted to processing vegetation.  Professor Philip Currie (University of Alberta), who also attended the Society of Vertebrate Palaeontology meeting, has proposed that studying carbon isotopes preserved in the tooth enamel might provide further evidence relating to diet.  In addition, the many hundreds of examples of isolated, broken teeth from the Hell Creek Formation could be re-examined and checked for any potential affinities with the Pachycephalosauridae.  Feeding traces from fossil bone could also yield more data in support of the idea that bone-headed dinosaurs ate meat.

A Reconstruction of the Skull of an Adult Pachycephalosaurus

A replica skull of Pachycephalosaurus wyomingensis.

Pachycephalosaurus wyomingensis replica skull.

Picture Credit: Everything Dinosaur

A spokesperson from Everything Dinosaur commented:

“It is likely that there are many more examples of Pachycephalosaurs to be found in Upper Cretaceous rocks, hopefully, if more fossil material can be discovered, then palaeontologists will be able to piece together a more complete phylogeny of these strange dinosaurs.  Furthermore, if more examples of their dentition [teeth] come to light, then we might be able to gain a better understanding of their diets. “

21 10, 2018

Flea Bites and Dermal Infections in Glyptodonts

By | October 21st, 2018|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|2 Comments

Fleas on Glyptodonts

A new study examining one of the more bizarre types of megafauna from prehistoric South America has revealed that glyptodonts and their relatives suffered from fleas and dermal infections.  It seems that the hard, bony armour of some of these car-sized giants was no defence against flea bites.  Brazilian-based scientists writing in the open access, on-line journal “PLOS One”, have studied hundreds of pieces of glyptodont armour and discovered evidence of infections caused by fleas.

Such armour might have deterred a sabre-toothed cat from attacking, but the osteoderms and armoured tails were no defence against parasites.

A Skeleton of the Giant Glyptodont Panochthus spp.

Fossil glyptodont Panochthus.

A glyptodont fossil (Panochthus frenzelianus).  Researchers studied the tiles of bone (osteoderms) that formed the protective bony exoskeletons of extinct types of armadillo and determined that these armoured giants suffered from parasites and skin infections.

Picture Credit: R. Somma/Wikimedia Commons

Extinct Members of the Order Cingulata Studied

The scientists from Universidade Federal Rural do Semi-Árido, Mossoró (Brazil), studied the osteoderms that make up the exoskeleton of two extinct genera of glyptodonts Panochthus (pictured above) and Glyptotherium.  In addition, the research team examined the fossilised armour of another extinct armadillo-like creature Pachyarmatherium.  All these mammals belong to the Order Cingulata (armadillos and their relatives).  Damaged osteoderms were noted in all three genera and attributed to attacks by fleas and infections.  The scientists were able to identify the flea bites as coming from one particular genus  – Tunga.  The Tunga flea, sometimes referred to as the “jigger flea”, is native to South and Central America and is known to parasitise a number of large mammals including humans.  The bites cause well-defined circular lesions and perforations.  Such patterning was identified in a number of fossilised pieces of dermal armour.

Flea bites permitted secondary damage to be caused by the invasion of pathogenic microorganisms such as bacteria and fungi.

The External Surface of Osteoderms from the Glyptodont Glyptotherium Showing Pitting and Damage

Cingulata osteoderm parasite infection.

Osteoderms of the Brazilian glyptodont Glyptotherium showing damage from flea bites.

Picture Credit: PLOS One

The picture (above) shows severe pitting (black arrows) in (A) and three other osteoderms attributed to Glyptotherium which show stages of damage from (B), slight, through to (D) advanced pitting and the response to the damage by the deposition of more bone (calcium deposition).  The scale bar in A = 3 cm, whereas, the scale bar in B-D is 4 cm.

A Life Reconstruction of the Brazilian Glyptodont Glyptotherium

Glyptotherium life reconstruction.

A life reconstruction of the giant South American glyptodont Glyptotherium.

Picture Credit: Larjard/Wikimedia Commons

The bone alteration and re-growth identified in this study represent the first record of flea attack and pitting in two genera of large glyptodonts Panochthus and Glyptotherium and in a non-glyptodontid, large cingulate (Pachyarmatherium), from the Quaternary of the Brazilian Intertropical Region.  These newly identified flea bite occurrences and subsequent infections widen the geographic distribution of those diseases during the Cenozoic and provide more evidence for the co-evolution of parasites such as the Tunga flea and South American megafauna.

