Phuwiangvenator yaemniyomi and Vayuraptor nongbualamphuensis

Two new species of theropod dinosaur have been described from partial fossil remains excavated from strata associated with the Sao Khua Formation of north-eastern Thailand.  It is likely that both these meat-eating dinosaurs have affinities with the Megaraptora and their discovery lends weight to the idea that the Megaraptoridae and their near relatives probably originated in Asia.

The dinosaurs have been named Phuwiangvenator yaemniyomi and Vayuraptor nongbualamphuensis, Phuwiangvenator has been described as a megaraptoran whilst the exact taxonomic position of Vayuraptor remains uncertain, although the authors of the scientific paper suggest that it too was a member of the clade of dinosaurs with long-snouts, highly pneumatised skeletons and with large claws.

Bones in Approximate Life Position from the Right Foot of P. yaemniyomi

Picture credit: Samathi et al

Lower Cretaceous Theropod Dinosaurs

The fossils were found nearly twenty-five miles apart, but the strata in which the fragmentary fossil material was found is contemporaneous and dated to the upper Barremian stage of the Lower
Cretaceous.

The first identified specimens of P. yaemniyomi were found by Preecha Sainongkham, a team member at the Phu Wiang Fossil Research Centre and Dinosaur Museum back in 1993.  The Phu Wiang Mountain region is highly fossiliferous and numerous vertebrate fossils representing the fauna of a low-lying, inland, lacustrine environment have been discovered over the years.  The first dinosaur bone known from Thailand was found in 1976, a scrappy bone fragment that was assigned to the Sauropoda.  This fossil was found by Sudham Yaemniyom, who was at the time a geologist with the country’s Department of Mineral Resources, Bangkok.  The species name of Phuwiangvenator yaemniyomi honours his contribution to the geology and palaeontology of Thailand.

Phuwiangvenator is the larger of the two theropods, it is believed to have measured around 5.5 to 6 metres in length.  It is known from dorsal and sacral vertebrae plus elements of the hind limbs and feet.  All the fossil material was found within the same bedding plane and within an area of just 5 square metres.

Views of the Right Tibia (A1 – A6) and a Proximal View of the Left Tibia (P. yaemniyomi)

Picture credit: Samathi et al

Vayuraptor nongbualamphuensis – Raptor of the Wind God

The fossils associated with Vayuraptor were found in 1988.  It is known from a left tibia and ankle bones.  The genus name is from the Sanskrit for “Vayu”, a God of the Wind and the Latin term “raptor”, which means thief.  Analysis of the single lower leg bone indicates that like Phuwiangvenator, this dinosaur was a fast-running, cursorial predator.  The fossils of both dinosaurs are now part of the extensive dinosaur fossil collection at the Sirindhorn Museum in Kalasin Province.  This museum houses the largest collection of dinosaur fossil bones in north-eastern Thailand.

Analysis of the Tibia Suggests that Vayuraptor was a Fast Runner

Picture credit: Samathi et al

Megaraptora Originated in Asia

The establishing of at least one of these dinosaurs as a member of the Megaraptora clade, possibly both, helps to support the hypothesis that in south-eastern Asia during the Early Cretaceous, it was the Megaraptora that were diverse and playing the role of apex predators.  This is in contrast to other ecosystems elsewhere in the world, that were dominated by different kinds of theropod dinosaur.  A basal member of the Megaraptora, Fukuiraptor kitadaniensis is known from the Lower Cretaceous (Barremian) of Japan, these two dinosaurs are also (most likely), from the Barremian.  Their identification supports the idea that these fast running, lightly built predators evolved in Asia.

A Model of the Basal Megaraptoran  Clade – Fukuiraptor

The picture (above) features a CollectA Fukuiraptor model.

To view the range of not-to-scale CollectA prehistoric animals: CollectA Prehistoric Life Models and Figures.

An Early Cretaceous Heyday for the Megaraptorans

Fossils of this type of meat-eating dinosaur have been reported from the Barremian to the Aptian faunal stage of the Early Cretaceous.  The authors of the scientific paper, published in the scientific journal “Acta Palaeontologica Polonica”, note that several specimens of megaraptoran dinosaurs have been recorded from the Aptian of Australia and one reported from the later Albian faunal stage of South America.  Megaraptorans are known from the Late Cretaceous but seem to indicate that by around 90 million years ago, “megaraptors” had a more limited range and seem to have been confined mostly to South America.

A Typical Illustration of a Member of the Megaraptoridae Family of Theropod Dinosaurs

Picture credit: Jan Sovak (University of Alberta)

Commenting Upon the Theropod Dinosaurs

A spokesperson from Everything Dinosaur commented:

“The identification of these theropod remains that had been known about for more than twenty-five years, has been partially resolved.  Hopefully, more fossil material associated with the Vayuraptor genus will be found in Thailand so that it too can be more definitively placed within the Megaraptora clade.  Given the extent of the fossil discoveries made from the Phu Wiang Mountain region thus far, it is highly likely that more new dinosaurs will be named and described from Thailand in the future.”

