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

30 05, 2019

Two New Theropod Dinosaurs from Thailand

By | May 30th, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

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

Bones from the foot of Phuwiangvenator yaemniyomi.

Bones and claws from the right foot of Phuwiangvenator yaemniyomi with an accompanying line drawing.

Picture Credit: Samathi et al

Lower Cretaceous Carnivorous 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)

Phuwiangvenator yaemniyomi bones from the lower leg.

Right tibia (A) in various views with a proximal view (B) of the left tibia – Phuwiangvenator 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

Ankle and lower leg bone Vayuraptor.

Vayuraptor nongbualamphuensis views of the left tibia and ankle (A5 and A6).

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

CollectA Fukuiraptor dinosaur model.

CollectA Fukuiraptor model.  It is likely that Phuwiangvenator yaemniyomi and Vayuraptor nongbualamphuensis were similar to Fukuiraptor kitadaniensis.

Picture Credit: Everything Dinosaur

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

Roaming Patagonia 80 million years ago

A leggy, Late Cretaceous carnivore (Murusraptor).  Roaming Patagonia around 80 million years ago.  By the Late Cretaceous the Megaraptoridae may have been less widespread and more provincial.

Picture Credit: Jan Sovak (University of Alberta)

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.

26 05, 2019

Some Baby Dinosaurs Crawled Before Learning to Walk on Two Legs

By | May 26th, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

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

Plotting changes in Mussaurus as it grew.

Mussaurus specimens. (a, b) hatchling, (c) yearling and (bottom) adult.  Scale bars represent 5 cm (a), (b) 15 cm (c) and 100 cm in the adult animal representation.

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

Mussaurus Locomotion Study

Plotting the ontogeny of Mussaurus (a) hatchling, (b) yearling and (c) adult animal and the subsequent effect on centre of mass and locomotion.

Picture Credit: Scientific Reports

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

Mussasaurus scale comparison.

Mussaurus scale drawing compared to an adult human and the skeleton of a typical Late Jurassic sauropod.

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.

23 05, 2019

Ammonite Shell Preserved in Amber from Myanmar

By | May 23rd, 2019|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Ammonite Trapped in Nodule Helps to Date Myanmar Amber Fossils

This month has seen the publication of yet another remarkable paper detailing fossil discoveries found within amber nodules from northern Myanmar.  Writing an open article in the PNAS (Proceedings of the National Academy of Sciences of the United States of America), the researchers document a variety of terrestrial and marine invertebrates consisting of molluscs, insects, spiders and mites that have been preserved trapped in a piece of fossilised tree resin that dates from around 99 million years ago.  The organic remains consist of a mixed assemblage of intertidal and terrestrial floor organisms and suggests that the Cretaceous Myanmar forest was adjacent to a shifting and dynamic coastal environment.  The identification of the ammonite at the genus level has permitted the researchers to provide supporting evidence as to the age of the amber.  The ammonite shell is a juvenile Puzosia and its discovery adds weight to those academics proposing the dating of the amber to Late Albian–Early Cenomanian.

The Amber Nodule (Myanmar) with the Preserved Invertebrate Remains

Amber nodule preserves both terrestrial and marine organisms.

The amber nodule from Myanmar with a wide variety of both marine and terrestrial elements preserved within it.  The ammonite can be seen on the right of the picture, one of the gastropods is directly above it.

Picture Credit: PNAS

This is a rare example of a marine organisms associated with tree resin and also represents a rare instance of the dating of fossil tree resin using the remains of organisms trapped within an amber nodule.

X-ray-microcomputed Tomography (CT) Scans

The amber from northern Myanmar has provided palaeontologists with some fascinating fossils to study, including feathers, baby birds and even the partial tail of a feathered dinosaur.  The amber nodule in this study (BA18100), was obtained from an amber mine close to Noije Bum Village, Tanaing Town and it weighs a fraction over six grams.  Measuring 33 mm long, 9.5 mm wide and 29 mm high, it contains a diverse assemblage of at least forty individuals.  X-ray-microcomputed tomography (CT) scans was employed to help identify the fossil material.

Specimens from the Amber Nodule (BA18100)

A variety of invertebrates preserved in the amber nodule.

Mites, insects including flies and cockroaches and a spider preserved in the amber nodule.

Picture Credit: PNAS

The Ammonite Remains

The ammonite appears to be a juvenile and from a review of the septa (the complex boundary lines outlining the chambers), it has been identified as a member of the Puzosia genus.  This type of ammonite is known from the Cretaceous of the western Tethys Ocean, these fossils help to support the fossil record for this genus from the eastern Tethys region.  The ammonite has a diameter of around 12 mm and it appears to retain its original aragonite shell, that is the shell has not undergone any mineral replacement as expected during fossilisation.  The shell is almost complete, only the final body chamber is damaged as part of the umbilical wall extends beyond the fragmentary last part of the shell.

Views of the Ammonite Preserved within the Amber

Ammonite shell preserved in amber.

The juvenile ammonite has been identified as being from the Puzosia genus, it helps to date the amber nodule.  Scale bars equal 2 mm.