The scientific paper: “Ectoparasitism and Infections in the Exoskeleton of Large Fossil Cingulates” by Fábio Cunha Guimarães de Lima, Kleberson de Oliveira Porpino published in PLOS One

19 10, 2018

Feeding Traces on the Frill of a Young Centrosaurus

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

Bite Marks Found on the Frill of a Young Centrosaurus

The movies and television documentaries featuring dinosaurs are stuffed full of them, but the fossil record tells a different story.  What are we referring to?  Dinosaurs hunting, attacking and fighting other dinosaurs.  Rarely has a programme or film been produced about the Dinosauria that does not feature some gory scenes of a bloody battle or a fearsome Theropod feasting on some poor, unfortunate plant-eating victim.  However, although such interactions obviously took place, the fossil record demonstrating such behaviour is extremely sparse.  A new paper, published in the open access journal “PeerJ”, reports on the discovery of bite marks preserved on the frill of a young Centrosaurus.

This raises two intriguing questions:

  • Which meat-eating dinosaur made the bite marks?
  • Is this evidence of predation or scavenging a carcass?

Dinosaurs Fighting – A Tyrannosaur Attacks a Horned Dinosaur (Styracosaurus)

Daspletosaurus fighting a horned dinosaur.

Tyrannosaur fighting a horned dinosaur.

Picture Credit: John Gurche

Bite Marks – Tell-Tale Signs of Predator/Prey Interaction

Bite marks on fossil bones can provide valuable information about interactions between carnivorous dinosaurs and the animals that they attacked.  It is not always possible to distinguish whether the trace fossils represent wounds inflicted on an animal during a fight, or whether these marks represent post-mortem feeding, such as consumption of the victim.  If there are signs of healing and bone growth, palaeontologists can be confident that the bite marks in that instance represent a lucky escape for the intended victim.  The key thing to note, is that the more data about bite marks that can be collected, the better the dataset that palaeontologists have to compare potential bite mark injuries against.

Part of the Skull of a Juvenile Centrosaurus With Tooth-marks

Ironically, quite a large proportion of the tooth-mark fossils associated with dinosaurs come from those deposits that are associated with the remains of large-bodied tyrannosaurids.  In this newly published paper, the scientists from Queen Mary University London and the Royal Tyrrell Museum (Alberta, Canada), report on the discovery of a portion of the skull from a juvenile horned dinosaur.  The bone, a fragment of the squamosal, which makes up part of the frill, was found on the surface of a dinosaur bonebed in the Dinosaur Provincial Park Formation.  The fossil is approximately 76.3 to 75.6 million years old and has been assigned to the horned dinosaur species Centrosaurus apertus.

Views of the Fragment of the Squamosal Bone (Centrosaurus apertus) and Line Drawings

Identifying potential bite marks in a bone from a juvenile Centosaurus.

The two sides of the partial squamosal bone from a juvenile Centrosaurus showing signs of damage/wear/bite marks. Actual fossil (A and B), interpretive line drawings (A1 and B1).

Picture Credit: PeerJ with additional annotation by Everything Dinosaur

Key

BM = Probable bite marks

? = Possible bite marks

Analysis of the fossil found numerous marks and gouges on both sides of the fossil bone.  Some of these marks could have resulted from damage due to transportation prior to burial.  Other marks could reflect effects caused by chemical erosion or the presence of vascular grooves.  However, the scientists were able to propose that at least some of the marks were due to teeth coming into contact with the bone.

The Position of the Partial Squamosal on the Skull of a Juvenile Centrosaurus and an Adult Skull Shown for Comparison

Juvenile (A) and adult (B) Centrosaurus skulls.

A comparison of Centrosaurus skulls (C. apertus) Juvenile (A) and adult (B).  The squamosal bone that makes up part of the frill is shaded grey, whilst the portion of bone in the study is shaded dark grey.

Picture Credit: PeerJ

Although it is difficult to assess the size of the horned dinosaur based on such a small fragment of bone, the scientists suggest that based on comparisons with squamosal bones from adults, the juvenile Centrosaurus was perhaps about a third the size of a fully grown Centrosaurus.

Which Dinosaur Made the Feeding Traces?

