| Taurovenator | |
|---|---|
 | |
| Reconstruction of the head ofTaurovenator | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Family: | †Carcharodontosauridae |
| Tribe: | †Giganotosaurini |
| Genus: | †Taurovenator Motta et al., 2016 |
| Type species | |
| †Taurovenator violantei Motta et al., 2016 | |
Taurovenator, fromLatintaurus, meaning "bull", andvenator, meaning "hunter", is an extinct genus of large, probablecarcharodontosauridtheropod dinosaurs that lived in what is now Argentina during theCenomanian age of theLate Cretaceous, around 95 to 93.9 million years ago. Initially only known from a singlepostorbital skull bone described from theHuincul Formation,Taurovenator violantei was named in 2016 by Argentine paleontologist Matias Motta and colleagues. Debate came about over the validity of the species, with some paleontologists arguing thatTaurovenator was synonymous with the earlier-named carcharodontosauridMapusaurus. However, the 2024 description of a well-preserved partial skull and skeleton referrable toTaurovenator aided in distinguishing the two taxa.
In 2005, a rightpostorbital of atheropod dinosaur was unearthed by Argentine paleontologistMatias Motta from a section ofsandstonestrata deriving from the lower member of theHuincul Formation, dating to theCenomanian stage of theLate Cretaceous (95-93.9 million years old).[1] The strata located on the Violante Farm, a farm located inRio Negro Province, Argentina. This fossil was found in the vicinity of themegaraptoranAoniraptor, severalabelisauroids, and a possibleunenlagiineparavian.[2] The fossils recovered were then transported to theMuseo Provincial "Carlos Ameghino", with the isolated postorbital deposited under catalogue number MPCA-Pv 803.[2] This postorbital remained undescribed until in 2016, when Matias Motta and colleagues described the postorbital as theholotype (name-bearing specimen) of a newgenus andspecies ofcarcharodontosaurid dinosaur,Taurovenator violantei.Taurovenator was then the second carcharodontosaurid described from the Huincul Formation, withMapusaurus named in 2006 based on several incomplete skeletons.[3][4] The generic nameTaurovenator means "bull hunter", derived from theLatin rootstaurus "bull" andvenor "hunter" whereas the specific name is in honor of Violante Farm where the postorbital was unearthed.[2][1]
Taurovenator went largely unnoticed due to its fragmentary nature,[5][1] with Coria et al. (2019) suggesting thatTaurovenator is synonymous withMapusaurus, considering both of its original autapomorphies as shared withMapusaurus and also pointing out that both taxa shared a curved lateral margin of thepalpebral.[6] Additionally, the authors considered that there was a high likelihood of them beingcoeval,[6] however,Taurovenator is actually from the lower unit of the Huincul Formation, whileMapusaurus is from the upper unit of the formation.[1] ResearcherMickey Mortimer also believed thatTaurovenator was synonymous withMapusaurus due to the lack of sufficient material and diagnostic traits for the genus.[7] In 2022, another carcharodontosaurid from the Huincul Formation,Meraxes, was named on the basis of a well-preserved skull and partial skeleton from the same strata asTaurovenator. In their description ofMeraxes, the authors stated thatTaurovenator lacks sufficient diagnostic characters and may be coeval withMeraxes.[5][1]
Notably in the same site on Violante Farm as theTaurovenator holotype, an associated skeleton (MPCA-Pv 803) including a partialskull and posterior (back portion)mandible, incompletecervical (neck vertebrae) series, fragments ofdorsal (back) vertebrae, severalribs, two partialforelimbs, afemur (thighbone), a partialpes (foot),gastralia, and acaudal vertebra was unearthed along with theTaurovenator holotype in 2005 but were regarded as belonging to an indeterminate carcharodontosaurid in the 2016 description ofTaurovenator. Additionally, the material of MPCA-Pv 803 had not been completely collected, prepared, or made available for study, delaying its description.[2][1] These fossils were also spread out over a sizeable area and intermingled with bones of an indeterminate sauropod. In 2024, this specimen was described and, despite not overlapping in material with the holotype, was referred toTaurovenator. This was done for several reasons: the holotype fits perfectly with MPCA-Pv 803 suggesting they may be from the same individual, the close proximity to the holotype (the specimen was found 800 metres (870 yd) away from the holotype's dig site, and the fossils are congruent in size. In an analysis of the strata from which the holotype was discovered, the 2024 study noted that the Huincul Formation is separated into two distinct sequences; a lower section of thin, multicolored sandstones and an upper section of thick conglomeratic sediments.Mapusaurus derives from the upper sequence of the formation, whereasMeraxes andTaurovenator are exclusive to the lower rock layers.Meraxes, however, was collected in strata close to the Candeleros-Huincul Formation boundary, whereasTaurovenator's specimens were found over 30 meters above the Candeleros-Huincul Formation limit. It is for these reasons that the three carcharodontosaurids found at Huincul were potentially not coeval, supporting the argument forTaurovenator's validity. Additionally, the holotype preserve features of theGiganotosaurini, further supporting its referral toTaurovenator. A new host of diagnostic traits were found on the bones of MPCA-Pv 803, properly demonstrating its distinctiveness fromMapusaurus andMeraxes.[1]