Picture Credit: PNAS

Marine Snail Shells (Gastropods)

The amber also contains the remains of marine snails.  Two of the gastropods have been identified as the genus Mathilda.  This type of marine snail is known from the western Tethys Ocean, but this is the first time that this marine snail genus has been recorded from the eastern Tethys.  The incomplete preservation and lack of soft body of the ammonite and marine gastropods suggest that they were dead and underwent abrasion on the seashore before entombment within the tree resin.

Views of the Marine Snail Shells (Gastropods)

Marine gastropods preserved in an amber nodule.

Four marine snails (gastropods) preserved in the amber of which two definitely represent the genus Mathilda.  Scale bars equal 1 mm.

Picture Credit: PNAS

Isopods

At least four isopods are also present.  Isopods are crustaceans and these creatures are known from terrestrial, brackish, freshwater as well as marine environments.  Unfortunately, the researchers were not able to identify the remains to the extent whereby it could be determined whether the preserved individuals came from the land or were aquatic.

Isopods Preserved within Amber

Isopods preserved in amber from Myanmar.

Four isopods and possibly three other specimens preserved in the amber that could be isopods but they are too badly damaged to be certain.  It is also not certain whether the isopods represent terrestrial, intertidal or marine forms.  Scale bars, 1 mm in A and C.  Scale bar, 0.5 mm in B and D.

Picture Credit: PNAS

How Did the Marine Assemblage End Up in the Tree Resin?

The scientists conclude that the tree resin fell onto the beach from coastal trees, for example araucarian conifers could have been growing close to the shore and the resin originated from one of these trees.  As it slid down the tree trunk it picked up terrestrial creatures and under gravity is moved across the sand picking up the shells on the beach.  It is remarkable that the tree resin survived the high-energy shore environment before being preserved as amber.  The authors, which include scientists from the Chinese Academy of Sciences suggest that resin ending up on the beach due to the proximity of the conifers could have been a relatively common event.  However, since this is the first time that an ammonite shell has been discovered entombed, the odds of fossilisation occurring and the material surviving long enough to turn into amber marks an exceptionally rare occurrence.

The dating of amber can be extremely difficult as these pieces can be reworked and redeposited.  The finding of an ammonite within a nodule, provides biostratigraphical dating support attesting to the 99-100 million-year-old estimate for these types of ancient tree resin from northern Myanmar.

The scientific paper: “An ammonite trapped in Burmese amber” by Tingting Yu, Richard Kelly, Lin Mu, Andrew Ross, Jim Kennedy, Pierre Broly, Fangyuan Xia, Haichun Zhang, Bo Wang, and David Dilcher published in the “Proceedings of the National Academy of Sciences of the United States of America.

22 05, 2019

Fossilised Mouse Reveals Evolutionary Secrets of Colour

By | May 22nd, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

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 a prehistoric mouse.

The Fossilised Remains of a Prehistoric Mouse

The fossilised remains of a mouse.

The well-preserved remains of a Pliocene mouse used in the study.

Picture Credit: The University of Manchester

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

Apodemus atavus - mouse from the Pliocene helps reveal the evolution of pigmentation.

A life reconstruction of the mouse from the Pliocene – Apodemus atavus.

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 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

A false colour image of the fossil mouse.

A false colour image of the 3 million-year-old fossil mouse used in the red pigment study.

Picture Credit: The University of Manchester

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.

17 05, 2019

The Jurassic Angiosperm Gap

By | May 17th, 2019|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles|0 Comments

The Jurassic Angiosperm Gap

Today, the flora of the world is dominated by the angiosperms (flowering plants), they are the most diverse and widespread group of land plants comprising more than four hundred families, but their origin remains a mystery.  The fossil record for flowering plants is sparse, but there are numerous, unequivocal angiosperm fossils known from Cretaceous rocks.  Fossils of angiosperms from the Cretaceous appear abruptly and demonstrate a remarkable abundance of different forms.  The apparently rapid evolution of flowering plants in the Cretaceous was commented upon by Charles Darwin, the author of the ground-breaking “The Origin of Species”.  Darwin described the diverse Cretaceous-aged fossils of flowering plants when very few earlier flowering plant fossils were known as “a great abominable mystery.”

To read an earlier article (published in 2018), that looked at the puzzle of when angiosperms evolved: When Did Flowers First Evolve?

Fossils of Water Lilies (Nymphaeales) Are Known from the Cretaceous but when did the Flowering Plants Evolve?

A water lily in flower.

From the time of the Dinosaurs, but when did the angiosperms first appear?

Picture Credit: Everything Dinosaur

Molecular Clock Dating and Genome Analyses Indicate Origins Earlier in the Mesozoic

Molecular clock studies have frequently suggested an earlier origin for angiosperms in the Jurassic, or even potentially within the Triassic.  However, many studies have lacked extensive sampling, especially at the ordinal and familial levels.  Now, in a new scientific paper published in the journal “Nature Plants”, researchers from the Chinese Academy of Sciences have mapped and plotted a comprehensive angiosperm phylogeny, sampling nearly 3,000 chloroplast genomes from species representing all 64 known plant Orders and 85% of all the flowering plant families described to date.  This most intensive study of living flowering plants has been cross-referenced with the fossil record of angiosperms and indicates an origin of these types of plants in the Late Triassic (around 209 million years ago – Norian stage of the Late Triassic).