To read an article about a Late Cretaceous member of the Megaraptoridae family from South America that was reported upon in 2018: A New Member of the Megaraptoridae from the Late Cretaceous of South America (Tratayenia rosalesi).

The scientific paper: “Two new basal coelurosaurian theropod dinosaurs from the Lower Cretaceous Sao Khua Formation of Thailand” by A. Samathi, P. Chanthasit and P. Martin Sander published in  Acta Palaeontologica Polonica.

Visit the Everything Dinosaur website: Everything Dinosaur.

Mussaurus Switched from Four Legs to Two

A team of scientists, including researchers from the Royal Veterinary College based in London and Museo de La Plata and National Scientific and Technical Research Council (CONICET) located in Argentina, have collaborated to produce a report on how a Late Triassic sauropodomorph changed as it grew up.

The dinosaur in question Mussaurus patagonicus is an ideal candidate for dinosaur growth studies as it is known from numerous partial to nearly complete skeletons from hatchlings to fully grown adults.  Writing in the academic journal the researchers conclude that Mussaurus could only move on four limbs once born but switched to two legs as it grew up, just as our species switches from all fours to bipedal walking as we grow.

Scientists Looked at How the Centre of Mass Changed in the Body of Mussaurus to Work Out How it Walked

Picture credit: Scientific Reports

An Argentinian Sauropodomorph

Fossils of Mussaurus come from southern Argentina, at birth this dinosaur was only a few centimetres in length, but it reached its adult size in around eight years.  Essentially, this dinosaur went from weighing about 60 grams to weighing an estimated 1,300 kilograms with a body length of approximately 8 metres.  The research team conclude that it might have barely been able to walk or run on two legs at the age of one, but would have only committed to being bipedal once it reached adulthood.

This study has implications for the largest terrestrial vertebrates that ever lived as Mussaurus is regarded as an ancestral form of the later sauropods, giants like Apatosaurus, Mamenchisaurus and Giraffatitan, that were to evolve in the Jurassic.

The team scanned key fossils of Mussaurus into three-dimensional models, connected the bones into digital skeletons, and added soft tissue to estimate the shape of the body and its major segments such as head, neck, torso, tail and limbs.  These computer models were then used to estimate the location of the animal’s centre of mass, the point at which all weight can be assumed to act through.  This estimate enabled the scientists to then test whether different models representing different growth stages of Mussaurus patagonicus could have stood on two legs or not, because the centre of mass must be placed under the feet in such poses.

Identifying the Centre of Mass as Mussaurus Grew Up

Picture credit: Scientific Reports

Baby Dinosaurs – From Four Legs to Two

One of the authors of the scientific paper, Dr Alejandro Otero (CONICET) stated:

“Mussaurus switched from four legs as a baby to two legs by adulthood, much as humans do.  It is important to notice that such locomotor switching is rare in nature and the fact that we were able to recognise it in extinct forms like dinosaurs highlights the importance of our exciting findings.”

Professor John Hutchinson of the Royal Veterinary College, an expert in animal locomotion and co-author of the paper commented:

“We created the first 3-D representation of the major changes of body form and function across the growth of a dinosaur.  And we were surprised to learn that enlargement of the tail and reduction of the neck had more of an effect on how Mussaurus stood than how long its forelimbs were, which is what people used to think.”

Implications for Giant Dinosaurs

At around eight metres in length, Mussaurus was one of the largest dinosaurs in southern South America during the Late Triassic (estimated to be Norian faunal stage), however, during the Jurassic and Cretaceous much larger lizard-hipped dinosaurs would evolve from this lineage.  By improving our understanding about how some of the sauropodomorphs moved this type of research can provide insights into how much bigger plant-eating, long-necked giants walked.  When adult, dinosaurs such as Diplodocus and Brachiosaurus were very much quadrupedal, although it has been suggested that when very young some of these dinosaurs might have been able to rear up onto their hind legs to escape danger.*

Mussaurus Scale Comparison

Picture credit: Scientific Reports with additional annotation and information from Everything Dinosaur

* To read an article from 2011 that looked at the research into trace fossils from the western United States that hinted that some very young sauropods may have been able to run on just their hind legs: Facultative Bipedalism in Sauropods.

The research team hope to build on this work as they plan to use computer models to replicate in greater detail how Mussaurus may have actually moved, such as how fast it could walk or run.

Everything Dinosaur acknowledges the assistance of a press release from the Royal Veterinary College (London) in the compilation of this article.

The scientific paper: “Ontogenetic changes in the body plan of the sauropodomorph dinosaur Mussaurus patagonicus reveal shifts of locomotor stance during growth” by Alejandro Otero, Andrew R. Cuff, Vivian Allen, Lauren Sumner-Rooney, Diego Pol and John R. Hutchinson published in Scientific Reports.

Visit the Everything Dinosaur website: Everything Dinosaur.

