Middle Jurassic Dinosaur Tracks Put Skye Firmly on the Map

More evidence of Middle Jurassic dinosaurs on the Isle of Skye has emerged.  In a paper published in the Scottish Journal of Geology, a team of international scientists including researchers from the University of Edinburgh and the Chinese Academy of Sciences, report on a series of dinosaur prints and tracks from the Lealt Shale Formation (Bathonian faunal stage) of the Great Estuarine Group at Rubha nam Brathairean (Brothers’ Point), on the Trotternish peninsula (Isle of Skye).

Middle Jurassic Dinosaurs

Evidence of Middle Jurassic dinosaurs is globally rare, there are just a few fossil sites that provide information about terrestrial fauna that existed around 168 million years ago.  Trace fossils from the Isle of Skye are playing an increasingly significant role as palaeontologists seek to better understand the evolution and distribution of different types of dinosaur.

One of the Sauropod Prints at Rubha nam Brathairean

Picture credit: Jon Hoad

In 2015, Everything Dinosaur published an article featuring the discovery of a series of sauropod prints and tracks found on northern Skye, at a locality close to Duntulm Castle (Duntulm Formation).

To read this article: Isle of Skye Sauropods and their Water World.

Although, the Duntulm Castle site is just a few miles from the newly described trace fossils at Brothers’ Point and the strata in which the footprints and tracks were found are part of the Great Estuarine Group sequence of Middle Jurassic rocks, the two fossil sites represent different sub-units of strata.  The Lealt Shale Formation is geologically older than the fossiliferous rocks found at the Duntulm Castle site (Duntulm Formation).

Brackish, Lagoonal Environments Occupied by Middle Jurassic Dinosaurs

Both locations represent a sequence of deposits made in brackish, lagoonal environments.  The fact that a second series of sauropod tracks and prints have been found preserved in rocks laid down in a lagoon, strengthens the idea that Middle Jurassic sauropods habitually spent time in these environments.  Could this indicate that at least some Middle Jurassic sauropods were semi aquatic?

Did Middle Jurassic Sauropods Habitually Hang Out in Lagoons?

Picture credit: Jon Hoad

Around Fifty Footprints Measured and Studied

The researchers measured, photographed and analysed around fifty footprints in a tidal area.  Working conditions on the rugged headland were difficult, due to the tidal environment and the often, inclement weather for which, the Trotternish peninsula is famed.  Despite the harsh conditions, the scientists were able to identify two trackways and many examples of isolated prints.

The location preserves numerous small sauropod manus (hand) and pes (foot) prints along with several isolated and broken medium-to-large tridactyl prints.  The three-toed (tridactyl) prints indicate the presence of theropods (most probably carnivorous dinosaurs).  Measurements of the sauropod tracks and stride lengths indicate that these trace fossils were made by relatively small members of the Sauropoda, the tracks indicate individuals around two metres high at the shoulders.

The sauropod tracks, with their characteristic narrow gauge and toe morphology, have been tentatively assigned to the ichnotaxon Breviparopus.  The theropod trackmaker remains equally enigmatic, however, some of the three-toed prints are reminiscent of the tracks associated with the ichnotaxon Eubrontes.

One of the Sauropod prints from the Lealt Shale Formation

Picture credit: Paige dePolo (University of Edinburgh)

Commenting on the Discovery

Commenting on the significance of this discovery, one of the authors of the scientific paper, Paige E. dePolo (University of Edinburgh) stated:

“This tracksite is the second discovery of sauropod footprints on Skye.  It was found in rocks that were slightly older than those previously found at Duntulm on the island and demonstrates the presence of sauropods in this part of the world through a longer timescale than previously known.  This site is a useful building block for us to continue fleshing out a picture of what dinosaurs were like on Skye in the Middle Jurassic.”

Co-author Dr Stephen Brusatte (University of Edinburgh), added:

“The more we look on the Isle of Skye, the more dinosaur footprints we find.  This new site records two different types of dinosaurs — long-necked cousins of Brontosaurus and sharp-toothed cousins of T. rex — hanging around a shallow lagoon, back when Scotland was much warmer and dinosaurs were beginning their march to global dominance.”

A Fossil Bias?

Although the discovery of a second site, demonstrating sauropod tracks in a lagoonal depositional environment, raises the intriguing idea that these large, long-necked herbivores spent time in such environments, palaeontologists have to be careful what they infer from such data.  Sauropods may have spent much of their time in different habitats, such as forests, or perhaps, in more open environments such as fern prairies, however, in such environments the fossil preservation potential for things like tracks and footprints are that much lower.  Hence, the evidence for such behaviour may not exist, there could be a preservational bias in favour of recording sauropod activity in brackish lagoons.

