New Species of Diplodocid Dinosaur – Galeamopus pabsti

Writing in the academic journal “Peer J”, palaeontologists Emanuel Tschopp and Octávio Mateus (Universidade Nova de Lisboa), have identified a new species of diplodocid dinosaur within the Galeamopus genus.  The dinosaur has been named Galeamopus pabsti. The fossils, which come from the Upper Jurassic Morrison Formation, specifically the Howe-Scott Quarry in the northern Bighorn Basin in Wyoming, (USA), further demonstrate the diversity of sauropods associated with the Late Jurassic fauna of western North America.

A New Species of Diplodocid Dinosaur

A life reconstruction of G. pabsti.

Picture credit: Davide Bonadonna with additional annotation by Everything Dinosaur

The Galeamopus Genus

Excavation began in 1995, by a Swiss field team led by palaeontologists Dr Hans-Jakob ‘Kirby’ Siber and Dr Ben Pabst (The Dinosaur Museum (Sauriermuseum) in Aathal, Switzerland).  The trivial name, honours Dr Pabst in recognition of his contribution to dinosaur fossil preparation and exhibition mounting.

This is the second member of the Galeamopus genus to be identified, the first species G. hayi, was erected in 2015, when Emanuel Tschopp and Octávio Mateus, along with colleagues from Oxford University and the Raymond M. Alf, Museum of Palaeontology, (Claremont, California, USA), published a paper that resurrected the genus Brontosaurus following an extensive review of the Diplodocidae.

For an article on the 2015 paper: The Return of Brontosaurus.

Nearly Complete Fossil Specimen Just Missing the Tail

Importantly, much of the skull, although broken apart, was collected along with around the majority of the anterior portion of the skeleton.  The presence of fossilised wood and freshwater bivalves indicated that this individual had come to rest in a stream channel.  The skull has helped to assign a new species within the Galeamopus genus and the robust limb bones, such as the very sturdy upper arm bone (humerus), helps to distinguish the Galeamopus genus from the more gracile and slender Diplodocus.

Dr Emanuel Tschopp, who holds a number of academic posts including a position at the University of Turin, commented that the bones represent a young adult and that this dinosaur could have reached lengths in excess of twenty-seven metres.  Bite marks on the ribs and shed theropod teeth found in association with the bones suggest that the dinosaur’s carcase was scavenged before it was finally buried.

A Late Jurassic Scene – Galeamopus pabsti Scavenged by Theropods

The carcase of Galeamopus is scavenged by an Allosaurus whilst two smaller Ceratosaurus approach.

Picture credit: Davide Bonadonna

Galeamopus pabsti

Dr Tschopp stated:

“Diplodocids are among the best-known sauropod dinosaurs.  Numerous specimens of currently fifteen accepted species belonging to ten genera have been reported from the Late Jurassic to Early Cretaceous of North and South America, Europe, and Africa.  However, the highest diversity is known from the Upper Jurassic Morrison Formation of the western United States, a recent review [the 2015 paper] recognised twelve valid, named species, and possibly three additional, yet unnamed ones.”

A View of the Reconstructed Skull of Galeamopus pabsti

A right lateral view of the reconstructed skull of G. pabsti.

Picture credit: Emanuel Tschopp and Octávio Mateus

A Long Tail?

Although, the tail bones are missing, the scientists are confident that like all the other diplodocids, Galeamopus pabsti had a long tail, which in this case, represents more than half of the animal’s total body length.  This long whip-like tail may have been used to help herd members keep in contact with each other or perhaps it had a role in defence.  If attacked these dinosaurs might have lashed out with their tails, or perhaps moved them so quickly that they would have made a sonic boom (breaking the sound barrier).

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Chenanisaurus barbaricus – Substantial Abelisaurid from Late Cretaceous Morocco

One of the last types of dinosaur to have existed in north Africa has been described in a new scientific paper published in the journal “Cretaceous Research”.  A fragment of jaw bone (dentary) and isolated teeth discovered in a phosphate mine at Sidi Chennane in the Oulad Abdoun Basin, (Morocco), has enabled scientists to identify a new species of abelisaurid.  The dinosaur, named Chenanisaurus barbaricus may belong to an as-yet undescribed family of Abelisaurs unique to Africa.

An Illustration of the Late Cretaceous Abelisaurid Chenanisaurus barbaricus

An illustration of Chenanisaurus barbaricus.

Picture credit: University of Bath with additional annotation by Everything Dinosaur

A Blunt Snout with an Unusually Short and Robust Jaw

Analysis of the fragment of dentary, along with the associated teeth, indicates that the jaw of this dinosaur was very short, even for an abelisaurid.  The morphology of the jaw is described as being even more extreme than that seen in other abelisaurids such as Carnotaurus.  Extensive wear on the teeth suggests hypercarnivory (diet consisting of more than 70 percent meat), Chenanisaurus was around 7-8 metres in length and it may have been an apex predator within the Late Cretaceous ecosystem.

