Torvosaurus () is a genus of large megalosaurine theropod dinosaur that lived approximately 165 to 146.5 million years ago during the Callovian to Tithonian ages of the late Middle and Late Jurassic period in what is now Colorado, Portugal, Germany, and possibly England, Spain, Tanzania, and Uruguay. It contains two currently recognized species, Torvosaurus tanneri and Torvosaurus gurneyi, plus a third unnamed species from Germany.
In 1979, the type species Torvosaurus tanneri was named. Measuring around long and weighing approximately , T. tanneri was among the largest terrestrial carnivores in North America during the Late Jurassic. Specimens of Torvosaurus gurneyi were measured up to in length and in body mass. Both species are regarded as being similar in size to each other. Based on bone morphology, Torvosaurus is thought to have had very powerful short arms.
Discovery
Fossilized remains of Torvosaurus have been found in North America, Portugal, Germany, and possibly in England, Spain, Tanzania, and Uruguay. The first discovered remains referable to Torvosaurus were discovered in 1899 by Elmer Riggs in the "Freeze-out Hills" of southeastern Wyoming, northwest of Medicine Bow. The material consisted of part of the left foot and right hand and they were taken to the Field Museum of Natural History in Chicago, where they were stored until being re-discovered around 2010. The specimen was assigned to Torvosaurus tanneri after being described in 2014.
More remains of a large theropod that is now believed to have been Torvosaurus were discovered in the Tendaguru Formation of Tanzania and was named "Megalosaurus" ingens by Werner Janensch in 1920, based on the specimen MB R 1050, a tooth from German East Africa (now Tanzania). It was eventually reclassified as a probable member of Carcharodontosauridae before being reclassified as a probable member of the Torvosaurus genus in 2020. Although it was only referred to as Torvosaurus sp., one commentator has noted it could potentially be called Torvosaurus ingens. Soto et al. (2020) described teeth of a member of the genus Torvosaurus from the Tacuarembó Formation of Uruguay. The authors noted that some of the specimens of "Megalosaurus" ingens figured by Werner Janensch share the features of the Uruguayan material and stated that the materials from Tanzania and Uruguay may represent the same taxon, due to geographical proximity, but ultimately concluded that, based on only teeth, they do not share any derived characteristics to distinguish them from the described species of the genus, T. tanneri and T. gurneyi.Tacuarembó Formation at Fossilworks.org However, Rauhut et al. (2020) consider the teeth to be undiagnostic, being coherent in size and shape with a variety of other theropods (including carcharodontosaurids), thus considering their attribution to the genus to be problematic.
In 1971, Vivian Jones of Delta, Colorado, in the Calico Gulch Quarry in Moffat County, discovered a single gigantic thumb claw of a theropod. This was shown to James Alvin Jensen, a collector who was working for Brigham Young University. In an effort to discover comparable fossils, Vivian's husband Daniel Eddie Jones directed Jensen to the Dry Mesa Quarry, where abundant gigantic theropod bones, together with Supersaurus remains, proved present in rocks of the Morrison Formation. From 1972 onward, the site was excavated by Jensen and Kenneth Stadtman. The type species Torvosaurus tanneri was named and described in 1979 by Peter Malcolm Galton and Jensen. The genus name Torvosaurus derives from the Latin word torvus, meaning "savage", and the Greek word sauros (σαυρος), meaning "lizard". The specific name tanneri comes from the, first counselor in the First Presidency of the Church of Jesus Christ of Latter-day Saints, Nathan Eldon Tanner.
In 1985, Jensen could report a considerable amount of additional material, among it being the first skull elements.Jensen, J.A., 1985, "Uncompahgre dinosaur fauna: A preliminary report", Great Basin Naturalist, 45: 710–720 The fossils from Colorado were further described by Brooks Britt in 1991. The holotype, BYU 2002, originally consisted of upper and lower arm bones. The paratypes included some back bones, hip bones, and hand bones. When the material described in 1985 is added, the main missing elements are the shoulder girdle and the thighbone. The original thumb claw, specimen BYUVP 2020, was only provisionally referred, as it had been found in a site away from the Dry Mesa Quarry. The holotype and paratypes represented at least three individuals, these being two adults and a juvenile. In 1991, Britt concluded that there was no proof that the front limbs of the holotype were associated and chose the left humerus as the lectotype. Several single bones and teeth found in other American sites have been referred to Torvosaurus.
In 1992, fossils of a large theropod found at Como Bluff in Wyoming contained skull, shoulder girdle, pelvic, and rib elements. Robert T. Bakker and colleagues named the new species Edmarka rex based on these specimens, CPS 1001-1006 and CPS 1010, and suggested that it would rival Tyrannosaurus in size. In an unpublished 1996 manuscript, Siegwarth et al. (1996) re-examined the specimen TATE 0012 (then accessioned as CPS 1003) originally assigned to Edmarka rex by Bakker et al. (1992) from the same site, and stated that they initially considered to name this specimen "Brontoraptor", but decided to wait for more complete specimens to name this taxon officially, which renders this name a nomen nudum (informal name).Siegwarth, J.D.; Linbeck, R.A.; Redman, P.D.; Southwell, B.; Bakker, R.T. (1996). Giant carnivorous dinosaurs of the family Megalosauridae. pp. 1–79 Most researchers now regard both Edmarka rex and "Brontoraptor" as junior synonyms of Torvosaurus tanneri. In 2014, Sebastian Dalman suggested that while Edmarka rex and "Brontoraptor" are most likely junior synonyms of T. tanneri, the original incomplete specimens assigned to these taxa require re-examination as they lack detailed osteological descriptions to confirm or dispute this supposed synonymy.
