Torvosaurus gurneyi

In March 2014, I published in a Plos One article on a new species of theropod dinosaur named Torvosaurus gurneyi. It was the first time I was naming a dinosaur and, to my surprise, the publication received an important media attention. Here are some information on this new species as well as my replies to the interviews I had with a couple of journalists.

Descriptive sheet

Systematic Paleontology

Dinosauria Owen, 1842 (Owen 1842)

Saurischia Seeley, 1887 (Seeley 1888)

Theropoda Marsh, 1881 (Marsh 1881)

Tetanurae Gauthier, 1986 (Gauthier 1986)

Megalosauroidea Fitzinger, 1843 (Fitzinger 1843)

Megalosauridae Fitzinger, 1843 (Fitzinger 1843)

Torvosaurus Galton & Jensen, 1979 (Galton and Jensen 1979)

Revised diagnosis—Megalosauroid theropod with very shallow maxillary fossa (i.e., maxillary fossa forming a poorly delimited concavity in the anterior corner of the lateral antorbital fossa; Carrano et al. 2012), protuberant ridge below the maxillary fossa, in the ventral part of the anterior corner of the lateral antorbital fossa, interdental wall making up one-half the medial surface of the maxillary body (modified from Britt 1991), expanded fossae in posterior dorsal and anterior caudal centra forming enlarged and deep pneumatic openings (Carrano et al. 2012), highly ossified puboischiadic plate (Carrano et al. 2012), and distal expansion of ischium with prominent lateral midline crest and oval outline in lateral view (Carrano et al. 2012).

Torvosaurus gurneyi Hendrickx & Mateus 2014 sp. nov. urn:lsid:zoobank.org:act:189C1060-7887-4837-9E30-870079E2B2B9.

Torvosaurus tanneri (Mateus et al. 2006).

Holotype—ML 1100, an incomplete left maxilla bearing one erupted tooth and one unerupted tooth, and the posterior portion of a proximal caudal vertebra.

Referred material—ALT-SHN.116, a portion of a right maxilla (Malafaia et al. 2008). ML 962, a mesialmost shed tooth (Hendrickx and Mateus 2014:fig. 9), FUB PB Ther 1, a lateral tooth, ML 430, an incomplete tibia (Mateus and Antunes 2000), ML 632, a partial femur (Mateus et al. 2006), and ML 1186, cranial and postcranial material of embryos (Araújo et al. 2013), are tentatively referred to T. gurneyi.

Type—Cliffs of Praia da Vermelha, Lourinhã, Portugal. Porto Novo-Amoreira Member, Lourinhã Formation, Upper Kimmeridgian, Upper Jurassic (Mateus et al. 2014).

Etymology—In honor of the paleoartist James Gurney, creator of the utopic world of Dinotopia.

Diagnosis—Megalosauroid theropod with maxillae bearing fewer than eleven teeth and possessing fused interdental plates with straight ventral margin forming an interdental wall nearly coincidental with the lateral wall of the maxillary body. Differs from Torvosaurus tanneri by fewer than eleven maxillary alveoli, the absence of interdental plates terminating ventrally by broad V-shaped points and falling short relative to the lateral wall, the absence of a protuberant ridge on the anterior part of the medial shelf, posterior to the anteromedial process, and the coincidental posterior extension of the dorsal and medial ridges of the anteromedial process.

Taphonomy—The specimen was found in beach eroded boulders that fell from the sea cliff. The bones did not show any signs of articulation, except the maxilla preserving the teeth in situ. The elements are not visibly compressed or deformed. The caudal centrum, directly associated with the maxilla and showing some Torvosaurus characters, has three patches of pyrite encrustations and is attached to charcoal. This suggests taphonomical or depositional anoxic conditions.

- Can you describe what this part of the world would have been like when the Torvosaurus gurneyi lived? Was it very populated? Wet? Forested? Etc.

CH: The Iberian peninsula, including what is now Portugal and Spain, was a large island isolated from North America by a proto-Atlantic Ocean. The current locality of Lourinhã was, by then, a river plain with a very diversified fauna dominated by dinosaurs. There were many herbivorous dinosaurs (sauropods, ankylosaurs, stegosaurs) and even more carnivorous dinosaurs (Torvosaurus, Allosaurus, Ceratosaurus, Lourinhanosaurus, etc.). Besides the dinosaurs were also present crocodiles, turtles, flying reptiles (pterosaurs), and small mammals. The fauna was rich, as much as the flora dominated by conifers and gingkos. It was a tropical environment with hot temperature of up to 35°C with seasonal changes: in summer it was warm and dry, in winter much more humid.