Thanks to this dedicated research team, more information has been obtained with regards to the Middle Jurassic palaeofauna of Scotland.  We look forward to future discoveries and fossil finds that will continue to inform the debate.

For models and replicas of sauropods and other dinosaurs: Wild Safari Ltd Prehistoric World Dinosaurs.

The scientific paper: “A Sauropod-dominated Tracksite from Rubha nam Brathairean (Brothers’ Point), Isle of Skye, Scotland” by Paige E. dePolo, Stephen L. Brusatte, Thomas J. Challands, Davide Foffa, Dugald A. Ross, Mark Wilkinson and Hong-yu Yi published in the Scottish Journal of Geology

“The Rise and Fall of the Dinosaurs” by Dr Steve Brusatte

One of the authors of this scientific paper (indeed one of the authors of the 2015, Duntulm Formation tracks research), Dr Steve Brusatte (School of Geosciences at Edinburgh University), has a new dinosaur book out next month.  Look out for the excellent “The Rise and Fall of the Dinosaurs” coming into shops in May.

New Dinosaur Book Out Very Soon

Picture credit: Pan Macmillan

To read Everything Dinosaur’s recent book review: A Review of “The Rise and Fall of the Dinosaurs”.

Visit the Everything Dinosaur website: Everything Dinosaur.

Updating Arkansaurus fridayi

A few days ago, Everything Dinosaur published an article about the newly described basal ornithomimosaur called Arkansaurus fridayi.  Although the fossil bones were found nearly fifty years ago, the scientific paper describing the fossils and officially naming this dinosaur has only just been published (Journal of Vertebrate Palaeontology).  Lead author of the paper, ReBecca Hunt-Foster of the Bureau of Land Management, emailed us so that we could post up more images of this significant fossil discovery.

A Life Restoration of the Basal Ornithomimosaur Arkansaurus fridayi

Picture credit: Brian Engh

To read Everything Dinosaur’s earlier article on the formal description of Arkansaurus: “Arkansas Reptile” – A Rare Insight into Appalachian Dinosaurs.

More Primitive Than Asian Ornithomimosaurs That Lived at the Same Time

Ornithomimosaurs (the ostrich-mimic dinosaurs) are quite well known from the Early Cretaceous of Asia, however, very little is known about North American ornithomimosaurs from this time in Earth’s history, hence the importance of the Arkansaurus fossils.  The dinosaur has been named from a single, partial right foot, recovered from the Lower Cretaceous (Albian to Aptian faunal stages) of the Trinity Group of Arkansas.

A Cast of the Fossil Foot Bones (Anterior View)

Picture credit: R. Hunt-Foster

Studying Arkansaurus fridayi

Contemporaneous with the likes of Beishanlong (B. grandis) from Gansu Province (north-west China), living around 113 million years ago, Arkansaurus fridayi can be distinguished from other ornithomimosaurs based on differences in the toe claws (pedal unguals) and the presence of a laterally compressed third metatarsal (toe bone) that is ovoid in shape when looked at in proximal view.  Other anatomical differences are cited by the researchers including a distal ungual with a very weak flexor tubercle, lacking spurs.

Two Views of the Metatarsal Bones of Arkansaurus

Picture credit: R. Hunt-Foster

The picture above shows two views of the toe bones (metatarsals)  of Arkansaurus (a) in proximal view, that is viewed from the top of the bone closest to the ankle looking down onto the bones and (b) anterior view, viewed from the front.  The third metatarsal is actually the bone in the middle.  The scientists conclude that the condition of the third toe bone suggests that Arkansaurus fridayi is more basal than Asian ornithomimosaurs of similar age, but consistent with older North American forms.

A Cast of the Fossil Toe and Claw Bones

Picture credit: R. Hunt-Foster

The Radiation of the Ornithomimosaurs

This specimen provides knowledge of a poorly understood radiation of ornithomimosaurs in the Cretaceous landmass known as Appalachia and is the only known saurischian dinosaur fossil found to date in the state of Arkansas.

ReBecca Hunt-Foster Has Worked on These Fossils for Several Years

Picture credit: R. Hunt-Foster

Our thanks to Rebecca Hunt-Foster for her assistance with this article.

Visit the Everything Dinosaur website: Everything Dinosaur.