This earlier age for angiosperm evolution leaves a gap between the earliest fossils and the origins of flowering plants of almost 70 million years, roughly the length of the entire Jurassic period, the authors term this huge period of geological time as “the Jurassic Gap”.

Identifying “The Jurassic Gap” in the Angiosperm Lineage

The "Jurassic Gap" in the evolutionary history of flowering plants.

Identifying the angiosperm “Jurassic gap”.  If flowering plants originated around 209 million years ago, then there is a gap of some 70 million years in the fossil record which if filled in would plot the rise of this important group and their radiation.

Picture Credit: Nature Plants with additional annotation by Everything Dinosaur

Arising in the Late Triassic and Early Jurassic

The authors of the paper propose that the earliest lineages of flowering plants originated in the Late Triassic or Early Jurassic.  These early parts of the angiosperm family tree are represented (as expected), by a few species totalling no more than a couple of hundred taxa or so.  These early members of the angiosperm group include water lilies (Nymphaeales), the woody plant order Austrobaileyales, which contains star anise and the large shrub Amborella trichopodanative to the island of New Caledonia in the southwest Pacific Ocean, a plant which is regarded as the sister taxon to the remaining angiosperms.

The data generated by the scientists indicates that major diversifications subsequently occurred in the Late Jurassic and Early Cretaceous resulting in 99.95% of the extant diversity of flowering plants.  The relationships of the five major clades of this large diversification (core angiosperms) have long been difficult to determine and the researchers conclude that despite this extensive study, more work is required to resolve this aspect of flowering plant evolution.

Linked to the Rise of Insects – Symbiotic Relationships with Flowering Plants

If the first angiosperms arose in the Triassic, this corresponds with the timing of the evolution of several types of insects including katydids, crickets, alderflies and the common ancestor of the Lepidoptera (moths and butterflies).  However, the spectacular diversification of core angiosperms in the Jurassic and Early Cretaceous notably also coincides with the origin and evolution of the Phytophaga, arguably the most diverse radiation of plant-feeding beetles.  Their association with angiosperms has long been proposed to account for the apparent evolutionary success of the Phytophaga.  Furthermore, modern beetle diversity in general as well as other pollinators, including moths and butterflies, had their origins in the Cretaceous, which coincides with the rise of flowering plants to ecological dominance and the major diversifications of extant angiosperm diversity in the phylogeny as reported by the Chinese Academy of Sciences.

The Present-day Diversity of Beetles Could be Linked in Part to the Success of Flowering Plants

A beetle.

Soldier Beetle – the evolution and radiation of flowering plants is linked to the radiation of the Insecta – a result of the symbiotic relationship between many angiosperms and insects.

Picture Credit: English-Country-Garden.com

To read an article about ancient wing scales found in a drill core that suggests a Triassic origin for the Lepidoptera: Ancient Butterflies Flutter By

Why the Jurassic Gap?

One explanation put forward for the “Jurassic Gap” is that in the early days of flowering plant evolution, these plants were rare and thus the chances of any number becoming preserved as fossils were slim.  Another explanation proposed, is perhaps they occurred in habitats that were unsuitable for preservation such as forests.  Charles Darwin commented that it was “wretchedly poor conjecture” that angiosperms could have had a pre-Cretaceous history on a remote, but lost, island, meaning that all evidence of early flowering plants had been essentially wiped out.

A somewhat less exotic explanation is that the structures, flowers or fruits of early flowering plants were too small to now be confidently assigned to angiosperm lineages.  Perhaps, more fossils will be found to help plug the “Jurassic Gap”, but for the time being this period of seventy million years or so remains a mystery.

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

14 05, 2019

Archaeopteryx Gets Company

By | May 14th, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Photos/Pictures of Fossils|0 Comments

Alcmonavis poeschli – Another Late Jurassic “Early Bird”

Scientists have identified a new species of “proto-bird” which was contemporaneous with Archaeopteryx (A. lithographica).  Known from a single, fragmentary fossil, excavated from the Lower Tithonian Mörnsheim Formation of the Solnhofen Archipelago, the species has been named Alcmonavis poeschli.  Its discovery supports the hypothesis that there were numerous bird-like dinosaurs in the Late Jurassic.

The Late Jurassic of Europe Could Have Been Home to Numerous “Proto-birds”

Archaeopteryx could have been one of numerous bird-like dinosaurs from the Solnhofen Archipelago.

Picture Credit: Carl Buell

A Right Wing from a Volant Animal

A. poeschli is represented by a right wing (specimen number: SNSB-BSPG 2017 I 133).  The bones are partially dislocated but lying in proximal association, the fossils consist of the humerus, radius, ulna, the hand and finger bones with claws.  Although there are only a handful of bones to study, they show a number of derived characters such as a pronounced attachment area for the pectoralis muscle and a robust second finger.  These traits indicate that Alcmonavis is a more derived avialan than Archaeopteryx.

