Columbian Giant Crocodile – Anthracosuchus balrogus

Vertebrate fossils from a coal mine in north-eastern Columbia have provided palaeontologists with a fascinating insight into life in the tropics in the first few million years after the Cretaceous mass extinction event.  The dinosaurs may have gone but preserved in the Cerrejón Formation are the remains of giant reptiles who were the apex predators within this rainforest community.  A paper has just been published in the scientific journal “Historical Biology” that reports on the discovery of yet another large crocodile genus from this locality, one that probably preyed upon giant turtles, it in turn may have been hunted by Titanoboa, the largest snake known to science.

“Living Fossils”

Crocodiles may be referred to as “living fossils”, a term that most palaeontologists dislike as it suggests that organisms do not change much over time.  True, the basic body plan (bauplan) of the crocodilians may not have changed much since the early Mesozoic, but the fossil record shows that crocodiles evolved to occupy a vast array of ecological niches.  This new discovery, a crocodile named Anthracosuchus demonstrates this as it had a blunt, short snout, in direct contrast to its long-snouted close relatives.

The new species lived in what was an inland, freshwater environment, an extensive tropical floodplain that was covered in dense jungle and crossed by a number of large rivers which led into the nascent Caribbean Sea.  South America was an island, there was also a substantial marine intrusion to the west of the Cerrejón Formation, this marine environment stretching into what is now central Bolivia.  Reptiles dominated the ecosystem and at 4.8 metres in length Anthracosuchus, with its very powerful jaws was probably a top predator.

 Views of Skull Material Ascribed to this Genus (A. balrogus)

A crocodile with a blunt, broad snout.

Picture credit: Alexander K. Hastings et al

Anthracosuchus balrogus

The picture above shows two of the four fossil skulls assigned to this new genus.  The top images are a view of the skulls looking down onto them, viewing the top (dorsal view), the two images underneath are views of the underside of the skulls (ventral view).  All the fossil material including limb bones, teeth and osteoderms (armoured scales) were excavated from a clay layer immediately below a layer of coal in the Cerrejón mine.

The fossils date from 58-60 million years ago (Palaeocene).  This crocodile has been classed as a member of the dyrosaurid crocodiles, a widely dispersed group of Late Cretaceous/Palaeocene crocodiles that, for the most part are marine and characterised by long, narrow snouts.  Here is a member of the Dyrosauridae, with a very different snout and one from strata laid down inland.  These types of crocodile are now extinct, it is believed an ancestor of the dyrosaurids was the mighty Sarcosuchus whose fossils are associated with Cretaceous aged strata from Niger (Africa).

Discovered in 2005

The first skull of this new dyrosaurid was discovered in 2005, but the skull was missing its front end.  The back of the skull indicated that this type of crocodile probably had a blunt, short snout.  This was confirmed in 2007 when a second skull, this time with its front end intact, was found.  Two more skulls were excavated later on that year, making the total number of individuals known to be at least four.

The new species of crocodile was discovered by a team of University of Florida researchers, led by Jonathan Bloch, Associate Curator of Vertebrate Palaeontology at the Florida Museum of Natural History, Alexander Hastings (Florida Museum of Natural History), assisted by Carlos Jaramillo, a palaeobotanist with the Smithsonian Tropical Research Institute.  All specimens of the new taxon are deposited at the Museo Geológico José Royo y Gómez, Colombian Geological Survey, Bogotá, Colombia.  Casts of these specimens are also deposited at the collections of the Florida Museum of Natural History.

“Coal Crocodile”

Anthracosuchus means “coal crocodile”, a reference to the fossil remains being found adjacent to a coal seam.  The trivial or specific name is derived from “Balrog”, a fiery demon that features in Tolkien’s “Lord of the Rings”.  Balrog inhabited the deep mines of Moria, so since this crocodile’s fossils have been found in a mine, the trivial name is very apt.

A number of crocodile fossils have been found at the Cerrejón site, to read about the discovery of another, related crocodile species: New Crocodile Species in Columbian Mine.

Remains of turtle shells, discovered in close proximity to the crocodile fossils, show signs of damage.  There are scratches, most likely made by teeth and also at least one example of a healed bite mark.  The scratches and bite marks match the profile of the teeth of A. balrogus, this suggests that this crocodile, related to long-snouted dyrosaurids, adapted to an inland habitat and a diet of turtles.

 Fossilised Turtle Carapace Showing Traces of Crocodile Bites

Was this damage caused by a hungry Anthracosuchus?

Picture Credit: Alexander K. Hastings et al

The picture above shows a fragment of shell (A) and a line drawing (C) viewed from above (dorsal view).  Picture B and the line drawing D, are the same fragment but this time, viewed from below (ventral view).  Potential bite marks (bm) and bone regrowth after a bite (bm&p) are illustrated.