After the Carcharodontosaurids Tratayenia rosalesi Ruled

Scientists have described a new type of megaraptoran theropod dinosaur from Upper Cretaceous strata in north-western Patagonia (Argentina).  Although, less than five percent of the skeleton has been discovered, the fossil bones are similar to other megaraptorids such as Aerosteon (A. riocoloradense) and Megaraptor (M. namunhuaiquii).  This has enabled the researchers, that include Juan Porfiri from the Museo de Ciencias Naturales (Buenos Aires), and Matthew Lamanna of the Carnegie Museum of Natural History (Pittsburgh), to confidently assign these fossils to the Megaraptora clade, the clade of “giant thieves”!

A Scientific Illustration of the New South American Megaraptoran T. rosalesi

Picture credit: Andrew McAfee (Carnegie Museum of Natural History)

Tratayenia rosalesi

Described from a series of articulated dorsal and sacral vertebrae, along with two ribs and elements of the hips, the dinosaur named Tratayenia rosalesi is estimated to have been around eight to nine metres in length, possibly even bigger.  Tratayenia is the geologically youngest of the Megaraptora known to science and it is the first megaraptoran that preserves the complete sequence of sacral vertebrae (fused back bones located over the hips).

Its discovery has helped palaeontologists to learn more about the hips and pelvic region of these Late Cretaceous meat-eaters.  The genus name is from Tratayén, the area in the eastern part of Neuquén Province from where the fossils come from.  The trivial name honours Diego Rosales who made the initial fossil discovery.  Tratayenia rosalesi is pronounced tra-ta-yen-nee-ah rose-ah-less-eye.

View of the Articulated Dorsal and Sacral Vertebrae (Tratayenia rosalesi)

Picture credit: Cretaceous Research

Santonian Faunal Stage

The fossil material comes from a horizon of Upper Cretaceous-aged deposits (Santonian faunal stage), in the Bajo de la Carpa Formation of the Neuquén Group (Neuquén Basin), exposed close to the small town of Añelo.  Notwithstanding the fact that the age of the fossil material representing the megaraptorids Aerosteon and Orkoraptor (O. burkei) remains uncertain, these fossils could describe the geologically youngest megaraptoran to date, thus extending their temporal range.  In addition, it is the largest carnivorous vertebrate to have been found in the Bajo de la Carpa Formation, as such, the researchers speculate that this fearsome, long-jawed, long-clawed dinosaur was an apex predator.

Based on comparisons with close relatives like Megaraptor, palaeontologists estimate that this carnivorous dinosaur sported two, forty-centimetre-long talons on the innermost fingers of each hand.  The discovery of Tratayenia adds weight to the hypothesis that the megaraptorids became the top predators in the southern parts of Gondwana following the extinction of the carcharodontosaurids.

An Illustration of Tratayenia rosalesi Showing Known Fossil Material

Picture credit: Cretaceous Research

Megaraptoran Dinosaurs

An article that explains more about the megaraptoran dinosaurs including Murusraptor: Getting Our Claws into the Megaraptora.

For an article that outlines the potential origins of the Megaraptora: “Lightning Claw” – A Deadly Predator.

The scientific paper: “A New Megaraptoran Theropod Dinosaur from the Upper Cretaceous Bajo de la Carpa Formation of North-western Patagonia” by Juan D. Porfiri, Rubén D.Juárez Valieri, Domenica D.D.Santos and Matthew C. Lamanna published in the journal “Cretaceous Research”.

Visit the award-winning Everything Dinosaur website: Everything Dinosaur.

Getting to Grips with Six New Species of Pterosaurs

The Pterosauria, that Order of winged reptiles that thrived alongside the dinosaurs were thought to have had their heyday in the Early Cretaceous. Only a single family, the Azhdarchidae (several of whom were giants), was known from the very end of the Cretaceous (Maastrichtian faunal stage).  Many palaeontologists had thought that these flying reptiles, the first vertebrates to evolve powered flight, had gone into gradual decline, slowly but surely displaced by those rapidly evolving new masters of the air, the birds.

The Diversity of the Pterosaurs in the Late Cretaceous

However, a scientific paper, published this week in the academic journal “PLOS Biology”, challenges this view.  A total of six new species, representing three families of pterosaurs have been discovered in Late Cretaceous (Maastrichtian) rocks in Morocco.  This new discovery, the most diverse Late Cretaceous pterosaur fossil assemblage found to date, suggests that the Pterosauria may not have gradually faded away, as previously thought.  Their long lineage probably ended abruptly, in essence, the Pterosauria met the same fate at the end of the Cretaceous as their archosaur cousins the Dinosauria.