A Photograph Showing the Holotype Fossil of Alcmonavis poeschli

Alcmonavis poeschli holotype fossil material.

Alcmonavis poeschli holotype.

Picture Credit: Bayerische Staatssammlung für Paläontologie und Geologie/AFP

The photograph (above), shows the wing of Alcmonavis poeschli as it was found in the limestone slab.  Alcmonavis poeschli is another example of a volant bird from the Jurassic period.  It may have been a more capable flyer than the urvogel (Archaeopteryx).  Scars on the wing bones suggest the placement of sizeable muscles, indicating that the raven-sized Alcmonavis was capable of flapping its wings with some force.

One of the authors of the scientific paper, published this week in the academic journal “eLife”, Oliver Rauhut of the Bayerische Staatssammlung für Paläontologie und Geologie (Bavarian State Collection of Palaeontology and Geology) stated:

“At first, we assumed that this was another specimen of Archaeopteryx.  There are similarities, but after detailed comparisons with Archaeopteryx and other, geologically younger birds, its fossil remains suggested that we were dealing with a somewhat more derived bird.  The wing muscles indicate a greater capacity for flying.”

This discovery indicates higher avialan diversity in the Late Jurassic than previously recognized.

Named after the Altmühl River

The genus name is derived from the old Celtic name for the Altmühl River which flows through the Solnhofen limestone region and from the Greek “avis” for bird.  The species name honours Roland Pöschl who leads fossil hunting expeditions to the Old Schöpfel Quarry, where the fossilised wing was discovered.

To read an article published in 2017 about another feathered dinosaur from Solnhofen: The Archaeopteryx That Wasn’t

To read an article from February 2019, that explains how the iconic Archaeopteryx feather fossil was reclassified: Iconic “Archaeopteryx” Feather Not From Archaeopteryx

13 05, 2019

“Oh We Do Like to be Beside the Seaside” – Triassic Marine Phytosaurs

By | May 13th, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Photos/Pictures of Fossils|0 Comments

Austrian Phytosaur Fossils Point to Phytosaurs in Marine Environments

Look at most books that feature an illustration of the fauna of the Triassic and it is likely that squeezed into the colourful but so spurious illustration of early dinosaurs, beaked rhynchosaurs and cynodonts all going about their business but effectively ignoring each other, you will spot a phytosaur.  Phytosaurs, the long-snouted, semi-aquatic carnivores that resembled crocodiles but were certainly not crocodilian, were widely distributed during the Triassic.  However, very little evidence had emerged that linked these predators with marine ecosystems.  It had been thought phytosaurs were confirmed to freshwater or brackish environments.  The publication of a new scientific paper, reporting on the discovery of the remains of at least four individuals from an ancient lagoon, represents the best evidence yet that these formidable predators also inhabited the sea.

Phytosaurs in Marine Ecosystems

Mystriosuchus steinbergeri life reconstruction.

A newly described species of Austrian phytosaur provides evidence of a marine existence.  Mystriosuchus steinbergeri life reconstruction.

Picture Credit: Mark Witton (© 2019 The Linnean Society of London, Zoological Journal of the Linnean Society)

Mystriosuchus steinbergeri

Although the fossil remains were laid down in a coastal, lagoonal environment, these days, thanks to plate tectonics, the quarry site is two kilometres above sea level in a remote part of the Austrian Alps.  The fossils were found in 1980 by Sepp Steinberger, a member of a local caving club.  The species name (Mystriosuchus steinbergeri), was erected in his honour.  One of the reasons cited for the amount of time it has taken to fully study these fossils is that despite the relative abundance of phytosaur fossils compared to other Triassic vertebrates, there are not that many vertebrate palaeontologists that specialise in studying the Phytosauria.

Phylogenetic analysis positions this newly described species as the sister taxon to a clade comprising Mystriosuchus planirostris and Mystriosuchus westphali.  A study of the fossil bones indicates that the Austrian phytosaur specimens represent individuals that were at least eight years of age at the time of their death.  The palaeoenvironmental data recovered suggests that these archosaurian reptiles were living in a marine lagoon.  This provides strong evidence to support the idea that some phytosaurs may have adapted to living in saltwater as well as freshwater environments.

A Classic Triassic Diorama Depicting a Phytosaur

A phytosaur in a Triassic diorama.

A beautifully painted Triassic scene (Rudolph Zallinger).  A newly published scientific paper provides strong evidence for marine adaptations in the Phytosauria.

Picture Credit: Rudolph Zallinger

How Did They Die?

Everything Dinosaur contacted one of the authors of the scientific paper, Richard Butler (School of Geography, Earth and Environmental Sciences, University of Birmingham), enquiring about the discovery of four individuals, all roughly the same age and the same size (approximately 4 metres in length), being found together.

Professor Butler commented:

“As to how these animals died and were buried together, your guess is as good as mine!  It’s a puzzle, and I don’t have an answer.  However, I think it’s very unlikely that they died together on land and were somehow washed out tens of kilometres and buried together.  I think it’s more likely that they were living in the lagoon and died near to where they were buried.  Interestingly, the fact that there are multiple individuals all of a similar size might suggest some social/group behaviour, although again it’s quite speculative.”

