Tratayenia

Last updated

Tratayenia
Temporal range: Late Cretaceous, 86–83  Ma
O
S
D
C
P
T
J
K
Pg
N
Tratayenia.jpg
Life restoration
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: Megaraptora
Family: Megaraptoridae
Genus: Tratayenia
Porfiri et al., 2018
Type species
Tratayenia rosalesi
Porfiri et al., 2018

Tratayenia is an extinct genus of megaraptoran theropod dinosaurs known from remains found in the Santonian-age Bajo de la Carpa Formation of Argentina. [1] The type and only species, Tratayenia rosalesi, was described in March 2018. [2]

Contents

Tratayenia can be distinguished from other megaraptorans on the basis of three autapomorphies (unique derived features) of the front portion of each dorsal vertebra, as well as a single autapomorphy of the sacrum. Tratayenia is one of the youngest known genera of megaraptorans, having lived only about 83 million years ago.

Discovery and naming

The holotype consists of a well-preserved partial skeleton, MUCPv 1162, which includes several articulated portions of the backbone. One portion of the skeleton is a string of five dorsal vertebrae, likely the seventh to eleventh dorsals. The largest articulated portion of the skeleton is a string of vertebrae including the last two dorsals as well as the five sacrals and much of the right ilium. Other preserved bones include two partial dorsal ribs and fragments of the pubis and ischium. [1]

This skeleton was first discovered in 2006 at a Bajo de la Carpa Formation fossil site by Universidad Nacional del Comahue technician Diego Rosales. Shortly thereafter it was excavated by UNC paleontologist Juan D. Porfifi. Porfiri and his colleagues published a preliminary report on the new dinosaur in a 2008 abstract, and suggested that it may have been a relative of Carcharodontosauridae. [3] In 2018, the new taxon was described with the generic name Tratayenia, named after Tratayén, the fossil site at which it was excavated. The specific name Tratayenia rosalesi honors Diego Rosales. [1]

Description

Tratayenia was a medium-sized megaraptoran, growing up to 8 metres (26 ft) long. It was closely related to genera such as Megaraptor , Australovenator , and Murusraptor . Like most other megaraptorans, it probably had large claws on its hands for use in hunting prey. Analysis of the Baja de la Carpa indicates that Tratayenia may have been geologically one of the youngest megaraptorans yet discovered. Tratayenia is also the largest-bodied carnivorous animal named from the Bajo de la Carpa Formation, reinforcing the hypothesis that megaraptorids were apex predators in southern South America from the Turonian through the Santonian or early Campanian, following the extinction of carcharodontosaurids. [1] [2]

Dorsal vertebrae

The dorsal vertebrae were tall and narrow, with large pits known as pleurocoels on the side of their centra (spool-shaped main portion). These features are common in the vertebrae of large carnivorous theropods. Some of the vertebrae had fragments of bone in the pleurocoels, which were likely remnants of thin bony walls known as septa which divided the pits. Septa are also known in other megaraptorans and carcharodontosaurids. The neural arches of the vertebrae are taller and narrower in Tratayenia than in most other theropods. The tubular transverse processes (rib facets) project upwards and to the side. A large and deep excavation is located directly below each transverse process, bounded from the front and rear by thin laminae (ridges). The front edge is formed by the paradiapophyseal lamina and the rear edge is formed by the posterior centrodiapophyseal lamina. These features are also known in the megaraptoran Murusraptor. [1]

The prezygapophyses (front vertebral joint plates) are rectangular when see from the side, with the front and lower edges converging at nearly a right angle. This is an autapomorphy (unique adaptation) of Tratayenia. A ridge known as a prezygodiapophyseal lamina connects the prezygapophyses to the transverse processes. Another autapomorphy of Tratayenia is that the prezygodiapophyseal lamina is parallel to the paradiapophyseal lamina. Other theropods either have a weakly developed (or absent) paradiapophyseal lamina, or one which is angled relative to the prezygodiapophyseal lamina. The front edge of each vertebra has a third autapomorphy, related to two pairs of laminae (four total) connecting the prezygapophyses to the neural spines. At the base of the neural spines, the two laminae comprising each pair are very close together. But as the laminae get closer to the prezygapophyses, they diverge into a shape akin to an inverted Y. There are two of these inverted Y-like structures visible from the front, for both the left and right sides of a vertebra. [1]