A Diverse Assemblage of Pterosaurs – Late Cretaceous Morocco

Picture credit: John Conway

A Treasure Trove of Ancient Vertebrate Fossils

Writing in the journal PLOS Biology, the researchers from the University of Bath, Portsmouth University and the University of Texas at Austin, identified a total of seven species of flying reptile from fragmentary and largely isolated fossils found in marine rocks from phosphate mines in northern Morocco (Ouled Abdoun Basin).  Working in conjunction with local fossil hunters, the scientists were able to build up a collection of around two hundred pterosaur bones.

Over the years, commercial mining has revealed large numbers of marine vertebrates dating from the end of the Cretaceous and into the Palaeogene.  Cretaceous fauna associated with these deposits include turtles, plesiosaurs, mosasaurs, sharks and lots of different types of teleost (bony fish).  Occasionally the remains of terrestrial animals are preserved in such deposits, including the bones of Late Cretaceous dinosaurs, representing some of the youngest dinosaur fossils found.

To read our 2017 article about the discovery of an abelisaurid dinosaur: The Last Dinosaur in Africa.

Some of the Last Pterosaurs

The pterosaurs identified by the researchers range in size with the smallest found having a wingspan equivalent to that of an extant Golden Eagle (Aquila chrysaetos), to giants with wingspans approaching ten metres, three times bigger than the wingspan of the largest volant birds alive today.  The fossil material has been dated to just over 66 million years ago, making these pterosaurs amongst the very last of their kind on Earth.

The Mandible of the Newly Described Nyctosaurid Alcione elainus

Picture credit: PLOS Biology

Key

dgr = dorsal groove, ocl = occlusal ridge,  sym = symphysis.

Lead author of the study, Dr Nicholas Longrich, (Milner Centre for Evolution and the Department of Biology and Biochemistry, Bath University) stated:

“To be able to grow so large and still be able to fly, pterosaurs evolved incredibly lightweight skeletons, with the bones reduced to thin-walled, hollow tubes like the frame of a carbon-fibre racing bike.  Unfortunately, that means these bones are fragile and so almost none survive as fossils.”

Six New Species of Pterosaur

The researchers were able to identify six new species of pterosaur, representing three different families:

1. Tethydraco regalis (Pteranodontidae) – the youngest member of the Pteranodontidae family described to date.  Estimated wingspan around 5 metres.
2. Alcione elainus (Nyctosauridae) – wingspan estimated at about 2 metres.
3. Simurghia robusta (Nyctosauridae) – a large pterosaur with a wingspan of around 4 metres.
4. Barbaridactylus grandis (Nyctosauridae) – an even bigger pterosaur with a wingspan estimated to be about 5.2 metres.
5. Quetzalcoatlus spp. (Azhdarchidae) – described from a single neck bone (cervical vertebra) which resembles the cervical vertebrae of Quetzalcoatlus (Q. northropi).  Size estimates for this flying reptile are very speculative, however, it could have had a wingspan of around 4 metres based on comparisons with better known azhdarchid pterosaurs.
6. Sidi Chennane specimen (Azhdarchidae) – not scientifically named as yet, known from a single, partial ulna (arm bone), measuring 362 mm long, but when complete it would have been around 600 to 700 mm in length.  This suggests a giant azhdarchid pterosaur with a wingspan of approximately 9 metres.  This specimen has been named after the phosphate mine where it was found, formal scientific description will depend on the discovery of more fossil material.  The researchers conclude that this animal was probably related to the giant azhdarchid Arambourgiania philadelphiae, which is known from the Late Cretaceous of Jordan and the United States.

Late Cretaceous Pterosaur Faunas (Marine and Terrestrial) Compared to Late Cretaceous Birds

Picture credit: PLOS Biology with additional annotation by Everything Dinosaur

The diagram above compares the size disparity between Late Cretaceous pterosaurs with those of contemporaneous birds (coeval Aves – birds that lived at the same time as these flying reptiles).  Pterosaurs shaded blue are associated with marine environments, pterosaurs shaded in brown are associated with terrestrial habitats.  The six new species from the Ouled Abdoun Basin identified in the scientific paper have been given a red star.  The one species from the Ouled Abdoun Basin that had been previously described (2003), has been labelled with a green star (the azhdarchid Phosphatodraco mauritanicus).

