Torvosaurus gurneyi – Monster Megalosaur from Portugal

The scientific paper has just been published that permits a new species of Torvosaurus to be announced to the world.  Torvosaurus means “savage lizard” and joining Torvosaurus tanneri, a meat-eating dinosaur known from the famous Upper Jurassic Morrison Formation of the United States, is T. gurneyi from the Lourinhã Formation of central west Portugal.  Based on the size of the skull material and using other fragmentary fossils from the Lourinhã Formation that had been found previously, palaeontologists estimate that this dinosaur measured around ten metres in length and weighed between four and five tons.

Torvosaurus

Based on these dimensions, this dinosaur can lay claim to the title of being one of Europe’s largest meat-eating dinosaurs described to date.

“Savage Lizard” Torvosaurus gurneyi Apex Predator of the Late Jurassic of Europe

Top predator of Portugal from the Late Jurassic.

Picture credit: Sergey Krasovskiy

Authors of the scientific paper, Professor Octávio Mateus and Christophe Hendrickx of the Museu da Lourinhã, (Lourinhã, Portugal), which has just been published on line in PLoS One, collated the known fossil material ascribed to Torvosaurus spp. found in Portugal and thanks to the discovery of part of a skull and jaws, they are able to distinguish this species from the Torvosaurus known from the United States.

Lourinhã Fossils

A study of the fossils from Lourinhã reveal a number of differences between them and the North American fossil material.  For example, the near complete left maxilla ( a bone from the upper jaw), was found in Portugal by the Dutch amateur fossil collector Aart Walen in 2006.  It was carefully prepared and it was the finding of this fossil that really gave the Portuguese scientists the opportunity to compare their material with the fossils of Torvosaurus tanneri.

The maxilla in large theropod dinosaurs can be very characteristic, it helps to determine affinities amongst meat-eating dinosaurs and, importantly in this case, can help palaeontologists identify a new species.  When the Portuguese maxilla was compared to the maxilla of a Torvosaurus tanneri the researchers were able to point out some subtle differences.  For example, the maxilla of the Portuguese specimen had fewer teeth (less than eleven), this and other anatomical differences permitted the team to create a distinct Portuguese species of Torvosaurus.

Comparing the Left Maxilla of T. gurneyi with T. tanneri

Torvosaurus jaw bones compared.

Picture credit: Journal PLoS One with additional notation by Everything Dinosaur

Torvosaurus tanneri

Although closely related to Torvosaurus tanneri, this new predator lived thousands of miles away on the eastern tip of the Eurasian and African landmass.  The species name honours the American artist and illustrator James Gurney who created the “Dinotopia” series of books all about a magical land where dinosaurs and people live together.  James Gurney was born in California and so from a geographical perspective he is much closer to the Torvosaurus known from the United States than from this new European dinosaur.

A Scale Drawing Giving the Approximate Size of T. gurneyi

A scale drawing of Torvosaurus.

Picture credit: Journal PLoS One/Scott Hartman (A) with additional skull drawing by Simão Mateus (B)

The drawing above gives an approximate size estimate for this new species of carnivorous dinosaur.  The maxilla is shaded red in drawing (A) and the scale bar is approximately 1 metre.  The other parts of the skeletal drawing shaded blue refer to fragmentary fossil material found previously that has been assigned to Torvosaurus gurneyi.  The skull drawing (B) indicates the position of the holotype left maxilla (ML1100) in relation to the rest of the skull.  The scale bar represents 10 centimetres.  Torvosaurus gurneyi has been assigned to the megalosaur family.

Trackway

A trackway with individual prints measuring up to seventy-nine centimetres in length has been assigned to this new species.  Although it is very difficult to tie down the fossil print to a species, there is no other known Portuguese theropod of comparable size so these trace fossils have been attributed to T. gurneyi.  Dinosaur eggs and some fossilised embryos from the Sobral Member of the Lourinhã Formation have also been attributed to this new dinosaur species.

The fauna and flora of the Iberian area of Europe in the Late Jurassic was very similar to that found in the western United States, as epitomised by the Morrison Formation.  Both the Morrison Formation and the Lourinhã Formation sediments were laid down at approximately the same time, these strata cover the Late Oxfordian, the Kimmeridgian and the Early Tithonian faunal stages of the Late Jurassic.  However, during this period in Earth’s history the continents of North America and Europe were already separated by an intercontinental sea (the early Atlantic).