Damage to a Turtle Shell

Picture E and line drawing G are of a fragment of turtle shell viewed from the top that shows further damage, once again bite marks (bm) are indicated.  Picture F and its associated line drawing H show another fragment, bite marks and drag marks (dm) are illustrated.  Picture I and drawing J show a tooth from Anthracosuchus balrogus is analogous to the damage seen on the turtle shell fragments.  Image J and L shows a turtle fragment viewed from the top (dorsal) with bite marks.

Coeval with Titanoboa

This crocodile certainly had a very powerful bite, however, it shared its environment with the largest snake known to science, the immense Titanoboa (T. cerrejonensis).  At more than three times the size of Anthracosaurus this constrictor may have preyed upon adult crocodiles.  Anthracosaurus in turn, may have hunted and eaten immature Titanoboas.  Battles between these large reptiles would have been a spectacular sight.

Titanoboa Tackles a Large Anthracosuchus

Titanoboa tackles the short-snouted Anthracosuchus.

Picture credit: Florida Natural History Museum

To read about the discovery of Titanoboa: Titanoboa – Giant Prehistoric Snake of the Palaeocene.

The Dyrosauridae are one of the very few types of large, marine reptile that survived the Cretaceous mass extinction event.  The discovery of a broad-snouted genus in South America will help scientists to identify how these creatures adapted to new environments.  It will also help them to piece together how these crocodiles dispersed across much of the globe from their African origins.  Fossil evidence suggests that during the Cretaceous, when the Atlantic ocean was not as wide as it is today, there were a number of dispersals of marine dyrosaurid crocodiles from Africa to the Americas. This trend seems to have continued into the early Cenozoic, with migrations east to west during the Palaeocene epoch.

Researchers Map the Dispersal of Dryosaurid Crocodiles from Africa

Dispersal and resulting distribution of dyrosaurid crocodiles.

Picture credit: Alexander K. Hastings et al

“Pinocchio rex” Qianzhousaurus sinensis – A new Look for the Tyrannosaurs

Over the last two days or so, there has been a lot of media coverage regarding the discovery of a long-snouted member of the tyrannosaur family, a fearsome, carnivorous dinosaur that has been named Qianzhousaurus sinensis.  The fossil discovery is very significant as it establishes the presence of long-snouted tyrannosaurs nestling somewhere amongst the Tyrannosauridae family.  Quite where they fit is still up for debate as the phylogeny of this group is becoming more and more complicated as new genera are described.  Phylogenetics looks at the evolutionary history of a species or group of organisms, it aims to map out lines of descent and taxonomic relationships.

Qianzhousaurus sinensis

This new tyrannosaur nick-named “Pinocchio rex” due to its long snout, has led to the establishment of a new branch of the tyrannosaur family. Living alongside the bone crushing apex predators that were the deep-skulled tyrannosaurs, there was another closely related group, meat-eaters that probably hunted different sorts of prey and fed in a different way.  This new sub-branch or clade of tyrannosaurs has been named the Alioramini (pronounced Al-ee-oh-ram-min-eye), as for the moment it contains just two genera, Alioramus and the newly described Qianzhousaurus.

Alioramus also had a long, narrow snout.  The genus name translates as “other evolutionary branch”, as ever since Alioramus was discovered, palaeontologists had suspected that there was a sub-branch of the tyrannosaur family tree.  The fossils of Qianzhousaurus go a long way in helping to strengthen this hypothesis.

Long-Snouted Fearsome Tyrannosaur – Qianzhousaurus sinensis

New long-snouted tyrannosaur.

Picture credit: Junchang Lü/Chinese Academy of Geological Sciences

The picture above shows three views of the partial skull and upper jaw of Q. sinensis.  The first picture shows a view from the side (lateral), the second picture shows a view looking down onto the fossil (dorsal) and the third picture shows the view from the underside (ventral).  The scale bar represents five centimetres.

Scientific Paper Published

In a paper published this week in the journal “Nature Communications”,  the authors which include Stephen Brusatte (Chancellor’s Fellow in Vertebrate Palaeontology at the University of Edinburgh) and Junchang Lü (Institute of Geology at the Chinese Academy of Geological Sciences), describe this Theropod as a “remarkable find”.  It is indeed, but the story of this fossil’s discovery is also very remarkable.

Back in the late summer of 2010, construction workers helping to build a new industrial park close to the city of Ganzhou in Jiangxi Province (south-eastern China), uncovered the remains of two dinosaurs.  One was a small oviraptorid, the second and much more spectacular find represented a substantial meat-eater.  The works foreman telephoned a local fossil hunter who visited the site and having examined some of the finds and realised their importance, called in the Ganzhou city Mineral Resources Management Department.  A field team was quickly despatched and within a few hours the vast majority of the exposed fossil material was collected, which in the case of the large theropod represented much of the skull and jaws, vertebrae, parts of the pelvis and limb bones.