The postzygapophyses (rear vertebral joint plates) are more typical in shape, and the rear edge of each vertebra has a small, blade-like hyposphene which splits into three ridges from below. The neural spines are tall and rectangular when seen from the side, and uniformly thin when seen from the front. Most are completely vertically, but one of the dorsal vertebrae preserved near the hip slightly inclines forward as in various allosauroids. Preserved rib fragments are curved and hollow. They connected to the vertebrae by means of two distinct condyles, separated by a large opening which may have been continuous with the inner cavity. [1]

Sacrum and hip

Tratayenia has five sacral (hip) vertebrae, as is the norm for theropods. They are very similar to the dorsal vertebrae in various aspects, such as the presence of large pleurocoels, tall and narrow centra, and laminae-bound excavations below the transverse processes. However, they only have a single autapomorphy: the anteroposterior (front-to-back) width of the neural spine increases drastically in the second to fifth sacral vertebrae compared to the first vertebra. In fact, the fifth sacral's neural spine is twice as long anteroposteriorly than that of the first. This trait has also been observed in Tyrannosaurus and an unnamed megaraptoran sacrum (SNMS 58023) from the Romualdo Member of the Santana Formation in Brazil, [4] so its status as an autapomorphy of Tratayenia is not concrete. Some of the sacral vertebrae have neural spines which are fused together, and the last three curve backwards. The fourth sacral has a shape similar to those of the Santana Formation sacrum. [1]

The ilium (upper blade of the hip) was heavily pneumatized, meaning that it was filled with air pockets. Pneumatization of the ilium is most common in megaraptorans among theropods, as seen in taxa such as Aerosteon and Murusraptor. The outer surface of the ilium is perforated by several pneumatic pores, similar to that of Aerosteon, but the upper edge of the bone is straight, in contrast with the curved ilium of Aerosteon. A bone identified as the pubic boot (expanded tip of the pubis) has been found in the holotype, as well as fragments of the ischium, which has the form of a long, thin shaft covered in grooves. [1]

Classification

Megaraptorans have very controversial relations to other theropods. The first mainstream hypothesis is that they are carnosaurs, distantly related to Allosaurus and more closely related to Neovenator and carcharodontosaurids. The second popular hypothesis considers them to be basal tyrannosauroids, part of the coelurosaur lineage which includes the crested proceratosaurids as well as the famous tyrannosaurids such as Tyrannosaurus . [5] A third hypothesis also considers them to be coelurosaurs, but outside Tyrannosauroidea and basal to practically all other groups of Coelurosauria. Porfiri et al.'s description of Tratayenia prefers this third hypothesis. [1]

The cladogram below follows the strict consensus (average result) of the 12 most parsimonious trees (the simplest evolutionary paths, in terms of the total amount of sampled features evolved or lost between sampled taxa) found by Porfiri et al. (2018)'s phylogenetic analysis. [1] Although the results are different, the methodology analysis was practically identical to that of Apesteguia et al. (2016), only differing in the fact that it incorporated Tratayenia and Murusraptor, two megaraptorans not sampled in the analysis of Apesteguia et al. [5]