When asked to put into context the significance of this evidence supporting the idea of some members of the Phytosauria adapting to marine environments, Professor Butler explained that there have been a handful of occurrences of the species Mystriosuchus planirostris recorded in marine sediments in northern Italy, and the basal phytosaur Diandongosuchus was also found in a marine deposit.  These fossil discoveries have led to speculation that both these species were possibly marine animals.  However, they’ve all been isolated specimens, and in the northern Italian sequences, for example, there is evidence to indicate that fully terrestrial animals had been washed into these marine deposits.  So, in the case of these fossils,  it is plausible that rather than being examples of marine phytosaurs, these are terrestrial phytosaurs that died on land and were washed out to sea.  The Austrian phytosaur material ascribed to Mystriosuchus steinbergeri might not be the first evidence found to support a marine environment hypothesis but it does probably represent the strongest evidence found to date.

The professor concluded that if he and his fellow authors are correct, then the phytosaurs represent yet another group of tetrapods that independently invaded marine environments.

The scientific paper: “Description and Phylogenetic Placement of a New Marine Species of Phytosaur (Archosauriformes: Phytosauria) from the Late Triassic of Austria” by Richard J Butler, Andrew S Jones, Eric Buffetaut, Gerhard W Mandl, Torsten M Scheyer and Ortwin Schultz published in the Zoological Journal of the Linnean Society.

8 05, 2019

A New Jurassic Scansoriopterygid Dinosaur – Ambopteryx

By | May 8th, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Ambopteryx longibrachium – A New Bat-winged Dinosaur

Scientists from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), have identified a new species of flying dinosaur from Jurassic-aged strata in north-eastern China.  This dinosaur has been identified as a member of the Scansoriopterygidae dinosaur family and it had bat-like, membranous wings just like the related Yi qi, that was named and described back in 2015.  The little dinosaur, not much bigger than a starling, had a flap of skin from its arms to its torso, in essence a wing.  It has been named Ambopteryx longibrachium and this discovery supports the idea that within the forests of northern China during the Middle to the Late Jurassic, dinosaurs were experimenting with several different methods of gliding and powered flight.

A Life Reconstruction of the Newly Described Scansoriopterygid Dinosaur Ambopteryx longibrachium

Ambopteryx longibrachium life reconstruction.

A life illustration of Ambopteryx longibrachium.

Picture Credit: IVPP (Chinese Academy of Sciences)

Bizarre and Buck-toothed Little Flying Dinosaur

The fossil specimen was found by a local farmer who supplements his income like many folk in Liaoning Province by searching for fossils in the fine-grained sediments.  It is beautifully preserved and dates to around 163 million years ago, commenting on the discovery, one of the co-authors of the scientific paper, published this week in the journal “Nature”, Jingmai O’Connor of the IVPP stated:

“It would have been this tiny, bizarre-looking, buck-toothed thing like nothing alive today.”

The Beautifully Preserved Fossil Specimen (Ambopteryx longibrachium)

Ambopteryx fossil specimen.

Ambopteryx longibrachium fossil.

Picture Credit: Min Wang IVPP (Chinese Academy of Sciences)

A Secondary Form of Flight That Does Not Involve Feathers

Close to the origins of flight, dinosaurs closely related to birds were experimenting with a range of different wing structures.  One of the most bizarre of these is the scansoriopterygid named Yi qi, (pronounced: Ee-chee), which was described and named in 2015.  This little dinosaur had membranous wings, supported by a curved, rod-like bone (styliform), attached to the wrist.  Soft tissue proximal to the arm bones was interpreted as bat-like wings, although this interpretation was not widely accepted by the scientific community.  However, the discovery of another type of scansoriopterygid dinosaur with the same type of wings demonstrates that members of the Scansoriopterygidae were indeed taking to the air.

The new dinosaur, Ambopteryx longibrachium (meaning “both-wing” and “long arm,” a reference to this second method of dinosaur flight, one that does not involve feathered wings), provides confirmatory evidence of the evolution of dinosaurs with bat-like, membranous wings.

Palaeontologist Steve Brusatte, (University of Edinburgh), when asked to reflect on the significance of this newly published scientific paper commented:

“This fossil seals the deal, there really were bat-winged dinosaurs.”

Ambopteryx longibrachium – Takes to the Air

A gliding Ambopteryx longibrachium (dorsal view).

Ambopteryx longibrachium (dorsal view).  The speculated flying pose of this new Chinese dinosaur.

Picture Credit: Min Wang IVPP (Chinese Academy of Sciences)

An Evolutionary Dead End

The researchers conclude that marked changes in wing design evolved near the split between the Scansoriopterygidae and the avian lineage, the two clades took very different routes to becoming volant.  Furthermore, the scientists determine that the membranous wings supported by elongate forelimbs present in scansoriopterygids such as Yi and Ambopteryx was a short-lived evolutionary experiment and that the feathered, winged dinosaurs ultimately proved to be the more successful leading to the eventual evolution of the Aves.  The likes of Yi qi and Ambopteryx longibrachium were evolutionary dead ends.  Whether Ambopteryx was capable of sustained powered flight, or whether it moved from tree to tree entirely by passive gliding remains unknown.