The researchers ruled out crocodiles, other reptiles and mammals when it came to identifying what creature made the bite marks.  This left the team with three types of Theropod dinosaur to investigate.  Troodontids, Dromaeosaurs and Tyrannosaurs are known from the Dinosaur Provincial Park Formation.  There is also the genus Richardoestesia to consider, its affinity within the Theropoda is uncertain.  The bite marks are too small to have been made by a large Tyrannosaur, but a juvenile Tyrannosaur might have scavenged the carcass.  It is also possible that a dromaeosaurid may have fed on the remains as well.  It is possible that both the dromaeosaurid and a young Tyrannosaur fed on the carcass, after all, modern carcasses may be fed on by multiple species (lions may kill a zebra but hyenas may chase them off the kill and rob them of the carcass – kleptoparasitism).

To read an article from Everything Dinosaur published in 2015 that looks at the structure of the teeth of different Theropod dinosaurs: Research to get your Teeth into

A Hypothesised Reconstruction of a Juvenile Gorgosaurus Feeding on the Carcass of a Juvenile Centrosaurus

A speculative illustration of a young Gorgosaurus feeding on the carcass of a juvenile Centrosaurus.

A young Tyrannosaur (Gorgosaurus) scavenging the carcass of the juvenile Centrosaurus.

Picture Credit: Marie-Hélène Trudel-Aubry/PeerJ

Slim Pickings

The marks on the squamosal fragment represent the first documented case of a carnivore consuming a juvenile ceratopsid, but the trace fossils may represent scavenging a corpse rather than predation.  However, there is not a lot of meat on a squamosal bone.  The scientists suggest that the feeding marks represent late stage consumption, as the most nutritious parts of the young Centrosaurus had already been eaten.  It is possible that a large Tyrannosaur made the kill, fed and then abandoned the carcase which was later picked over by other Theropods.

Despite the apparent preferences for feeding on juvenile dinosaurs, most feeding traces described to date are on the bones of adults which may have resisted being consumed and destroyed (even by large Tyrannosaurs).  Feeding traces on a juvenile dinosaur remain unusual and exceptionally rare.  Perhaps the size and shape of Ceratopsian skulls, even in juveniles, made them difficult to process or required an excess of handling effort for a relatively little reward in terms of food.

The scientific paper: “Bite Marks on the Frill of a Juvenile Centrosaurus from the Late Cretaceous Dinosaur Provincial Park Formation, Alberta, Canada” by David W.E. Hone, Darren H. Tanke and Caleb M. Brown published in PeerJ

13 10, 2018

The Ancestors of Sarahsaurus Probably Did Not Originate in North America

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

Early Jurassic North American Sauropodomorphs were Migrants

The sauropodomorph dinosaur called Sarahsaurus was a migrant into North America just like the other North American sauropodomorphs that have been described to date.  That is the conclusion made by researchers from the University of Texas Austin, in a scientific paper published this week.  Recently, Everything Dinosaur has covered a number of technical papers that have featured the Suborder Sauropodomorpha (the sauropods and their direct ancestors).  The United States might be famous for dinosaurs such as Brontosaurus, Camarasaurus and Diplodocus, but surprisingly not much is known about the ancestors of these iconic, long-necked dinosaurs.  Writing in the open access journal PLOS One, the researchers from the University’s Jackson School of Geosciences, conclude that the handful of sauropodomorphs known from the Lower Jurassic of North America are not that closely related and they represent successive immigration waves into that part of the super-continent Pangaea.

Sarahsaurus and Other North American Early Jurassic Sauropodomorphs Do Not Form a Unique Clade

Sarahsaurus (North American dinosaur).

A life reconstruction of the North American sauropodomorph Sarahsaurus.

Picture Credit: Brian Engh

CT Scans and Phylogenetic Analyses

The researchers conducted the first detailed analysis of the fossils ascribed to the genus Sarahsaurus (Sarahsaurus aurifontanalis).  This dinosaur had been named back in 2010, from fossil material excavated from the Lower Jurassic Kayenta Formation exposed in north-eastern Arizona.  In total, three specimens, including the holotype were studied and subjected to computed tomographic imaging.  With more anatomical data, the scientists then conducted a series of phylogenetic assessments to see where within the Sauropodomorpha Sarahsaurus should be nested and importantly, how the other sauropodomorphs from North America such as Anchisaurus (A. polyzelus) and Seitaad (S. ruessi) were related to Sarahsaurus.