A Photograph Showing Two Views of the Jaw Fragment

Jaw fragment fossil (labial and buccal view).

Picture credit: University of Bath

Marine Deposits from a Phosphate Mine

Lead author of the scientific paper, Dr Nick Longrich (Milner Centre for Evolution at the University of Bath), along with colleagues from Morocco, France, and Spain studied the jaw fossil and teeth that had been found in 66-million-year-old strata in a phosphate mine located in northern Morocco.  Dinosaur fossils from the end of the Cretaceous (Maastrichtian faunal stage) are exceptionally rare in north Africa.  Rising sea levels had isolated Africa as the super-continent of Gondwana continued to break up and from about 95 million years onwards, much of the former terrestrial habitat of the Dinosauria in north Africa was lost to the sea.

Commenting on the rarity of the fossil find, Dr Longrich stated:

“This find was unusual because it’s a dinosaur from marine rocks – it’s a bit like hunting for fossil whales, and finding a fossil lion.  It’s an incredibly rare find – almost like winning the lottery.  But the phosphate mines are so rich, it’s like buying a million lottery tickets, so we actually have a chance to find rare dinosaurs like this one.”

Chenanisaurus barbaricus – Confirming a Distinct African Terrestrial Fauna

Not only was Chenanisaurus barbaricus one of the last dinosaurs to roam our planet, its discovery supports the idea of a distinct north African terrestrial fauna towards the end of the Age of Dinosaurs.  During the Maastrichtian faunal stage of the Late Cretaceous, horned dinosaurs and hadrosaurids were the most common and specious large, plant-eating dinosaurs in North America and Asia, whereas a different group of dinosaurs dominated terrestrial ecosystems in South America, India and Madagascar (Titanosauriformes and abelisaurids).  In North America and Asia, the dominant, apex predators were Tyrannosaurs.

In 2004, a paper published in the “Journal of African Earth Studies”, provided details of a right hindlimb (femur, tibia and fibula), that had been found in phosphate deposits near the town of Khouribga (central Morocco).  Just like Chenanisaurus, these fossils date from approximately 66 million years ago and were also found in marine rocks.

Team members at Everything Dinosaur are not aware of a new genus having been established as a result of the discovery of the leg bones, but their presence in the rocks does indicate that titanosaurids survived in north Africa until the very end of the Cretaceous.  These fossils along with the Chenanisaurus material suggests the persistence of a classic Gondwanan abelisaurid/titanosaurid fauna in mainland Africa right up to end- Cretaceous extinction event.

Tyrannosaurid versus Abelisaurid Distribution

Tyrannosaurid versus abelisaurid distribution. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Key

Tyrannosaurids = green

Abelisaurids = brown

The picture above shows a general distribution of apex predatory dinosaurs in the Late Cretaceous, with the exception of southern Europe, tyrannosaurids dominated the apex predator positions in Laurasia, whilst the abelisaurids dominated in the regions that made up Gondwana.

Phylogenetic Analysis

Phylogenetic analysis undertaken by the research team suggests that Chenanisaurus may represent a lineage of abelisaurids that is distinct from those previously described from the latest Cretaceous of South America, Indo-Madagascar, and Europe, consistent with the hypothesis that the fragmentation of Gondwana led to the evolution of endemic dinosaur faunas during the Late Cretaceous.

Dr Longrich added:

“We have virtually no dinosaur fossils from this time period in Morocco, it may even be the first dinosaur named from the end-Cretaceous of Africa.  It’s also one of the last dinosaurs in Africa before the mass extinction that wiped out the dinosaurs.  It is an exciting find because it shows just how different the fauna was in the Southern Hemisphere at this time.”

Visit Everything Dinosaur’s website: Everything Dinosaur.

French Revolution for the Brachiosauridae

This week there have been a number of papers published announcing newly described dinosaurs.  In time, we will get around to writing about several of them, but first, let’s take a look at the basal brachiosaurid Vouivria damparisensis, which has been described from fossil material representing a single animal that was first discovered back in 1934.

Earliest Relative of Brachiosaurus from north-eastern France

A newly described basal brachiosaurid Vouivria damparisensis.