Ancient Mouse Reveals a Colourful Mammalian Heritage

Many mammals are brightly coloured, we have golden marmosets, red pandas and of course, black and white zebras.  The evolutionary use of colour within the Kingdom Animalia has long held the fascination of scientists, academics and philosophers.  This week, an international team of researchers led by members of The University of Manchester have published a new study revealing the evidence of colourful pigments in the remains of an ancient mouse.

The Fossilised Remains of a Prehistoric Mouse

Picture credit: The University of Manchester

Establishing the Colouration of Extinct Animals

Writing in the journal “Nature Communications”, this work marks a major breakthrough in our ability to define colour pigments within the fossilised remains of long extinct animals and emphasises the role colour plays in the evolution of life on our planet.  The paper entitled “Pheomelanin pigment remnants mapped in fossils of an extinct mammal”, outlines the use of X-ray imaging on the 3 million-year-old fossils in order to unravel the story of key pigments in ancient creatures and demonstrates how we might recognise the chemical signatures of specific red pigments in extinct animals to determine how they evolved.

Professor Phil Manning, (University of Manchester), the lead palaeontologist involved in this study explained:

“The fossils we have studied have the vast potential to unlock many secrets of the original organism.  We can reconstruct key facets from life, death and the subsequent events impacting preservation before and after burial.  To unpick this complicated fossil chemical archive requires an interdisciplinary team to combine their efforts to crack this problem.  In doing this, we unlock much more than just palaeontological information.”

Co-author, Professor Roy Wogelius, from the University’s School of Earth and Environmental Sciences, added:

“This was a painstaking effort involving physics, palaeontology, organic chemistry, and geochemistry.  By working as a team, we were able, for the first time, to discover chemical traces of red pigment in fossil animal material.  We understand now what to look for in the future and our hope is that these results will mean that we can become more confident in reconstructing extinct animals and thereby add another dimension to the study of evolution.”

This exciting, collaborative effort from numerous scientific disciplines reveals that within fossils with exceptionally preserved soft tissues, evidence of black pigmentation can be identified, but furthermore, traces of the much more elusive red animal pigment may be found.  The chemical residue of black pigment, which colours such animals as crows, was first resolved by this team in a previous study nearly ten years ago.  However, the red pigment, characteristic of animals such as foxes and red pandas, is far less stable over geological time and proved much more difficult to detect.

Apodemus atavus Life Reconstruction

Picture credit: The University of Manchester

Professor Wogelius went on to say:

“We had data which suggested red pigment residue was present in several fossils, but there was no useful data available to compare this to pigmentation in modern organisms.  So, we needed to devote several years to analysing modern tissue before we could go back and review our results from some amazing fossil specimens.  In the end, we were able to prove that detailed chemical analysis can resolve such pigment residue, but along the way we learned so much more about the chemistry of pigmentation throughout the animal kingdom.”

Shining a Light on Pigmentation Thanks to the Stanford Synchrotron Radiation Lightsource

To unlock the hidden data within the ancient mouse fossil material, the Manchester-based scientists collaborated with researchers at some of the brightest sources of light on the planet, using synchrotron radiation at the Stanford Synchrotron Radiation Lightsource (USA), and also at the Diamond Light Source (located in Oxfordshire), to bombard the fossils with intense X-rays.  It is the interaction of these X-rays with the chemistry of these fossils that enabled the team to be the first to recognise the chemistry of red pigmentation (pheomelanin), in fur from the exceptionally well-preserved remains of a mouse that scuttled about in the Pliocene Epoch (Apodemus atavus).

The key to the study was identifying trace metals incorporated by ancient organisms into their soft tissues and comparing these to the modes of incorporation into living species.  The chemistry shows that the trace metals in the mouse fur are bonded to organic chemicals in exactly the same way that these metals are bonded to organic pigments in animals with high concentrations of red pigment in their tissue.

In order to confirm the team’s findings, modern comparison standards were analysed by synchrotron radiation and by specialists in pigment chemistry based at the Fujita Health University in Japan.

A False Colour Image of the Fossilised Mouse

Picture credit: The University of Manchester

Ancient Mouse Provides Insights into Many Scientific Disciplines

Summarising the significance of this research Professor Manning stated:

“Palaeontology offers research that is more than relevant to our everyday life.  Information gleaned from the fossil record is influencing multiple fields, including; climate research, the burial of biowaste and radwaste, the measure of environmental impact of oil spills on living species with techniques developed on fossil organisms.  Whilst our research is firmly anchored in the past, we set our sights on its application to the future.”

The scientific paper: “Pheomelanin pigment remnants mapped in fossils of an extinct mammal” by Phillip L. Manning, Nicholas P. Edwards, Uwe Bergmann, Jennifer Anné, William I. Sellers, Arjen van Veelen, Dimosthenis Sokaras, Victoria M. Egerton, Roberto Alonso-Mori, Konstantin Ignatyev, Bart E. van Dongen, Kazumasa Wakamatsu, Shosuke Ito, Fabien Knoll & Roy A. Wogelius and published in Nature Communications

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

Visit the Everything Dinosaur website: Everything Dinosaur.