The Main Fossil Block Associated with Sarahsaurus and a Line Drawing Showing a Layout of the Fossil Material

Sarahsaurus holotype.

The main block containing much of the holotype specimen of Sarahsaurus aurifontanalis.

Picture Credit: PLOS One

Sarahsaurus aurifontanalis

All of the Sarahsaurus specimens referred to in this study came from siltstone deposits.  Manual preparation of the fossils was extremely laborious and time consuming.  Many of the bones were encrusted with an extremely hard purple-black oxide coating, hence the use of high-resolution X-ray CT scans to provide more information about the finer details preserved on the fossil material.

In addition, conducting the phylogenetic analysis was made even more problematic than usual as the material used to establish unique characteristics of Sarahsaurus which could then be used to compare with other sauropodomorphs, provided numerous obstacles for the scientists to overcome.  Firstly, a skull used in this study probably came from a much younger individual than the other Sarahsaurus specimens analysed.  Furthermore, not all the specimens shared the same bones so making direct comparisons to establish a unique set of features for Sarahsaurus was challenging.  These factors coupled with some mixing and redistribution of the holotype material in the sediment and the crushed nature of many of the fossil bones made the phylogenetic assessment very tricky, but the researchers were able to conclude that Sarahsaurus aurifontanalis is very probably a member of the Massospondylidae family, which means that this dinosaur is not closely related to the other North American Sauropodomorpha and is more closely related to dinosaurs known primarily from the southern hemisphere (Gondwana).

CT Scans of a Skull Specimen Provisionally Assigned to Sarahsaurus

CT scans help to plot the shape of the fossil skull provisionally assigned to Sarahsaurus.

Skull (MCZ 8893) provisionally referred to Sarahsaurus aurifontanalis, reconstructed from CT data.  Life reconstruction (H) by Brian Engh.

Picture Credit: PLOS One/Brian Engh

Waves of Dinosaur Migration into North America Following the End Triassic Extinction Event

If the three known North American sauropodomorphs are not that closely related and the likes of Sarahsaurus is classified as a member of the Massospondylidae, then this suggests that rather than evolving in North America, these dinosaurs arrived on that part of the super-continent of Pangaea as a result of a number of migrations that took place during the Early Jurassic.  This links with other research that suggests that although Theropods were present in North America during the Triassic transition to the Jurassic, other types of dinosaurs such as the Sauropoda and the Ornithischians populated this part of the world later.

The dinosaurs may not have been the super evolved terrestrial animals that simply outcompeted all the other Tetrapods in the world driving the majority to extinction.  Instead, the Dinosauria may have been opportunists, migrating into areas after the former occupants of key niches in the ecosystem had already died out.

Research Suggests that there were Several Migration Waves into North America During the Early Jurassic

Comparing three North American members of the Sauropodomorpha.

Relative ages of North American sauropodomorphs.

Picture Credit: Everything Dinosaur

To read Everything Dinosaur’s article on the discovery of Seitaad ruessiDinosaur Buried Alive is a New Species from Utah

The scientific paper: “Anatomy and Systematics of the Sauropodomorph Sarahsaurus aurifontanalis from the Early Jurassic Kayenta Formation” by Adam D. Marsh and Timothy B. Rowe published in the open access journal PLOS One.

9 10, 2018

“Powerful Terror Ruler” – Dynamoterror dynastes

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

“Powerful Terror Ruler” – Dynamoterror dynastes

A new species of North American Tyrannosaur has been scientifically named.  The newly described “tyrant lizard” joins a plethora of tyrannosaurids known from the Late Cretaceous of Laramidia, but Dynamoterror dynastes stands out from the majority of these fearsome Theropods for some very important reasons.  Firstly, it is quite geologically old for a Late Cretaceous large-bodied Tyrannosaur, its discovery has implications for our understanding of Tyrannosaur evolution.  In addition, its the frontal bones that help make this dinosaur stand out and besides, its scientific name, which means “powerful terror ruler”, is a nod in the direction of the most famous dinosaur of all – Tyrannosaurus rex.

A Life Reconstruction of Dynamoterror dynastes Attacking the Recently Described Invictarx zephyri

The newly described Tyrannosaur Dynamoterror attacks Invictarx

Dynamoterror ambushes the armoured dinosaur Invictarx zephyri.