Picture credit: Imperial College London

Vouivria damparisensis

Writing in the journal “Peer J”, lead author Dr Philip Mannion (Dept. of Earth Science and Engineering at Imperial College, London) and his co-workers Ronan Allain (Natural History Museum, Paris) and Oliver Moine (Laboratory of Physical Geography, CNRS / University Paris 1 Panthéon-Sorbonne), propose that these fossils represent the earliest known brachiosaurid, a family of dinosaurs that include such well-known animals as Brachiosaurus and Giraffatitan.  However, despite the high profile (no pun intended), of “arm lizard” in particular, surprisingly, very little is known about the evolution of these sauropods, Vouivria helps to fill in some significant gaps.

A Photograph of a Dorsal Vertebra from Vouivria damparisensis

A dorsal vertebra of Vouivria.

Picture credit: Peer J

The picture above shows a bone from the spine of V. damparisensis.  The bone comes from the front part of the dorsal vertebrae, (A) left lateral view, (B) right lateral view, (C) anterior view; (D) ventral view. Scale bar equals five centimetres.

Middle/Late Oxfordian Sauropod

The Brachiosauridae seem to have had their heyday in the Late Jurassic, Vouivria is important as relatively few sauropods are known from rocks of this age.  Most Sauropod fossils from the Jurassic are associated with rocks that were laid down in the latter stages of this geological period, namely during the Kimmeridgian–Tithonian faunal stages.  Vouivria damparisensis comes from strata that is several million years older, having lived around 160 – 158 million years ago.  In addition, it is known from relatively complete remains.

Contrast this with the UK’s Late Jurassic sauropod fossil material, in particular the likes of Duriatitan (D. humerocristatus), which like Vouivria, has been assigned to the Titanosauriformes, the clade of long-necked dinosaurs to which the Brachiosauridae family belongs.  Duriatitan is known from a single fossil bone (left femur) and this fossil, which comes from Dorset, was found in rocks that are believed to be about four million years younger than the rocks in which Vouivria was discovered.

At an estimated 15 tonnes and some 15 metres in length, Vouivria was a sizeable beast.  It is likely that this dinosaur fed on the upper storeys of pine trees and Araucaria, using its long neck to reach parts of trees that other herbivorous dinosaurs could not reach.

An Illustration of a Typical Brachiosaurid

A colourful Brachiosaurus dinosaur model.

Picture credit: Everything Dinosaur

The model featured above is from the: Wild Safari Prehistoric World Models.

Revolutionising the Brachiosauridae Family Tree

The researchers were able to conduct an analysis of the Brachiosauridae family tree and an assessment of the evolutionary relationships indicates that by the Early Cretaceous, brachiosaurids were restricted to Africa and the United States.  They were probably extinct in Europe.

Furthermore, the team were able to postulate that fossils that most likely represent brachiosaurids are only known from the USA, Africa and western Europe.  Previously, studies examining the fossils of another long-necked dinosaur, Padillasaurus (P. leivaensis), from Lower Cretaceous rocks of Columbia, had suggested that Padillasaurus was a brachiosaurid.  The detailed description of Vouivria casts doubt on this suggesting that Padillasaurus was not a member of the Brachiosauridae and that as a result brachiosaurids remain unknown from South America.  Padillasaurus is placed within the Somphospondyli, another clade of Titanosauriformes, related to the brachiosaurids, but one with a much more global distribution.

A Modified Map Showing the Original Location of the Fossil Bones at the Dig Site

A map showing the position of the bones at the original dig site.

Picture credit: Peer J modified from Dorlodot (1934)

Building upon the original 1934 description (Dorlodot) and the subsequent reassessment of the fossil material Lapparent (1943), before the fossil material was confined to storage, the researchers have provided a valuable insight into the radiation and geographical spread of brachiosaurids.  The current fossil evidence suggests that this type of sauropod spanned the Late Jurassic (Oxfordian) through to the Late Albian/Early Cenomanian of the Cretaceous.  The last of the brachiosaurids lived in what is now known as the United States and it is likely that by the earliest Late Cretaceous (approximately 98 million years ago), the Brachiosauridae were extinct.

A Better Understanding of the Palaeoenvironment

The scientific paper provides a better understanding of how the remains of the dinosaur were preserved.  During this period of Earth’s history, much of what we now know as western Europe consisted of a series of low-lying tropical islands.  The earlier studies had concluded that as the rocks in which this dinosaur was found originally come from a coastal environment, then the corpse of Vouivria was probably washed out to sea.  More detailed analysis of the surround rocks and sediments tell a different story.  The researchers conclude that Vouivria died in a lagoon, a habitat that existed during a brief decline in sea levels.  When sea levels rose again, the carcase was buried.

Commenting on the importance of these fossils, lead author of the study Dr Philip Mannion (Imperial College London), stated:

“We don’t know what this creature died from, but millions of years later it is providing important evidence to help us understand in more detail the evolution of brachiosaurid sauropods and a much bigger group of dinosaurs that they belonged to, called Titanosauriformes.”

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