In 2012, a still undescribed, 55% complete specimen was discovered in Colorado in the Skull Creek Quarry, which is an exposure of the Morrison Formation. The specimen, nicknamed "Elvis", included the pelvic, spine, and hind limb bones, a complete, associated backbone, as well as cranial elements. It is the most complete specimen of Torvosaurus found to date. A mounted skeleton of the specimen, with missing parts reconstructed with casts from other Torvosaurus specimens, is currently on display in the Museum of Natural History & Science in Cincinnati.
In 2000, material from Portugal was referred to a Torvosaurus sp. by Octávio Mateus and Miguel Telles Antunes.Mateus, O., & Antunes, M. T. (2000). Torvosaurus sp.(Dinosauria: Theropoda) in the late Jurassic of Portugal. In I Congresso Ibérico de Paleontologia/XVI Jornadas de la Sociedad Española de Paleontología (pp. 115–117) In 2006, fossils from the Portuguese Lourinhã Formation were referred to Torvosaurus tanneri. In 2012, however, Matthew Carrano and colleagues concluded that this material could not be more precisely determined than a Torvosaurus sp. In 2013 and 2014, eggs with and without embryos were reported from Portugal and referred to Torvosaurus. The species from Portugal was named T. gurneyi in honor of James Gurney in 2014, the creator of the Dinotopia series of books. It is the largest named theropod known from Europe, although an isolated anterior caudal vertebra from the Vega Formation in Spain, which may belong to Torvosaurus or a closely related taxon, is about 15% larger than the one found on T. gurneyi. One of the describers of T.gurneyi argued the giant vertebrae from the Vega Formation likely does belong to T.gurneyi. It was the morphological distinctiveness of the holotype maxilla ML1100 that led to the naming of the Portuguese species. In 2017, a set of Portuguese cranial material assigned to Torvosaurus was described, including a specimen interpreted as belonging to the same individual as the holotype of Torvosaurus gurneyi.
In 2020, Soto and colleagues described FC-DPV 2971, a tooth from Uruguay, as belonging to a new unnamed species of Torvosaurus. They also assigned Megalosaurus/Ceratosaurus ingens (specimen MB R 1050) from Tanzania to Torvosaurus. Also in 2020, a fragmentary maxilla referable to Torvosaurus was described from the middle Callovian Ornatenton Formation of Germany. This is the record of the genus and suggests that megalosaurines originated in Europe, or at least that Europe was a biogeographical turntable for them from the Middle to the early Late Jurassic. Other possible Torvosaurus instances in Europe include fragmentary remains from the Kimmeridge Clay of England that possibly belong to the genus. These consist of a tibia (OUMNH J.29886) and a maxilla fragment that were collected separately from each other. In 2016 teeth regarded as likely coming from Torvosaurus were described from the Kimmeridgian of Germany.
Description
Torvosaurus was a very large and robust predatory dinosaur. Galton and Jensen initially estimated the body length of T. tanneri at in their 1979 description of the taxon. Subsequent studies have estimated that adults reached in length, and weighed up to . Edmarka & "Brontoraptor" are large animals and are usually regarded as synonyms of T. tanneri. However, some researchers suggest that Edmarka rex and "Brontoraptor" may have been distinct from Torvosaurus. T. gurneyi is estimated to have measured in length and weighed .T. gurneyi is estimated to have a hip height of . The unnamed species from Germany is estimated to have been similar in size to T. tanneri.
Among the differentiating features originally recognized between T. gurneyi and T. tanneri are the number of teeth, alongside the size and shape of the mouth. While the upper jaw of T. tanneri has more than 11 teeth, that of T. gurneyi has less. However, later examination of a new right maxilla, probably belonging to the same individual as the holotype of T. gurneyi, has determined that, while the two species can be distinguished based on the morphology of the maxillary medial wall and interdental plates, the supposedly lower number of maxillary teeth in the Portuguese form may be an artifact of preservation, since it is not possible to know the exact number of teeth in the complete maxilla at the moment.
The material from Germany is further distinguished by the other two species by a temporal difference of c. 10 Ma and a few morphological differences which indicate that it was the third species outside a sister taxon relationship between T. tanneri and T. gurneyi. The material is only 10% smaller than the maxilla of T. tanneri, although the ontogenetic stage of the specimen is unknown. This indicates that derived megalosaurines were already among the largest terrestrial predators of the late Middle Jurassic, with only a moderate increase in size in the genus by the Late Jurassic. Torvosaurus had a maxillary crown height to skull length ratio of at least 9.