Picture Credit: Brian Engh

The Geological Age – Early Campanian

The fossil bones, representing a single, individual animal were collected in 2012.  They herald from San Juan County, New Mexico, specifically the upper part of the Allison Member of the Menefee Formation.  Although fragmentary, the fossil material consists of asociated bones including left and right frontals (bones from the top of the skull over the eye socket), a right metacarpal (bone from the hand), four broken pieces from the backbone, pieces of rib, a portion of the right ilium and some toe bones, plus several unidenfiable slithers of bone.  It might not sound like much, but this is the first associated tyrannosaurid skeleton reported from the Menefee Formation.  Isolated teeth had been found in this locality before suggesting the presence of tyrannosaurids, but Dynamoterror dynastes is the first to be named and described.  It was probably the dominant predator in the lush, tropical, coastal swamps that covered this part of the southern United States some 80 million years ago.

During the Late Cretaceous, North America was essentially split into two by a wide seaway, the Western Interior Seaway.  To the east lay Appalachia and Tyrannosaurs are known from here, but not many, only two genera have been named to date – Appalachiosaurus montgomeriensis and Dryptosaurus aquilunguis and both of these are only known from a single, partial, associated skeleton.  In the Upper Cretaceous strata to the west that formed the landmass called Laramidia, lots of Tyrannosaurs have been named and described.  However, the tyrannosaurid record for Laramidia is restricted to a period from about 77 million years ago to the K-Pg extinction event some 66 million years ago.  Dynamoterror comes from rocks which are around 3 million years older.  It provides the first fossil record of a Laramidian tyrannosaurid from the Early Campanian of 80 million years ago and, as a result, will help palaeontologists to better understand tyrannosaurid evolution.

The Cool Thing About Frontals

Less than one percent of the skeleton may have been found (field teams were despatched in 2013 and again this year to try and find more remains but without luck), but when it comes to describing a new genus, it is often quality that triumphs over quantity.  The frontal bones, their shape, the groves that they possess and other features including how they knit together with other skull bones, can prove extremely helpful when it comes to identifying a new dinosaur species.  The researchers which included Dr Andrew McDonald (Curator, of the Western Science Centre, California), identified some unique characteristics in the frontal bones, hence the establishment of a new genus.

Photographs and Computer-generated Three-dimensional Models of the Left and Right Frontals of D. dynastes

The frontal bones of Dynamoterror dynastes.

Photographs and three-dimensional, computer-generated models of the right frontal (A, B) and the left frontal (C, D) of Dynamoterror dynastes (rostal view – viewed from the front of the brain).  Scale bar = 5  centimetres.

Picture Credit: PeerJ/Western Science Centre

A Large Bodied Tyrannnosaur

The researchers cannot be certain whether their fossil discovery represents a fully grown animal or a sub-adult.  However, when the frontal bones of D. dynastes were compared to those of Tyrannosaurus rex, the scientists concluded that Dynamoterror was at least nine metres long.  The armoured dinosaur that features in the illustration (above), Invictarx, was also named and described by Dr McDonald, along with Mr Doug Wolfe (Zuni Dinosaur Institute for Geosciences) who worked together on this Tyrannosaur.  It is likely that more dinosaurs will be described based on fossil discoveries from within the Menefee Formation.  Alton C. Dooley Jr also collaborated in the study of Dynamoterror.

To read about the discovery of the nodosaurid Invictarx: A New Nodosaur from New Mexico

Size Comparison of Selected Late Cretaceous Tyrannosaurs

Comparing the size of selected Late Cretaceous Tyrannosaurs.

Size comparison between selected Late Cretaceous Tyrannosaurs.

Picture Credit: Everything Dinosaur

What’s in a Name?

This new taxon provides further, significant insight into the morphology and diversity of tyrannosaurids from the Early Campanian of Laramidia and it’s name is pretty cool too.  The genus name is taken from the Greek word “dynamis” which means “power” and the Latin word “terror”.  The trivial or specific name, is from the Latin word “dynastes” meaning “ruler”.  Hence, the binomial scientific name Dynamoterror dynastes translates to “powerful terrror ruler”, however, the scientific paper also states that this epithet honours the name “Dynamosaurus imperiosus“, from Henry Fairfield Osborn, the American palaeontologist who referred to fossil material later assigned to Tyrannosaurus rex as Dynamosaurus imperiosus in scientific papers published in the early years of the 20th Century.

The Reconstructed Frontal Complex of Dynamoterror dynastes

Life restoration of the frontals of Dynamoterror dynastes.