- So many of the fossil discoveries I hear about come from the US or China. I’m not familiar with this kind of work in Europe. Has this part of Portugal where you found this dinosaur yielded lots of dinosaur fossils? If so, what kind?

CH: Yes, this part of Portugal known as the Lourinhã Formation yielded a huge amount of dinosaurs, as many as the Morrison Formation of the same period of time (Late Jurassic, 150 million years ago). In Portugal, more than 10 different dinosaurs have been discovered already: Torvosaurus, Ceratosaurus, Allosaurus and Lourinhanosaurus for the theropods, Miragaia and Dacentrurus for the stegosaurus, Draconyx for the ornithopods, Dracopelta for the ankylosaurus, Lusotitan, Lourinhasaurus and Dinheirosaurus for the sauropods.

- How come that recently described dinosaur embryos from Portugal are also ascribed to the new species of Torvosaurus?

Yes, there is a paper on these embryos described by my colleagues and I last year: http://www.nature.com/srep/2013/130530/srep01924/full/srep01924.html These embryos were assigned to the genus Torvosaurus based on several anatomical features (see paper). Given the similar stratigraphic and paleogeographic distributions of Torvosaurus gurneyi and these Torvosaurus embryos, it is very likely that the embryos belong to that species as well. However, they are, for now, tentatively ascribed to T. gurneyi.

- What are your main findings (including when and where the fossils were found)?

CH: Our main finding is the discovery of a new species of very large carnivorous dinosaurs from the Late Jurassic of Portugal. This new species is named Torvosaurus gurneyi and is the largest terrestrial predator discovered in Europe hitherto. The fossils of this new dinosaur were found in the cliffs of Lourinhã, a small city situated 70 km North or Lisbon. The fossil material was discovered by the end of July 2003 by fossil amateur and collector Aart Walen.

- What is particularly remarkable about this dinosaur?

CH: Certainly its size. Jurassic theropods tend to be medium sized (i.e., 2-5 m in average) and large Jurassic theropods were only known in the latest stages of the Jurassic (Kimmeridgian – Tithonian) in North America (i.e., Allosaurus fragilis, Saurophaganax maximus, Torvosaurus tanneri). This new species of Torvosaurus, which is estimated to reach 10 meters long, indicates that large theropod dinosaurs also existed in the European archipelagos by the end of the Jurassic.

- It would not have been much fun for another dinosaur to run into this one, correct?

CH: With its large size and its blade shape teeth of more than 10 cm, Torvosaurus gurneyi was obviously a super-predator feeding on large preys like herbivorous dinosaurs. Although there is no evidence to support a predatory or a scavenger lifestyle for this theropod, some Torvosaurus must have attacked dinosaurs at least a few times in their lifetime. Therefore, it was indeed better not to cross the way of this large carnivorous dinosaur.

- How big was it – length, height, weight?

CH: Based on the size of the maxilla, a bone of the upper jaw, we estimated T. gurneyi to reach 10 meters long, and weight 4 to 5 tones. As for its height, the head was probably 3 meters above the floor. An incomplete femur from the Late Jurassic of Portugal and tentatively assigned to this species supports these estimations.

- This is not a new genus but a second species of Torvosaurus, correct?

CH: Exact, T. gurneyi is the second species of Torvosaurus, the first species is T. tanneri from North America.

- Where did the other Torvosaurus species live (and was the other one larger or smaller than this species)?

CH: In United States, in the states of Colorado, Utah and Wyoming hitherto.

- When was the first Torvosaurus species identified?

CH: The first species T. tanneri was coined in 1979 by Peter M. Galton and James A. Jensen.

- Does it date from roughly 150 million years ago?

CH: Yes, T. gurneyi lived in the Upper Kimmeridgian around 150 million years ago.

- Was it an exact contemporary of Allosaurus, and how does it compare in terms of size? Did their range overlap?