Professor Mateus and his colleagues put forward an hypothesis a few years ago now, that suggested that during the Early Oxfordian and the preceding faunal stage of the Late Jurassic, the Callovian, uplift of continental plates formed temporary land bridges between Europe and the Americas.  This allowed an exchange of terrestrial faunas between the United States and Iberia.  When these land bridges were lost as sea levels rose, these two, now separate ecosystems which shared common ancestors were left to evolve in isolation.

Footnote

At Everything Dinosaur we are aware of the hyperbole that has surrounded the publication of the scientific paper on Torvosaurus gurneyi. It is certainly an impressive dinosaur and we do not dispute the size estimates (extrapolated from inferred skull size and skull size to body ratio) along with assigned limb bones and such like.  The left maxilla (ML1100) shows enough characteristics to allow a new species to be created, but the title of “Europe’s largest meat-eating dinosaur described to date”, is easier to justify than some of the other headlines used in articles.

For example, we have come across the misleading headline “Europe’s biggest dinosaur”, this is simply not true, many herbivorous dinosaurs were much bigger than Torvosaurus spp. and there are a number of fragmentary remains of meat-eating dinosaurs that could challenge the claim made by other writers that T. gurneyi is Europe’s biggest meat-eating dinosaur.  For example, the specimen of Baryonyx walkeri from the Wealden Clay of south-east England was not fully grown when it died and it could have potentially rivalled Torvosaurus in size.

For models and replicas of European dinosaurs including Torvosaurus, whilst stocks last: CollectA Age of Dinosaurs Deluxe Models.

The Daohugou Biota – China 160 Million Years Ago

A team of international researchers based at the Chinese Academy of Sciences have identified a stratigraphic sequence of Middle Jurassic deposits thanks to fossils of a salamander.  The huge assemblage of vertebrate fossils and other material has provided scientists with an exquisite insight into an ecosystem that thrived in north-eastern China around 160 million years ago.  The series of highly fossiliferous sites are being linked into one large group of sedimentary material that can be put together in terms of their geological age thanks to the common range of fossils these different locations contain.

Sequence of Deposition

The locations (six in total scattered across the provinces of Hebei and Liaoning), are described as the Daohugou Biota.  They form part of the Tiaojishan Formation (or at least most of the locations seem to do so), but importantly, the strata has been recognised as being much older than the Jehol Biota.  The Jehol Biota is associated with Lower Cretaceous deposits (Barremian and Aptian stages of the Early Cretaceous), however, the Daohugou Biota is dated to around the Bathonian faunal stage of the Middle Jurassic.

The Jehol Biota

The Jehol Biota epitomised by the wonderfully well preserved fossil remains of Liaoning Province, is famous for its feathered primitive bird and feathered theropod dinosaur fossils representing an ecosystem that consisted of a series of large lakes, forests and nearby volcanoes.  Periodically, the volcanoes would erupt, bury large areas of the surrounding landscape with ash and devastate the fauna and flora.

The fine grain sediments that were deposited helped preserve fossils in amazing detail.  At first, all the fossils from this part of China were thought to be of Lower Cretaceous age, after all, such beautifully preserved fossils are exceptionally rare, but it now seems that prior to the environment which formed the Jehol Biota and fossil assemblage, there existed in the same location but around 30 million years earlier another ecosystem which has been preserved in equal detail thanks again to volcanic activity.

Identifying the Biota

Just like their Jehol Biota counterparts, the Daohugou theropod dinosaurs are feathered, with a lot of anatomical detail preserved thanks to the fine lacustrine (lake) beds in which the fossils are found.  Something like 142 different vertebrate species have been identified from the Jehol Biota, pterosaurs, feathered and non-feathered dinosaurs, amphibians, fish, lizards and of course primitive birds.  The authors of a new study, which confirm the Midddle Jurassic age of the Daohugou Beds have documented at least thirty different vertebrate taxa to date, including two lizards, a tadpole from a frog, five dinosaurs, four early mammals and thirteen pterosaurs.

No Birds Found

Intriguingly, no birds, however, this may not be so much of a surprise as birds may not have evolved at the time of deposition of the first fossil assemblage.  What is known for certain is that a number of the dinosaur species identified to date from the Daohugou Beds are very similar to birds, Anchiornis for example, was extremely bird-like.

To read an article on the discovery of Anchiornis: Older than Archaeopteryx – Dinosaurs on their Way to Becoming Birds.