The reconstructed frontals of D. dynastes.

Picture Credit: PeerJ/Western Science Centre

In the picture above, the left and right frontals have been articulated together to show how they would sit at the top of the skull, in (A) rostral; (B) caudal; (C) right lateral; (D) dorsal; and (E) ventral views.   The illustration (F), shows a view of the reconstructed skull in dorsal view.  Individual bone elements of the skull are colour-coded to show how the top of the skull knitted together: frontals (grey); fused nasals (violet); prefrontals (yellow); lacrimals (red); postorbitals (blue); and parietal (green).  The scale bars represent 5 centimetres and the missing skull bones have been based on the related tyrannosaurid Teratophoneus curriei, a geologically younger Tyrannosaur from the Upper Campanian of southern Utah (Kaiparowits Formation).  T. curriei roamed Laramidia around 76 million years ago, some 4 million years after Dynamoterror dynastes.

The scientific paper: “A New Tyrannosaurid (Dinosauria: Theropoda) from the Upper Cretaceous Menefee Formation of New Mexico” by Andrew T. McDonald, Douglas G. Wolfe and Alton C. Dooley published in PeerJ

29 09, 2018

New Giant Dinosaur From South Africa Described

By | September 29th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Ledumahadi mafube – Giant Plant-eater from the Early Jurassic

A new species of giant sauropodiform from the Early Jurassic of South Africa has been named and described. The dinosaur has been named Ledumahadi mafube and is estimated to have weighed around twelve tonnes and stood about four metres high at the hips. L. mafube may have been the largest animal alive on Earth between 200 and 195 million years ago.  Over the course of the Jurassic, gigantic Sauropod genera evolved, famous giants such as Brontosaurus, Brachiosaurus and Diplodocus.  Writing in the journal “Current Biology”, the international research team led by Professor Jonah Choiniere (Witwatersrand University), concluded that Ledumahadi shows that quadrupedal sauropodomorphs which lacked the columnar limbs of the later Sauropods could still attain, massive Sauropod-like body sizes.  This challenges one of the assumptions held in palaeontology, that the evolution of column-like legs was a prerequisite that enabled the long-necked, lizard-hipped dinosaurs to grow so big.

A Life Reconstruction of the Newly Described Sauropodiform Ledumahadi mafube

Ledumahadi mafube illustrated.

A life reconstruction of Ledumahadi mafube.

Picture Credit: Viktor Radermacher (Witwatersrand University)

The illustration shows the twelve tonne South African giant Ledumahadi mafube with its bent, semi-erect forelimbs.  It is observed by a much smaller Early Jurassic dinosaur, the Ornithischian Heterodontosaurus tucki.

“Giant Thunderclap at Dawn”

The fossil material consists of disarticulated post-cranial material discovered at Beginsel farm, approximately fifteen miles southeast of the town of Clarens in Free State Province, close to the border of South Africa and Lesotho.  The fossils were found in mudstone from the upper Elliot Formation representing terrestrial sediments laid down between 200 and 195 million years ago (Hettangian to Sinemurian faunal stages of the Early Jurassic).

The Fossilised Remains of Ledumahadi mafube and Location Maps

Fossils and location map of Ledumahadi mafube (South Africa).

Skeletal drawing the fossils of Ledumahadi mafube along with maps showing the fossil discovery location (UEF – upper Elliot Formation, whilst LEF – lower Elliot Formation).

Picture Credit: Witwatersrand University

The dinosaur’s name, pronounced Le-dew-ma-har-dee maf-fu-be is from the local Sesotho dialect of the region.  It translates as “giant thunderclap at dawn”, reflecting the size of the animal and the stratigraphically early position of this taxon.

Commenting on the significance of the name, Professor Choiniere stated:

“The name reflects the great size of the animal as well as the fact that its lineage appeared at the origins of Sauropod dinosaurs.   It honours both the recent and ancient heritage of southern Africa.”

Fossil Bones Photographed at the Quarry Site

Giant dinosaur bones from South Africa

Bones from the front limbs (hands) – Ledumahadi mafube, the penknife provides a handy scale.