CH: Yes, Allosaurus and Torvosaurus were contemporary and cohabited in the same environment both in North America and Europe. In the Iberian peninsula, T. gurneyi was living besides many other theropods, including the species Allosaurus europaeus. Based on the fossil material that we have from the European Allosaurus, Torvosaurus was much larger. The only partial skull we have of Allosaurus europaeus is estimated to be 70-80 cm in length whereas this of Torvosaurus gurneyi is around 115 cm. Interestingly, some Allosaurus specimens from U.S. are as large, if not larger, than Torvosaurus tanneri. Based on the numerous theropod teeth collected in the Lourinhã Formation of Portugal, no Allosaurus were as large as Torvosaurus in Europe.

- Is this is largest known dinosaur predator ever in Europe?

CH: Yes, based on the maxilla, the teeth, of the holotype T. gurneyi and the femur tentatively referred to this species, it is the largest known predator in Europe, and therefore the largest known carnivorous dinosaur from that continent.

- How does it rate in terms of size compared to the largest theropods ever? (smaller, presumably, than Tyrannosaurus in North America, Carcharodontosaurus in Africa, and Giganotosaurus in South America in the Cretaceous)

CH: Although T. tanneri and T. gurneyicould reach 10 meters in length, other more recent theropods were even larger. In North America, Tyrannosaurus rex, from the Latest Cretaceous (Maastrichtian), is estimated to reach 12 meters long for a skull of up to 140 cm. Same for the carcharodontosaurids Carcharodontosaurus saharicus from the Upper Cretaceous (Cenomanian) of North Africa, with a skull estimated to reach 160 cm, for a length of 13-14 meter. Among terrestrial super-predators,the largest discovered so far is the carcharodontosaurid Giganotosaurus carolinii from the Upper Cretaceous (Cenomanian) of Argentina, with a skull estimated to reach 185 cm.Finally, the longest theropod seems to be Spinosaurus aegyptiacus, a fish-eating dinosaur from the Upper Cretaceous of North Africa (Cenomanian) that could have reached 16 to 18 meters in length, with a skull of 175 cm.

- Please describe the habitat in which it lived, and some of the other dinosaurs on which it may have preserved (large sauropods, ankylosaurs,stegosaurs, etc.). There were also early birds, pterosaurs and small mammals around too, correct?

OM: During the Late Jurassic of Portugal (about 150 Million years ago) this region was a river delta, somewhat similar to the delta of Mississippi river, with abundant fresh water and vegetation. Many other animals lived in the same area, including the potential prey, the plant-eater dinosaurs, such as the stegosaur Miragaia, sauropods Lusotitan, and ankylosaur Dracopelta, and many others. But also direct competitors, such as Allosaurus and Ceratosaurus. Many smaller animals lived in the shadows, like the flying pterosaurs, turtles, many small shrew-size mammals, primitive crocodiles, and rare birds.

- What was the largest previously known theropod from Europe? (see also below)

CH: The largest previously know theropod was Baryonyx walkeri from the Lower Cretaceous of England. This spinosaurid theropod was estimated to reach 10 meters by its discoverers but recent estimations gives to the animal a length of 8 meters for a weight of 2 tons. (see below for more information)

- What was the largest previously known theropod that lived in the same time and place as Torvosaurus gurneyi?

OM: The largest previously known theropod that lived in the same time and place as Torvosaurus gurneyi was Allosaurus europaeus, about 8 meters in length. Curiously both genera, Torvosaurus and Allosaurus, also lived in North America at that time.

- Was Torvosaurus gurneyi feathered?

CH: We do not know whether T. gurneyi had already proto-feathers (i.e., filamentous integuments) or not, as no fossil of integument was found associated with the fossils of this specimen. However, based on the recent discovery of a closely related dinosaur with filamentous integuments (Sciurumimus), T. gurneyi might have already been covered with proto-feathers.

- Was Europe linked to North America at the time?

OM: Not exactly at that time because there was a well formed sea, but some temporary land bridge must have existed a few million years before. Just in time to allow a common ancestor to both species of Torvosaurus to cross the sea, but with enough time to evolve into two different species.

CH: Although Europe and North America shared similar paleoenvironments, with similar latitudes, ecosystems and faunas, sedimentology and geology of the Iberian Peninsula in the Late Jurassic suggest that the proto-Atlantic was already well formed and that the Iberian Peninsula was a large island separated from North America. This explains the mechanisms of speciation that happened in the European Archipelagos in the Kimmeridgian – Tithonian.