At an estimated 160 million years old, the Daohugou Beds are older than all the major bird-bearing fossil strata known, no definitive bird fossil may have been identified to date, but that is not surprising as at the time of the separation of the Aves from the Dinosauria, the birds closest relatives those non-avian Theropods, are going to look very similar.  What can be inferred from the evidence is that the ecosystem preserved as the Daohugou Biota represents the closest known to that point in geological time when the birds and the Dinosauria effectively split.

The Daohugou Biota

The Daohugou Biota is named after a small Chinese village close by to one of these six fossil locations.  What the international team of researchers have done is to link these locations together to prove that they represent a sequence of strata that was laid down at roughly the same point in deep time.  Radiometric dating has identified the age of the strata, but it is the presence of a signature fossil that has enabled the scientists to correlate the age of the separated deposits based on the fossils they contain.  The presence of the fossilised remains of a salamander (Chunerpeton tianyiensis) links these six locations together.  This amphibian’s fossils have effectively become a zonal fossil tying these six deposits together.

North-eastern China in the Middle Jurassic – Daohugou Biota

A rich and diverse Jurassic environment dominated by small mammals, pterosaurs and feathered theropods.

Picture credit: Julia Molnar

Biostratigraphy

The method of using the fossils of one or more species to identify the relative age of rock strata is called biostratigraphy.  C. tianyiensis has become a zonal fossil, a role more often than not played by invertebrates such as ammonites, graptolites and crinoids.

More importantly, although there are a number of families of vertebrates common to both the Daohugou Biota and the younger Jehol Biota, these two formations together represent an different ecosystems millions of years apart. The Daohugou Biota and the Jehol Biota are separate Lagerstätte assemblages that between them provide scientists with an unparalleled window into life in the Middle Jurassic and the Early Cretaceous of north-eastern China.

The Preserved Forequarters of a Specimen of C. tianyiensis (A Salamander)

Even the fine gills have been preserved.

Picture credit: Chinese Academy of Sciences/Journal of Vertebrate Palaeontology

Dating the Lioaning and Hebei Sediments

A spokes person from Everything Dinosaur commented:

“There has been confusion over the dating of the Lioaning and Hebei sediments, caused in part due to the large amount of fossil material that was made available to study which came from dubious sources such as local fossil collectors and dealers who rarely revealed exactly where the specimens came from, but now it seems that we have two “lost worlds” to study, one representing the Middle Jurassic and one representing younger sediments dating from the Cretaceous.  It is very likely that the Daohugou Beds will prove to be at least as biologically diverse as the fossil material that makes up the Jehol Biota, so we can expect to hear more announcements soon about further vertebrate discoveries.”

The Middle Jurassic deposits from these six Chinese locations have already provided fascinating glimpses into the weird and wonderful animals that lived in the forests and lakes that covered this part of the world 160 million years ago.  For instance, in 2008, Everything Dinosaur reported on the discovery of the bizarre fanged, feathered little dinosaur called Epidexipteryx.

Epidexipteryx

It has been suggested that this little dinosaur, which was no more than thirty centimetres in length, may have climbed trees.  For fans of the Pterosauria, the Daohugou Beds have provided a whole array of basal and derived forms of flying reptile such as the anurognathid pterosaur called Jeholopterus ningchenensis (note the confusing name from Jehol, although according to this new scientific paper, this pterosaur belongs to the Daohugou Biota and not the later Jehol Biota).

A number of rhamphorhynchid pterosaurs have been identified and sharing the same Jurassic skies was the recently discovered member of the Wukongopteridae pterosaur family called Darwinopterus modularis.

Composite Image of the Main Slab and Counter Slab of the Holotype Material of J. ningchenensis

Pterosaur fossil material.

Picture credit: Chinese Academy of Sciences/Journal of Vertebrate Palaeontology

To read more about the discovery of the flying reptile called Darwinopterus: New Transitional Pterosaur Fossil Discovery from North-eastern China.

Shedding Light on the Evolution of Mammals

These sediments are also shedding light on the evolution of mammals and what bizarre forms there were in the Middle Jurassic.  Fossils of a tree climbing mammal with a membrane of skin stretched between its limbs have been found. It has been suggested that this creature, called Volaticotherium, occupied the same niche in the arboreal ecosystem as today’s flying squirrel from Asia.  Living alongside the abundant salamanders was the peculiar Castorocauda, a mammal adapted to an aquatic lifestyle with a broad, flattened tail to help it swim.

These creatures may seem strange to us, but we suspect that lurking in the finely-grained sediments of the Daohugou Beds even more bizarre vertebrates are awaiting discovery.

To view replicas and models of prehistoric animals from the Daohugou Biota: PNSO Age of Dinosaurs Models.