Coming in to Land – Ambopteryx longibrachium

At home amongst the trees Ambopteryx longibrachium.

Coming into land, a gliding Ambopteryx moving effortlessly from tree to tree.

Video Image Credit: Min Wang IVPP (Chinese Academy of Sciences)

Stomach Contents Preserved

The stomach contents of the little dinosaur have been preserved.  The Chinese scientists recovered pieces of bone and small stones (gastroliths), which modern birds use to grind plant material, indicating Ambopteryx may have been omnivorous.  It may have lacked pinnate feathers, but the body was covered by a downy fuzz to help this small dinosaur keep warm.  Jingmai O’Connor speculates that male Ambopteryx may have sported long, ornamental tail feathers, as seen in other scansoriopterygids such as Epidexipteryx (E. hui).

The scientific paper examines the anatomical traits that enabled a mode of flight.  The wings of Ambopteryx were formed by elongated arm bones (humerus and ulna).  Aves (birds), have elongated finger bones (metacarpals), in effect, different solutions found in nature to achieve the same aim – volant activity.

Professor O’Connor added:

“The main lift-generating surface of bird’s wings is formed by the feathers.  In bats, pterosaurs and now scansoriopterygids, you have instead flaps of skin that are stretched out in between skeletal elements.”

Yi qi was Not Alone

It seems likely therefore, that with the discovery of a second bat-winged scansoriopterygid, there may be numerous other fossils of bizarre dinosaurs that were adapted to a life in the trees awaiting discovery in Liaoning Province.  It now seems that flight evolved more than once in the Dinosauria, Yi qi was not alone and the scientific community will provide further insight in the near future with regards to the remarkable and arguably the strangest of all the dinosaurs the Scansoriopterygidae.  Such research might be hindered by the small body-size of these creatures, the Ambopteryx specimen represents a sub-adult animal, it would have measured in life around 32 cm in length and weighed just a few hundred grammes.  Epidexipteryx and Yi qi were also small, E. hui has been estimated to have measured 30 cm long and weighed less than 200 grammes, whilst Yi qi is estimated to have had a wingspan of less than 60 cm and it would have been not much heavier.  The fact that any specimens of these tiny arboreal dinosaurs have survived at all is remarkable in itself.

A spokesperson from Everything Dinosaur commented:

“Much of our knowledge about these tree-dwelling dinosaurs has been derived from fossils discovered in the last twelve years or so.  Our blog was started back in 2007 and over the course of the life of our blog we have charted the rise in the knowledge and awareness surrounding the curious Scansoriopterygidae.  There has even been a model of scansoriopterygid produced by a mainstream manufacturer.  PNSO introduced a model of Yi qi this year.  Who knows what other remarkable dinosaurs are awaiting discovery?”

The PNSO Yi qi Dinosaur Model

Yi qi dinosaur model (PNSO).

PNSO Yi qi dinosaur model.

Picture Credit: Everything Dinosaur

To read about the discovery of Epidexipteryx: Is it a Bird? Is it a Plane? No, it’s Epidexipteryx!

To read about the discovery of Yi qiYi qi The Dinosaur that Thought it was a Bat

To view the Yi qi dinosaur model and the other figures in the PNSO model range: PNSO Age of Dinosaurs

6 05, 2019

Suskityrannus – Our Best Glimpse Yet of a Mid-Cretaceous Tyrannosauroid

By | May 6th, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Suskityrannus hazelae – The Shape of Things To Come

The first of what will probably turn out to be numerous new Theropod dinosaurs from southern Laramidia has been announced today.  Writing in the academic journal “Nature: Ecology & Evolution”, a team of international scientists have described a new species of relatively small-bodied tyrannosauroid that helps to fill a gap in the evolution of the Tyrannosaur family.  Significantly, the new dinosaur, named Suskityrannus hazelae, has the same general body shape and feet adapted to running (arctometatarsalian feet), as the later, much larger Tyrannosaurs such as Albertosaurus, Gorgosaurus and T. rex.  This suggests that Tyrannosaurs evolved many of their characteristic features whilst they were relatively small, secondary predators.   When Suskityrannus roamed western North America some 92 million years ago (Middle Turonian faunal stage), this little Theropod was the shape of things to come.

A Life Reconstruction of Suskityrannus hazelae

Suskityrannus hazelae life reconstruction.

The newly described Suskityrannus walks past two unconcerned Zuniceratops.