Avetheropoda

Eocarcharia Eocarcharia, improved.png

Neovenator Neovenator.png

Concavenator Concavenator corcovatus by Daniel Vidal 2012.png

Acrocanthosaurus Acrocanthosaurus restoration.jpg

Allosaurus Allosaurus Revised.jpg

Sinraptor

Monolophosaurus Monolophosaurus jiangi jmallon.jpg

Shaochilong Shaochilong.jpg

Carcharodontosaurus Carcharodontosaurus.png

Tyrannotitan

Mapusaurus Mapusaurus Roseae restoration.png

Giganotosaurus Giganotos Db.jpg

Coelurosauria

Gualicho Gualicho shinyae restoration.jpg

Chilantaisaurus Chilantaisaurus.jpg

Megaraptora

Fukuiraptor

Megaraptoridae

Murusraptor Murusraptor NT small.jpg

Tratayenia

Megaraptor

Aerosteon

Australovenator Australovenator reconstruction.jpg

Orkoraptor Orkoraptor drawing.jpg

Tyrannoraptora Stokesosaurus by Tom Parker.png

Paleoecology

Tratayenia lived in the Bajo de la Carpa Formation alongside many lizards and turtles, the snake species Dinilysia patagonica , many birds such as Patagopteryx deferrariisi , a diverse amount of crocodylomorphs and many dinosaurs such as Viavenator exxoni and Traukutitan eocaudata .

See also

Related Research Articles

<i>Chilantaisaurus</i> Theropod dinosaur genus from the Late Cretaceous period

Chilantaisaurus is a genus of large theropod dinosaur, possibly a neovenatorid or basal coelurosaur, from the Late Cretaceous Ulansuhai Formation of China. The type species, C. tashuikouensis, was described by Hu in 1964. Chilantaisaurus was a large theropod, estimated as weighing between 2.5 metric tons and 4 metric tons. In 2010, Brusatte et al. estimated it to weigh 6,000 kilograms (13,000 lb), based on femur length measurements. It is estimated to be around 11 m (36 ft) to 13 m (43 ft) long.

<i>Euhelopus</i> Extinct genus of dinosaurs

Euhelopus is a genus of sauropod dinosaur that lived between 145 and 133 million years ago during the Berriasian and Valanginian stages of the Early Cretaceous in what is now Shandong Province in China. It was a large quadrupedal herbivore. Unlike most other sauropods, Euhelopus had longer forelegs than hind legs. This discovery was paleontologically significant because it represented the first dinosaur scientifically investigated from China: seen in 1913, rediscovered in 1922, and excavated in 1923 and studied by T'an during the same year. Unlike most sauropod specimens, it has a relatively complete skull.

<i>Ekrixinatosaurus</i> Extinct genus of reptiles

Ekrixinatosaurus is a genus of abelisaurid theropod which lived approximately 100 to 97 million years ago during the Late Cretaceous period. Its fossils have been found in Argentina. Only one species is currently recognized, Ekrixinatosaurus novasi, from which the specific name honors of Dr. Fernando Novas for his contributions to the study of abelisaurid theropods.

<i>Epachthosaurus</i> Extinct genus of dinosaurs

Epachthosaurus was a genus of titanosaurian sauropod dinosaur from the Late Cretaceous. It was a basal titanosaur. Its fossils have been found in Central and Northern Patagonia in South America.

<i>Klamelisaurus</i> Extinct genus of dinosaurs

Klamelisaurus is a genus of herbivorous sauropod dinosaur from the Middle Jurassic Shishugou Formation of China. The type species is Klamelisaurus gobiensis, which was named by Zhao Xijin in 1993, based on a partial skeleton discovered in 1982 near the abandoned town of Jiangjunmiao. Zhao described Klamelisaurus as the only member of a new subfamily, Klamelisaurinae, among the now-defunct primitive sauropod order Bothrosauropodoidea. Since Zhao's description, Klamelisaurus received limited attention from researchers until Andrew Moore and colleagues redescribed it in 2020.

The Bajo de la Carpa Formation is a geologic formation of the Neuquén Basin that crops out in northern Patagonia, in the provinces of Río Negro and Neuquén, Argentina. It is the oldest of two formations belonging to the Río Colorado Subgroup within the Neuquén Group. Formerly, that subgroup was treated as a formation, and the Bajo de la Carpa Formation was known as the Bajo de la Carpa Member.