Taurovenator is a very large carcharodontosaurid. It had an estimated body mass of 5,728 kg (12,628 lb), 5.728 metric tons (6.314 short tons), based on a formula that utilizes the circumference of the femur to predict body mass. For reference, this is smaller thanGiganotosaurus 6,349 kilograms (13,997 lb), but larger thanMeraxes andMapusaurus, 4,263 kilograms (9,398 lb) and 4,343 kilograms (9,575 lb), respectively).[1][8] This putsTaurovenator among the largest theropod dinosaurs known and therefore one of the biggest terrestrial carnivores known to science, though still smaller than genera likeTyrannosaurus andSpinosaurus.[9][10][11][12]
The skull ofTaurovenator is known from the holotype postorbital in addition to the cranial and mandibular elements of MPCA-Pv 803 which include: bothjugals (cheekbones), leftquadrate (skull bone articulating with the lower jaw), leftpalatine (main palate bone), rightectopterygoid (smaller palate bone), bothsurangulars andangulars (back of lower jaw bones),prearticulars (rearmost lower jaw bone), leftarticular (lower jaw bone articulating with the skull), rightceratohyal (throat bone), and three isolatedteeth. The maximum length of the skull of MPCA-Pv 803 was estimated to be around 135 centimetres (4.43 ft) based on the more complete skulls of relatives likeMeraxes. Thepostorbital is strongly rugose and projected out like a horn, markedly different from the orbital bosses of other carcharodontosaurids. Both Motta et al., 2016 and Rolando et al., 2024 consider this a unique trait,[2][1] but its sister taxonMeraxes too has a postorbital that was described as laterally projecting out like a horn.[5] The 2024 description of MPCA-Pv 803 however argued that this horn-like projection is distinct from that ofMeraxes, with the projection measuring 3–4 centimetres (1.2–1.6 in) in height and 2–3 centimetres (0.79–1.18 in) in diameter. In addition, there is a deepfossa (depression in bone) and excavation on the ventral surface of the postorbital. Though the excavations are observable in the postorbitals ofMapusaurus, Meraxes, and other carcharodontosaurids, they all do not preserve the unique fossa found on theTaurovenator holotype.[1][2][3]
The jugal is long and sub-triangular in shape with a slightlyposteromedially (backwards) pointed postorbitalramus. Itslateral (exposed side) surface is rugose with a thick shelf, a condition similarly observed in South American carcharodontosaurids likeTyrannotitan andMeraxes but absent from the jugals of otherallosauroids. The anterior (front)process of the jugal is compressed and bears an ovularpneumaticforamen (pits in bone for air sac systems) on its articulating (contacting) surface with thelacrimal. The quadrate of MPCA-PV 803 is distinctly stout, triangular in lateral view, bearing a large, anteriorly projected pterygoid flange as in related genera. The pterygoid fossa is wide, subdivided by a crest, and lacks pneumaticity as in contemporary carcharodontosaurids of its time. In contrast the palatine ofTaurovenator is tetraradiate with an anteriorly expanded vomeropterygoidprocess (expansion), a short and sub-triangular pterygoid process, a narrow jugal process, and an elongated maxillary process. The ectopterygoid is C-shaped from dorsoventral (top and bottom) views with a pneumaticrecess on its medial surface, a trait in other tetanurans. A distinguishing feature ofTaurovenator's pterygoid is the thin, long jugal process which is longer than those ofMeraxes andGiganotosaurus. As for themandible, only the posterior portion is known fromTaurovenator. It preserves a robust and dorsoventrally (top-down) high morphology, akin to the mandibles ofAcrocanthosaurus, Tyrannosaurus, and othertyrannosauroids. Two teeth are preserved fromTaurovenator, both of which are large, around 4 centimetres (1.6 in) in length. The margins of these teeth are convex and straight, with chisel-likedenticles which number around 8.5 per 5 millimetres (0.20 in) at the mid-crown and 11 per 5 millimetres (0.20 in) at the base. Their blood grooves are well developed and theirenamel wrinkles are notably deep,[1] a distinct characteristic of carcharodontosaurid teeth.[13][14]
Distinctively, Taurovenator's neck vertebrae bore prominentneural spines with flange-like dorsal tips. As a result, the neural spines ofcervical vertebrae C3-C6 are "imbricated", ie interlocking with each other. The authors describing this morphology termed this unusual structure a "cervical complex", and likened them to overlapping roof tiles. A similar, though less extreme condition is also known in the C3-C5 of the more basal carcharodontosauridAcrocanthosaurus.[1][15] Available information ofGiganotosaurus andMapusaurus further suggests that this "cervical complex" is a uniquesynapomorphy of the group. The presence of the cervical complex would have likely restricted the range of movement of the cervical vertebrae. On the other hand, the skull ofTaurovenator and other carcharodontosaurids had a ball-shapedoccipital condyle similar to that seen in the skulls ofceratopsian dinosaurs. This could have allowed a large range of rotational movement between the skull and the first cervical vertebra. Furthermore, the cervical complex ofTaurovenator could have similar functional implications to those of thesyncervical vertebrae (ie fused C1-C3 vertebrae) of ceratopsians, strengthening the anterior region of the neck, and increasing the surface area for epaxial cervico-cranial muscles.[1]