Picture Credit: Andrey Atuchin

The Moreno Hill Dinosaur Assemblage

Suskityrannus heralds from the Zuni Basin of New Mexico, specifically the Moreno Hill Formation and it has been described based on two associated but fragmentary skeletons.  Even so, these fossils represent the most complete examples of early Late Cretaceous tryannosauroids described to date.  Dinosaur fossils from the Turonian faunal stage are exceptionally rare, the fossils from the Moreno Hill Formation have provided palaeontologists with an insight into the types of dinosaur that were the forerunners of the key groups of dinosaur that were to dominate the terrestrial ecosystems of North America towards the end of the Cretaceous.  For example, the beautiful life reconstruction of Suskityrannus by Andrey Atuchin (above),  shows a three-metre long Theropod about to feed on some garfish that have become stranded as a result of a flood.  The pair of Zuniceratops are unconcerned about the proximity of the meat-eater, they are many times heavier and have nothing to fear from the fleet-footed tyrannosauroid.  In the background, to the right of the image a large Ornithopod dinosaur can be seen, we think this is probably a life reconstruction of the basal hadrosauroid Jeyawati.

In essence, that is what makes the dinosaurs from the Moreno Hill Formation so significant.  These sediments were laid down before the diversification of the tyrannosaurids, hardrosaurids and ceratopsids, all key components in later Cretaceous dinosaur assemblages from North America.

A Powerful Bite

Named Suskityrannus hazelae, (pronounced Sus-key-tie-ran-us haze-ah-lie), analysis of the jaw bone indicates that this dinosaur had an elongated skull measuring between 25 and 32 cm in length.  Despite its small size, less than 3 metres long, with a hip height of around 1 metre, Suskityrannus had a powerful bite, foretelling the evolutionary direction of later Tyrannosaurs which were to evolve massive skulls with bone crushing bite forces.

The Fossil Skeleton of S. hazelae Compared to the Dentary (Lower Jaw) of Tyrannosaurus rex

Suskityrannus compared to the jaw bone of a T. rex.

The fossil remains of Suskityrannus compared to a lower jaw from a Tyrannosaurus rex.

Picture Credit: Virginia Tech

What’s in a Name?

The name Suskityrannus hazelae is derived from “Suski,” the Zuni Native American tribe word for “coyote,” reflecting this tyrannosauroid’s position in the ecosystem as a secondary predator.  The species name honours Hazel Wolfe whose support made possible many expeditions to the Zuni Basin of New Mexico.  The first evidence, including a partial skull was found in 1997 by co-author Robert Denton (GeoConcepts Engineering).  The second, more complete specimen was found in 1998 by Sterling Nesbitt, a high school student at the time, but now based at the Department of GeoSciences (Virginia Tech).  Dr Nesbitt is the corresponding author for the scientific paper.  The fossils were housed at the Arizona Museum of Natural History for many years before they were formally studied.

Co-author, Steve Brusatte (School of GeoSciences, University of Edinburgh) commented:

“Suskityrannus is a key link between the enormous bone-crunching dinosaurs like T. rex and the smaller species they evolved from.  The new species shows that Tyrannosaurs developed many of their signature features like a muscular skull, broad mouth, and a shock-absorbing foot when they were still small, maybe as adaptations for living in the shadows.”

Dr Sterling Nesbitt and Suskityrannus hazelae

Co-author Sterling Nesbitt and fossil remains of Suskityrannus.

Corresponding author Sterling Nesbitt, with the fossilised remains of Suskityrannus laid out in their anatomical position.

Picture Credit: Virginia Tech

The Moreno Hill and the Bissekty Formations

The Moreno Hill Formation is analogous to the Bissekty Formation of Uzbekistan.  Within the northern hemisphere, dinosaur fossils from the Turonian faunal stage are exceptionally rare, although thousands of miles apart, the strata are approximately the same age (around 90 million-years-old) and the dinosaur specimens found provide evidence of similar faunas.  The tyrannosauroid Timurlengia was named and described from fragmentary remains from the Bissekty Formation in 2016, the publication of a scientific paper on Suskityrannus will help palaeontologists to better understand how relatively small-bodied tyrannosauroids evolved into giant apex predators some twenty million years later.

To read about the discover of Timurlengia: Fossil Study Suggests How Tyrannosaurs Got Big

How Big Were the Arms of Suskityrannus?

As for that other famous Late Cretaceous Tyrannosaur body trait, the much reduced arms, scientists are very much in the dark about how big the forelimbs of Suskityrannus were.  Very little forelimb fossil material has been recovered.  Scientists can’t even say with any certainty whether Suskityrannus had two-fingered or three-fingered hands.  Cross-sectional analysis of slices of bone indicate that both known specimens were juveniles.  The fossils are providing further information on tyrannosauroid ontogeny.  Despite not being fully-grown, the authors are confident that Suskityrannus was not as big as its descendants, the famous apex predators of the Campanian and Maastrichtian faunal stages of the Cretaceous.

Commenting on the discovery a spokesperson from Everything Dinosaur stated:

“When we made our palaeontology predictions for 2019, the last prediction we made was that more tyrannosaurids would be named and described from fossil material associated with southern Laramidia.  We suggested that two new species would be named.   Suskityrannus hazelae has helped us to confirm our prediction made earlier this year, at least in part.  We are expecting more Theropod news to come out of the southern United States over the next few months.  These are exciting times for anyone studying the Tyrannosauroidea.”