<i>Puertasaurus</i> Extinct genus of dinosaurs

Puertasaurus is a genus of sauropod dinosaur that lived in South America during the Late Cretaceous Period. It is known from a single specimen recovered from sedimentary rocks of the Cerro Fortaleza Formation in southwestern Patagonia, Argentina, which probably is Campanian or Maastrichtian in age. The only species is Puertasaurus reuili. Described by the paleontologist Fernando Novas and colleagues in 2005, it was named in honor of Pablo Puerta and Santiago Reuil, who discovered and prepared the specimen. It consists of four well-preserved vertebrae, including one cervical, one dorsal, and two caudal vertebrae. Puertasaurus is a member of Titanosauria, the dominant group of sauropods during the Cretaceous.

<i>Achillesaurus</i> Extinct genus of dinosaurs

Achillesaurus is a genus of alvarezsaurid theropod dinosaur from the Santonian-age Upper Cretaceous Bajo de la Carpa Formation of Rio Negro, Argentina. It was named in reference to Achilles' heel, because diagnostic features are found there for these animals. The genus was a relatively large, basal alvarezsaurid, and a contemporary of Alvarezsaurus. Achillesaurus is based on MACN-PV-RN 1116, a partial skeleton including a sacral vertebra, four tail vertebrae, part of the left thighbone, shin and foot, and the left ilium. Agustín Martinelli and Ezequiel Vera, who described the specimen, performed a phylogenetic analysis and found their new genus to be an alvarezsaurid with an unresolved relationship to Alvarezsaurus and more derived alvarezsaurids. Makovicky, Apesteguía & Gianechini (2012) argued that Achillesaurus might actually be a junior synonym of Alvarezsaurus which, according to the authors, "is known from the same formation and from which it [i.e. Achillesaurus] differs trivially."

<i>Aerosteon</i> Extinct genus of dinosaurs

Aerosteon is a genus of megaraptoran dinosaur from the Late Cretaceous period of Argentina. Its remains were discovered in 1996 in the Anacleto Formation, which is from the late Campanian. The type and only known species is A. riocoloradense. Its specific name indicates that its remains were found 1 km north of the Río Colorado, in Mendoza Province, Argentina.

Bahariasauridae Probable family of averostran theropods

Bahariasauridae is a potential family of averostran theropods that might include a handful of African and South American genera, such as Aoniraptor, Bahariasaurus, Deltadromeus, and Gualicho. The placement of these theropods is controversial, with some studies placing them as basal ceratosaurs possibly related to Noasauridae, others classifying them as megaraptorans, basal neovenatorids, or basal coelurosaurs. There is also a possibility the group might not be monophyletic, as a monograph on the vertebrate diversity in the Kem Kem Beds published in 2020 found Bahariasaurus to be nomen dubium. In the same paper Deltadromeus is classified as an abelisaurid.

Megaraptora Extinct clade of dinosaurs

Megaraptora is a clade of carnivorous theropod dinosaurs with controversial relations to other theropods. Its derived members, the Megaraptoridae are noted for their elongated hand claws and proportionally large arms, which are usually reduced in size in other large theropods.

<i>Ichthyovenator</i> Genus of dinosaur

Ichthyovenator is a genus of spinosaurid dinosaur that lived in what is now Laos, sometime between 125 and 113 million years ago, during the Aptian stage of the Early Cretaceous period. It is known from fossils collected from the Grès supérieurs Formation of the Savannakhet Basin, the first of which were found in 2010, consisting of a partial skeleton without the skull or limbs. This specimen became the holotype of the new genus and species Ichthyovenator laosensis, and was described by palaeontologist Ronan Allain and colleagues in 2012. The generic name, meaning "fish hunter", refers to its assumed piscivorous lifestyle, while the specific name alludes to the country of Laos. In 2014, it was announced that more remains from the dig site had been recovered; these fossils included teeth, more vertebrae (backbones) and a pubic bone from the same individual.

<i>Siats</i> Extinct genus of theropod dinosaur

Siats /see-ats/ is an extinct genus of large neovenatorid dinosaur known from the Late Cretaceous Cedar Mountain Formation of Utah, United States. It contains a single species, Siats meekerorum. S. meekerorum could be the first neovenatorid discovered in North America and the geologically youngest allosauroid yet discovered from the continent. It was initially classified as a megaraptoran, a clade of large theropods with very controversial relationships. This group may be examples of early tyrannosauroids, neovenatorid allosauroids, or basal coelurosaurs.