Only remains of twodorsal vertebrae are known. One is composed of a centrum, but the other is composed of a very tall, 52 centimetres (20 in) high neural arch. This neural spine preserves strong laminae that form an "H"-shaped cross-section and a saddle shape at the top, traits found in the high-spinedAcrocanthosaurus. As for the appendicular skeleton, the forelimbs are nearly completely preserved, missing only the carpals and ungual phalanges.Taurovenator had proportionately some of the smallest arms of all knownallosauroids, being 65-68% of the length of the femur. The nearly completely preserved arms were reduced to a greater degree than even in other carcharodontosaurids, being proportionately smaller than that of taxa such asMeraxes, particularly where the forearm is concerned. Despite such limb reduction, the forearms were robust, and the digits had a great degree of flexibility. Nonetheless like other giganotosaurines, the forelimbs were likely incapable of a wide range of movement.[1] The left femur is known, with a preserved length of 113 centimetres (44 in) and an estimated complete length of 118 centimetres (46 in). The shaft of the femur is straightened with a weakfourth trochanter, a feature of many carcharodontosaurid femora.Taurovenator also shares withMeraxes an enlargedungual claw on the second toe, approximately 20% longer than the equivalentphalanx of the third toe and more laterally compressed.[1][2]
Motta et al. (2016) suggested thatTaurovenator occupied a derived position within Carcharodontosauridae, comparing it toGiganotosaurus,Carcharodontosaurus andMapusaurus in particular.[2] Coria et al. (2019) suggested thatTaurovenator is synonymous withMapusaurus, considering both of its original autapomorphies as shared withMapusaurus and also pointing out that both taxa shared a curved lateral margin of thepalpebral.[6] Additionally, the authors considered that there was a high likelihood of them beingcoeval,[6] however,Taurovenator is actually from the lower unit of the Huincul Formation, whileMapusaurus is from the upper unit of the formation.[1] Rolando et al. (2024) reaffirmedTaurovenator's validity, considering the autapomorphies preserved on the holotype as more strongly developed inTaurovenator than any other carcharodontosaurid, while also considering the supposedly diagnostic curved margin of the palpebral as a more widely distributed feature in Carcharodontosauridae.[1]
In order to test the systematics ofTaurovenator with the information supplemented by the new specimen, the study used the phylogenetic dataset used in the description ofMeraxes, with some additional data. The results of their phylogenetic analysis are shown in a cladogram below:[1][5]
In 2025, Cau and Paterna recoveredTaurovenator as anallosauroid outside Carcharodontosauridae.[16]
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Taurovenator was discovered in the Argentine Province ofNeuquén. It was found in the Huincul Formation, a rock formation bordering theRío Limay Subgroup, the latter of which is a subdivision of theNeuquén Group. Thisunit is located in theNeuquén Basin inPatagonia. The Huincul Formation is composed of yellowish and greenishsandstones of fine-to-medium grain, some of which aretuffaceous.[17] These deposits were laid down during the Upper Cretaceous, either in the middleCenomanian to earlyTuronian stages[2] or the early Turonian to lateSantonian.[18] The deposits represent thedrainage system of abraided river.[19]
Fossilised pollen indicates a wide variety of plants were present in the Huincul Formation. A study of the El Zampal section of the formation foundhornworts,liverworts,ferns,Selaginellales, possibleNoeggerathiales,gymnosperms (includinggnetophytes andconifers), andangiosperms (flowering plants), in addition to several pollen grains of unknown affinities.[20] The Huincul Formation is among the richest Patagonian vertebrate associations, preserving fish includingdipnoans andgar,chelid turtles,squamates,sphenodonts,neosuchiancrocodilians, and a wide variety of dinosaurs.[2][21] Vertebrates are most commonly found in the lower, and therefore older, part of the formation.[22]
In addition toTaurovenator, the theropods of the Huincul Formation are represented by the other giant carcharodontosauridsMeraxes andMapusaurus,abelisaurids includingSkorpiovenator,[23]Ilokelesia, andTralkasaurus,[24]noasaurids such asHuinculsaurus,[25]paravians such asOveroraptor,[26] and other theropods such asAoniraptor andGualicho[27] have also been discovered there.[2] Severaliguanodonts are also present in the Huincul Formation.[17] Thesauropods of the Huincul Formation are represented by thetitanosaursArgentinosaurus andChoconsaurus,[28] and severalrebbachisaurids includingCathartesaura,[29]Limaysaurus,[30][31] and some unnamed species.[22]
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