To read about the discovery of a tyrannosauroid from central Utah that lived approximately four million years before Suskityrannus: Moros intrepidus Fleet Footed Tyrannosauroid Leaps 70 Million Year Gap

4 05, 2019

How Dinosaurs Ran Could Provide Key to Origins of Flight

By | May 4th, 2019|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page|0 Comments

Caudipteryx Flapped its “Wings” as it Ran

Scientists from Tsinghua University (Beijing), in collaboration with colleagues from the Chinese Academy of Sciences have suggested that the way in which some Theropod dinosaurs ran caused their feathered arms to move up and down.  Involuntary wing flapping might have been the first stage in the evolution of powered, active flight.  This is the conclusion reached in a new scientific paper published in the academic journal “PLOS – Computational Biology”, after a series of highly innovative experiments that involved building a robotic dinosaur and strapping artificial wings to young ostriches.

Modelling the Running Action of Caudipteryx

Calculating the flapping of the wings (Caudipteryx).

Mechanically modelling the running action of the basal feathered dinosaur Caudipteryx.

Picture Credit: PLOS – Computational Biology

Ground Up or Tree Down

Most scientists now accept that the Dinosauria is divided into two divisions, the avian dinosaurs – the birds and the non-avian dinosaurs, essentially all the other dinosaurs.  In addition, it is also widely believed that a type of maniraptoran dinosaur (a clade that contains true birds and those dinosaurs closely related to birds), evolved into our feathered friends.  Trouble is, how did powered flight, a trait very closely associated with most birds alive today come about?  Were some dinosaurs arboreal, clambering amongst the branches of trees and they then evolved the ability to glide and finally powered flight came about in what is described as a “tree down” approach.  Or, were fast-running, cursorial dinosaurs learning to leap into the air and over many generations, feathered arms became longer and stronger and the lift generated led to the evolution of volant dinosaurs and subsequently the birds?  This theory is termed “ground up”.

The debate has persisted for more than a hundred years.

Proavis – A Hypothetical Attempt to Assess “Ground Up” – Fast Running Led to the Evolution of Powered Flight

A model of the hypothetical transitional animal Proavis.

A model of the hypothetical animal Proavis.  An early attempt to examine how fast-running bipedal animals might have evolved into birds.

Picture Credit: Grant Museum of Zoology

Taking a Mechanical Approach

The researchers adopted a mechanical approach to this evolutionary conundrum.  They looked at one of the most basal, non-flying feathered dinosaurs known – Caudipteryx and assessed whether if this dinosaur ran fast enough, its running gait might have caused its feathered arms to flap involuntarily.  In theory, if the arms were strong enough, the wings and their feathers large enough, flapping whilst running fast could generate lift and if the lift to body weight ratios were right, then the dinosaur could take to the air.  In essence, passive wing flapping may have been an evolutionary precursor to later active wing flapping and powered flight.

An Illustration of Caudipteryx

Cauditperyx.

A basal feathered dinosaur that could not fly, but could it flap?

Picture Credit: Everything Dinosaur

An assessment of the fossilised bones of the pheasant-sized Caudipteryx led the researchers to determine that Caudipteryx had a top speed of 8 metres per second (28.8 kmh or 18 mph).  However, simulations using mechanical and computer models suggested that at even lower speeds from 2.5 to 5.8 metres per second, the gait of Caudipteryx would have created strong enough vibrations through its body to cause the wings to flap.

Testing the Physical Movement of Artificial Wings on Young Ostriches

Young ostriches fitted with artificial wings.

Testing the movement of artificial wings in young ostrich locomotion study.

Picture Credit: PLOS – Computational Biology

A Life-size Robotic Caudipteryx

To test their calculations, the scientists built a life-size, robotic Caudipteryx and tested its running performance on a treadmill.  Several young ostriches were kitted out with artificial wings equipped with sensors that could detect lift and forward thrust, or any coefficient drag.  These birds were then put on the treadmill to see how they would perform.  In addition, five different sizes of feathers on the wings were tried, the larger feathers producing more results akin to the development of powered flight.

Five Different Wing Sizes and Feathers were Tested

Wing and feather variations used in the locomotion experiment.

Five different wing and feather combinations were tested.

Picture Credit: PLOS – Computational Biology

Professor John Hutchinson (Royal Veterinary College, London), an expert on animal locomotion, although not directly involved in the research, described this physical modelling approach as “ambitious and creative”, but questioned the paper’s main findings.  The study, for example, may have oversimplified the biology, reducing a living organism to a series of springs and constituent parts with individual mass, subsequently compiled to produce a single result.  Caudipteryx could have ran with its arms held very close to its body, helping it to reduce air resistance as it moved quickly, but also negating some of the lift and thrust that might have been generated by its feathered forelimbs.

Despite his reservations, Professor Hutchinson sees this study has helping to “lay groundwork that could be built upon and tested more rigorously.”

It seems that for the time being, the debate between “tree down” and “ground up” remains unresolved and it is not certain how much of a role passive arm flapping as a result of terrestrial locomotion influenced the evolution of active wing flapping, the precursor to a truly aerial existence.

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