Late Cretaceous “Hotbed”

Many different types of dinosaur have been found in the sedimentary rocks that are exposed in and around Ganzhou city, it is often described as a “hotbed” for Late Cretaceous dinosaur discoveries.  The field team had to work fast, as a number of fossil dealers had also heard of the discovery and if they had got to the bones first, then the fossilised remains could have ended up being sold on the black market.

As things turned out, following the speedy collection, the story of Qianzhousaurus slowed down to a snail’s pace.  The fossils which had been bagged up remained with the Mineral Resources Management Department for the best part of eight months, before they were presented to the Ganzhou Natural History Museum.  In August 2012, the museum assembled a team of Chinese scientists and technicians to examine the bones and begin the reconstruction of the specimen.

Close Phylogenetic Relationship with Alioramus

The initial research work was concluded in January of last year and the full significance of the discovery was realised.  Here was an adult tyrannosaur that exhibited skull characteristics that placed it in a close phylogenetic relationship with the tyrannosaur known as Alioramus.  This was proof that the long suspected sub-branch of long-snouted tyrannosaurs had existed.

Further work was undertaken and the formal academic paper published this week.  Say hello to Qianzhousaurus sinensis.  Qianzhousaurus is pronounced Chy-an-shoe-sore-us, the genus name is derived from the old name for the city of Ganzhou (Qianzhou), the species name reflects that this dinosaur was Chinese.

An Illustration of the Late Cretaceous Tyrannosaur Q. sinensis

New tyrannosaur described – Qianzhousaurus sinensis.

Picture credit: Chuang Zhao

This dinosaur had a number of small horns or bumps running along its snout.  It is illustrated attacking a feathered oviraptorid dinosaur, as the fossils of Qianzhousaurus sinensis were found in association with the bones of a small member of the Oviraptoridae family.

Dr Brusatte explained:

“This is a different breed of tyrannosaur.  It has the familiar toothy grin of T. rex, but its snout was much longer and it had a row of horns on its nose.  It might have looked a little comical, but it would have been as deadly as any other tyrannosaur, and maybe even a little faster and stealthier.”

This specimen is very significant as the fused skull bones identify it as an adult animal. Qianzhousaurus probably weighed around 1,000 kilogrammes and reached lengths of around 8-9 metres.  Smaller than its deep-skulled tyrannosaur contemporaries, Qianzhousaurus probably occupied a niche in the Late Cretaceous food chain, that of a secondary predator.  Even if it lived in packs, it probably did not specialise in hunting really large herbivorous dinosaurs.  It was nowhere near as powerful as some of the other Upper Cretaceous tyrannosaurs known from Asia, the likes of Tarbosaurus and the recently described Zhuchengtyrannus.

Tyrannosaur Skull Comparisons (T. rex versus Q. sinensis)

Scale bar = 5cm

Picture credit: Journal of Nature Communications and Everything Dinosaur

To read an article about Zhuchengtyrannus: New Species of Asian Tyrannosaur Announced.

Studying Tyrannosaurs

The bite force that this predator could generate was nowhere near the bone crushing bite force of Tyrannosaurus rex.  This was a more graceful, agile hunter, perhaps stalking feathered dinosaurs and other reptiles.  Consider Qianzhousaurus as the leopard that shares the same habitat as a lion.

For models and replicas of Qianzhousaurus, numerous tyrannosaurs and other prehistoric animals: PNSO Age of Dinosaurs Models.

This fossil is very important for a number of reasons, firstly there is a substantial amount of fossil material to study, scientists can learn more about the tyrannosaur family as a result.  Secondly, unlike the two known Alioramus specimens which both represent juveniles, this adult animal demonstrates that there were long-snouted forms of Tyrannosauridae.  A sub-branch of tyrannosaurs did exist and the presence of a long-snout in the likes of the Alioramus specimens cannot be attributed to the fact that these not fully grown dinosaur specimens “hadn’t filled out yet” as a colleague puts it.

Thirdly and perhaps most crucially of all, this fossil discovery from south-eastern China was found in Upper Cretaceous deposits located more than two thousand kilometres away from the Upper Cretaceous deposits that yielded the Alioramus material.  It seems that the long-snouted tyrannosaurs were widely distributed in Asia during the last few million years of the Cretaceous period.  This means that there are, very probably a number of other “Pinocchio rex” tyrannosaurs awaiting discovery.

We wonder what Geppetto would have made of it all…