Datanglong is an extinct genus of carcharodontosaurian theropod belonging to the Tetanurae. It existed during the Early Cretaceous (Barremian-Albian) in what is now southeastern China.

<i>Morelladon</i> Extinct genus of dinosaurs

Morelladon is an extinct genus of herbivorous styracosternan ornithopod dinosaur. It lived during the Early Cretaceous of Spain, around 130 million years ago.

Gualicho is a genus of theropod dinosaur. The type species is Gualicho shinyae. It lived in what is now northern Patagonia, on what was then a South American island continent split off from the supercontinent Gondwana. The fossils were found in the Huincul Formation, dating to the late Cenomanian-early Turonian age of the upper Cretaceous Period, around 93 million years ago.

<i>Murusraptor</i> Extinct genus of dinosaurs

Murusraptor is a genus of carnivorous megaraptoran theropod dinosaur from the Sierra Barrosa Formation, part of the Neuquén Group of Patagonia, in Argentina, South America. It is known from a single specimen that consists of a partial skull, ribs, partial pelvis, leg and other assorted skeletal elements.

Lohuecotitan is an extinct genus of titanosaurian sauropod dinosaur which lived during the Late Cretaceous in Spain. The only species known in the genus is Lohuecotitan pandafilandi, described and named in 2016.

<i>Austroposeidon</i> Extinct genus of dinosaurs

Austroposeidon is an extinct genus of titanosaurian sauropod dinosaur from the Late Cretaceous Presidente Prudente Formation of Brazil. It contains one species, Austroposeidon magnificus.

Tralkasaurus is a genus of abelisaurid dinosaur from the Huincul Formation from Río Negro Province in Argentina. The type and only species is Tralkasaurus cuyi, named in 2020 by Mauricio Cerroni and colleagues based on an incomplete skeleton. A medium-sized abelisaurid, Tralkasaurus exhibits a conflicting blend of characteristics found among the early-diverging abelisauroids with others that characterize the highly specialized clade Brachyrostra, and thus its position within the clade is poorly-resolved.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 Porfiri, Juan D; Juárez Valieri, Rubén D; Santos, Domenica D.D; Lamanna, Matthew C (2018). "A new megaraptoran theropod dinosaur from the Upper Cretaceous Bajo de la Carpa Formation of northwestern Patagonia". Cretaceous Research. 89: 302–319. doi:10.1016/j.cretres.2018.03.014.
  2. 1 2 Fonseca, Lurdes (28 March 2018). "Just out | A new megaraptoran theropod dinosaur from the Upper Cretaceous Bajo de la Carpa Formation of northwestern Patagonia @ Cretaceous Research". Paleowire.
  3. Porfiri, Juan D.; Calvo, Jorge O.; Juarez Valieri, Ruben D.; Santos, Dominica D. (2008). "A new large theropod dinosaur from the Bajo de La Carpa Formation (Late Cretaceous) of Neuquén, Patagonia". Ill Congreso Latinoamericano de Paleontologia de Vertebrados.
  4. Aranciaga Rolando, Alexis M.; Brissón Egli, Federico; Sales, Marcos A.F.; Martinelli, Agustín G.; Canale, Juan I.; Ezcurra, Martín D. (2018). "A supposed Gondwanan oviraptorosaur from the Albian of Brazil represents the oldest South American megaraptoran". Cretaceous Research. 84: 107–119. doi:10.1016/j.cretres.2017.10.019. ISSN   0195-6671.
  5. 1 2 Apesteguía, Sebastián; Smith, Nathan D.; Juárez Valieri, Rubén; Makovicky, Peter J. (2016-07-13). "An Unusual New Theropod with a Didactyl Manus from the Upper Cretaceous of Patagonia, Argentina". PLOS ONE. 11 (7): e0157793. doi: 10.1371/journal.pone.0157793 . PMC   4943716 . PMID   27410683.