Picture Credit: Witwatersrand University

An Adult Dinosaur Around Fourteen Years Old When it Died

An analysis of the growth lines of the limb bones indicate that the specimen was fully grown when it died and that this dinosaur was approximately fourteen years old when it met its demise.  The research team compared the limb measurements of the front and hind limbs of Ledumahadi with other dinosaurs and extant Tetrapods and they concluded that this dinosaur, had very robust limbs and was a quadruped, which weighed around twelve tonnes.  The plant-eating Ledumahadi was a giant amongst the Early Jurassic Dinosauria, it is the largest animal known so far from Early Jurassic sediments more than 195 million years old.  When Ledumahadi roamed it may have been the largest animal on Earth at the time.

Professor Choiniere and the Distal Portion of the Right Femur of Ledumahadi

Professor Jonah Choiniere describes the new Early Jurassic dinosaur Ledumahadi mafube.

Professor Jonah Choiniere with the distal portion of the femur of Ledumahadi.

Picture Credit: Witwatersrand University

A Different Stance and Posture Compared to Later Sauropods

The scientists, which included Roger Benson from Oxford University, conclude that L. mafube had a different posture than later Sauropods.  It did not have the column-like limbs of dinosaurs like Brontosaurus, Brachiosaurus and Diplodocus, its forelimbs would have been more crouched and partially flexed.  The research team postulate that this posture was an evolutionary experiment with gigantism within the lizard-hipped reptiles.

Lead author of the paper, Dr Blair McPhee (Witwatersrand University), explained:

“The first thing that struck me about this animal is the incredible robustness of the limb bones.  It was of similar size to the gigantic Sauropod dinosaurs, but whereas the arms and legs of those animals are typically quite slender, Ledumahadi’s are incredibly thick.  To me this indicated that the path towards gigantism in sauropodomorphs was far from straightforward and that the way that these animals solved the usual problems of life, such as eating and moving, was much more dynamic within the group than previously thought.”

Professor Choiniere Compares A Giant Toe Claw Bone (Pedal Ungual) with His Hand

The toe claw (ungual) of Ledumahadi mafube.

Professor Jonah Choiniere holding a pedal ungual (toe claw bone) from Ledumahadi mafube.

Picture Credit: Witwatersrand University

A Transitional Form of Long-necked Dinosaur

Analysis of the bones and comparative studies with other Sauropods and extant Tetrapods, led the scientists to conclude that the internal structure of the bones of Ledumahadi displayed traits associated with basal sauropodomorphs and more derived members of this group.  L. mafube probably represents a transitional stage between the sauropodomorphs and the later true Sauropoda.

Limb Bone Study Has Helped Plot the Evolutionary Change from Bipedalism to a Quadrupedal Stance

How did a quadrupedal stance in Sauropods evolve?

Plotting the evolutionary change from bipedalism to a quadrupedal stance in the Sauropoda.

Picture Credit: Witwatersrand University

The picture above depicts silhouettes scaled in height to the cube root of mass estimate of the taxon.  The colour of the silhouettes represents the inferred posture; red is bipedal, and black equals quadrupedal.   The purple line marks the Triassic/Jurassic boundary.

Out-competed by the Columnar-limbed Sauropods

Ledumahadi may have been the biggest animal on Earth during the very Early Jurassic, but the fossil record indicates that this large dinosaur body-plan with flexed limbs and a more crouched posture was not to last.  Co-existing with Ledumahadi were primitive Sauropods such as Vulcanodon (V. karibaensis), which although smaller had column-like limbs.  Within a few million years, only the columnar-limbed Sauropods remained as the only surviving lineage.  The reasons for this faunal turnover are unclear, but it might reflect that Ledumahadi might have had to expend more energy moving about with its flexed limbs that were not held directly under the body.  The more energy efficient posture of the straight-legged Sauropods with their column-like legs may have provided a competitive edge, driving dinosaurs like Ledumahadi to extinction.

To read Everything Dinosaur’s article about a recently described long-necked, Early Jurassic sauropodiform from China that is also helping palaeontologists to better understand Sauropod evolution:  Yizhousaurus Helping to Give Sauropod Evolution a Head Start

The scientific paper: “A Giant Dinosaur from the Earliest Jurassic of South Africa and the Transition to Quadrupedality in Early Sauropodomorphs” by Blair W. McPhee, Roger B.J. Benson, Jennifer Botha-Brink, Emese M. Bordy & Jonah N. Choiniere published in the journal “Current Biology”.