A Giant Pterosaur

The giant pterosaur referred to as the Sidi Chennane specimen is estimated to have approached Quetzalcoatlus in size, but it was much more lightly built and therefore, presumably weighed less.  These proportions indicate a distinct flight mode and ecological niche, suggesting that giant pterosaurs occupied a range of niches in Late Cretaceous habitats.  In addition, the researchers conclude that this flying reptile fossil assemblage demonstrates that the Maastrichtian pterosaurs show increased ecological niche occupation when compared to earlier Late Cretaceous pterosaurs (Santonian to Campanian faunas).  This study also indicates that when it came to developing large body forms, the Pterosauria were able to outcompete coeval birds.

The Fossilised Partial Ulna of the Sidi Chennane Specimen

Picture credit: PLOS Biology

Key

ut = ulna tubercle, vp = ventral process

A 5% Increase in Known Pterosaur Species

Co-author of the study, Dr Brian Andres, from the Jackson School of Geosciences at The University of Texas at Austin, commented:

“The Moroccan fossils tell the last chapter of the pterosaurs’ story – and they tell us pterosaurs dominated the skies over the land and sea, as they had for the previous 150 million years.”

With around 130 pterosaur species described to date, these fossils from Morocco have led to a 5 percent increase in the known number of flying reptile species.  This diversity of pterosaur species from Upper Maastrichtian deposits in Morocco suggest an abrupt mass extinction of the Pterosauria at the Cretaceous-Palaeogene boundary.

The scientific paper: “Late Maastrichtian Pterosaurs from North Africa and Mass Extinction of Pterosauria at the Cretaceous-Paleogene boundary” by Nicholas R. Longrich, David M. Martill and Brian Andres published in PLOS Biology.

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

Visit the award-winning Everything Dinosaur website: Everything Dinosaur.

Basal Ankylosaurine Dinosaur Jinyunpelta is Described

Scientists, including researchers from the Chinese Academy of Sciences have published details of a new genus of club-tailed, armoured dinosaur that roamed China around 100 million years ago.  The dinosaur has been named Jinyunpelta sinensis, it represents the first definitive ankylosaurid dinosaur from southern China.

An Illustration of the Basal Ankylosaurine Jinyunpelta sinensis

Picture credit: The Chinese Academy of Sciences

Two Fossil Specimens of Jinyunpelta sinensis

This new dinosaur, very distantly related to Late Cretaceous ankylosaurs like Euoplocephalus and Ankylosaurus (from which the group is named), has been described based on two fossil specimens.  The fossils come from Jinyun County, Zhejiang Province, China and have been excavated from rocks which form part of the Liangtoutang Formation, which covers the important boundary between Lower and Upper Cretaceous sediments (Albian faunal stage to the Cenomanian faunal stage of the Cretaceous).

The fossil material consists of an almost complete skull, parts of the jaw and postcranial remains including a beautifully-preserved tail club.

The Skull and Jaw of Jinyunpelta sinensis

Picture credit: The Chinese Academy of Sciences/Scientific Reports

The generic name derives from “Jinyun” (Mandarin) honouring Jinyun County where the fossils were found and “pelta” (Latin), a small shield, in reference to the osteoderms found on all ankylosaurians.  The root of the specific name “sin” (Greek) refers to China, the country of origin.

Photographs and Line Drawings of the Spectacular Tail Club

Picture credit: The Chinese Academy of Sciences/Scientific Reports

The Oldest Swinger in Town

J. sinensis is described as a basal ankylosaurine dinosaur and it represents the oldest and the most basal ankylosaurian known to have a well-developed tail club knob.  It is quite a sizeable bony club too, getting on for nearly half a metre across at its widest part.  The researchers conclude that large and highly modified tail clubs evolved at the base of the ankylosaurine at least about 100 million years ago.

Jinyunpelta possesses unique cranial features which differentiates this Chinese dinosaur from other armoured dinosaurs known from the northern hemisphere, these autapomorphies support the establishment of a new genus.  Several other types of ornithischian dinosaur have been reported from this part of China, including another armoured dinosaur – a  nodosaur and basal ornithopod that was named and described in 2012 (Yueosaurus tiantaiensis)

The discovery of Jinyunpelta expands the known diversity and palaeogeographical distribution of ankylosaurians in Asia.

The scientific paper: “The Most Basal Ankylosaurine Dinosaur from the Albian–Cenomanian of China, with Implications for the Evolution of the Tail Club” by Wenjie Zheng, Xingsheng Jin, Yoichi Azuma, Qiongying Wang, Kazunori Miyata & Xing Xu published in the open access journal “Scientific Reports”.

Visit the Everything Dinosaur website: Everything Dinosaur.