26 09, 2018

Bird Evolution Very Complicated

By | September 26th, 2018|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Jinguofortis perplexus – A Mosaic of Dinosaur and Bird Features

Scientists from the Chinese Academy of Scientists have described a new species of ancient, Early Cretaceous bird with a mosaic of dinosaur and bird characteristics.  The bird, which has been named Jinguofortis perplexuslived approximately 127 million years ago and it will help palaeontologists to learn more about bird development and the evolution of powered flight in the avian dinosaurs.

An Illustration of the Newly Described Early Cretaceous Bird Jinguofortis perplexus

Jingoufortis perplexus illustrated.

Jinguofortis a newly described Early Cretaceous bird with a mosaic of avian and reptilian traits.

Picture Credit: PNAS (Chung-Tat Cheung)

The pigeon-sized bird does not have a long bony tail, a characteristic inherited from dinosaurs that is found in the first birds such as Archaeopteryx.  Instead, the tail is much reduced and ends with a compound bone, a pygostyle, possessed by modern birds today.  Jinguofortis perplexus represents a transitional form, after birds had lost their dinosaurian tails but before they had evolved a fan of flight feathers on their shortened, compressed tails.

Honouring the Contribution of Female Scientists

The fossil specimen comes from the Debeigou Formation of north-eastern China and the genus name “Jinguofortis” derives from the Mandarin word for female warrior “jinguo” and the Latin word “fortis” meaning brave and strong.  The name honours the contribution made to palaeontology by female scientists around the world.  The species or trivial name “perplexus” is from the Latin and reflects the puzzling mix of anatomical traits.  Jinguofortis has been assigned to a basal member of the clade of short-tailed birds (Pygostylia).

The Slab and Counter Slab of the Fossil Bird Jinguofortis perplexus

Jingoufortis perplexus fossil material.

The fossilised remains of the Early Cretaceous bird Jinguofortis perplexus.

Picture Credit: PNAS (Proceedings of the National Academy of Science)

Avian and Dinosaurian Characteristics

Writing in the academic journal “Proceedings of the National Academy of Sciences (USA)”, the researchers Wang Min, Thomas Stidham and Zhou Zhonghe (Chinese Academy of Sciences), describe a unique combination of anatomical traits, including a jaw with small teeth like Jinguofortis’s Theropod dinosaur relatives as well as a short bony tail ending in a pygostyle.  Gizzard stones associated with the well-preserved, but rather flattened fossil, indicate that Jinguofortis may have fed on seeds and other plant material.  Jinguofortis also possessed a third finger with only two bones, unlike other early birds.

Fused Shoulder Bones

Close examination of the slab and counter slab revealed that the shoulder girdle of Jinguofortis was fused into a single bone, the scapulocoracoid, a feature associated with the non-avian dinosaurs.  Modern birds usually have two bones the scapula and the coracoid that provide greater flexibility in the shoulder, ideal for flapping, powered flight.  The fossil’s shoulder joint also gives clues about its flight capacity.  In flying (volant) birds, the shoulder, which experiences high stress during flight, is a tight joint between the two unfused bones (scapula and the coracoid).  In contrast, Jinguofortis perplexus with its fused bones suggests that it flew in a different way compared to modern birds.

Changes in the Coracoid and Scapula (Shoulder Girdle) in Vertebrates

Evolution of the shoulder girdle with a focus on the Avialae.

Changes in the evolution of the shoulder girdle (vertebrates) and the development of the shoulder within Avialae.

Picture Credit: Wang Min (Chinese Academy of Sciences)

The picture above plots the main changes in the shoulder joint of vertebrates from fish through to Tetrapods such as amphibians, reptiles and mammals.  The second part of the diagram maps the evolution of the shoulder joint from the Dromaeosauridae (the raptors), through to avian dinosaurs (birds) and shows that Jinguofortis sits between the earlier Confuciusornithiformes and the later Sapeornithiformes and is basal to the Pygostylia.  The diagram provides a temporal reference and also illustrates the evolution of the bird hand with its much reduced digits from dinosaurian ancestors with their grasping hands.

Measurement of the fossil’s wing size and estimation of its body mass show that the extinct species had a wing shape and wing loading (wing area divided by body mass) similar to living birds that need a lot of manoeuvrability.  Jinguofortis lived in a dense forest.  Its body plan would have assisted it to dodge and weave through the branches and dense foliage as it flew.

Jinguofortis perplexus with its mosaic of bird and dinosaur characteristics suggests that the evolution of modern birds was more complex than previously thought.

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