Maip

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Maip
Temporal range: Late Cretaceous, Maastrichtian
Maip macrothorax.png
Known material (A), reconstruction of the thoracic cavity at level of sixth dorsal vertebra (B), and interpretative drawing of the excavation (C)
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade:† Megaraptora
Family:† Megaraptoridae
Genus:† Maip
Rolando et al., 2022
Species:
†M. macrothorax
Binomial name
†Maip macrothorax
Rolando et al., 2022

Maip is a genus of large megaraptorid theropod dinosaur from the Late Cretaceous (Maastrichtian) Chorrillo Formation of Santa Cruz, Argentina. The genus contains a single species, M. macrothorax, known from an incomplete, disarticulated skeleton. Maip may represent the largest megaraptorid known from South America, and possibly the world. [1]

Discovery and naming

Holotype bones Maip holotype.jpg
Holotype bones

The Maip holotype specimen, MPM 21545, was discovered by Alexis Rolando on the La Anita Farm, 30 kilometres (19 mi) west of El Calafate, Santa Cruz province, Argentina, in 2019. The specimen was found disarticulated but in association over an area of 5 by 3 square metres (54 sq ft × 32 sq ft). The known fossil material consists of the axis, several dorsal and caudal vertebrae, cervical and dorsal ribs, gastralia, a left coracoid, fragmentary scapula, partial right pubis, and partial metatarsal. Some of these bones were described in 2019 by Novas et al. [2] The holotype specimen includes some bones previously unknown in other megaraptorids. Although fragmentary, it represents one of the most complete megaraptorid skeletons known. [1]

Maip was first announced in a Research Square preprint in 2021. However, since the paper did not meet the necessary requirements, the taxon was considered informally named. [3] In 2022, the fossil material was validly described as belonging to a new genus and species of megaraptorid by Rolando et al. The generic name, "Maip", references a malicious being in Aonikenk mythology that is "the shadow of death" that "kills with cold wind." The specific name, "macrothorax", is derived from the Greek "makrós", meaning "large", and the Latin "thorax", meaning "chest", in reference to its large thoracic cavity. [1]

Description

Size compared to a human Maip Size Comparison.svg
Size compared to a human

Maip is estimated to have been around 9–10 metres (30–33 ft) long in life. As such, it may be the largest megaraptorid currently known. Members of the Megaraptoridae as a whole increased in body length following the extinction of the carcharodontosaurids in the Southern Hemisphere in the early Late Cretaceous. [4] It is hypothesized that the absence of these large apex predators allowed other theropods to diversify and fill the empty niche space. Megaraptorids, in addition to abelisaurids and unenlagiids, then became the primary predators in their ecosystems. An analysis of known megaraptorans shows that members of the clade in Asia, South America, and Australia ranged from 4–4.5 metres (13–15 ft) long during the Barremian-Aptian, after which Aptian-early Turonian forms increased to 4.5–6 metres (15–20 ft) in Australia and South America. Turonian-Coniacian megaraptorids, only known from South America, were larger, at 6–7 metres (20–23 ft) long, and the final Santonian-Maastrichtian forms were larger still, at 7–10 metres (23–33 ft). [1]

Traces on the preserved ribs were interpreted by the describing authors as being attachment points for ligaments. From these, it was inferred that Maip would have likely had a respiratory system comparable to those of modern birds, rather than those of other extant reptiles, such as crocodilians. [1]

Classification

Life restoration Maip macrothorax reconstruction.jpg
Life restoration

In their phylogenetic analyses, Rolando et al. (2022) recovered Maip as a derived megaraptorid in a polytomy with other Argentinian megaraptorids. They also noted the presence of two distinct clades: a more inclusive clade, comprising all megaraptorids except Fukuiraptor and Australovenator , (shown below as "Clade A"), and a more exclusive clade of larger, entirely South American megaraptorids (shown below as "Clade B"). Like some previous analyses by other authors, Megaraptora is nested within Coelurosauria, as the sister taxon to Tyrannosauroidea. The cladogram below displays the megaraptoran results of the phylogenetic analyses by Rolando et al (2022). [1]

Megaraptora

Phuwiangvenator

Vayuraptor

Fukuiraptor

Megaraptoridae

Australian megaraptorid indet. (LRF 100–106)

Australovenator Australovenator.jpg

"Clade A"

Aoniraptor

Bajo Barreal Formation megaraptorid indet. (UNPSJB-Pv 944/958)

Paleoecology

Satellite image of the Chorrillo Formation area (middle right), the geological area where the Maip holotype was discovered Perito Moreno ISS.jpg
Satellite image of the Chorrillo Formation area (middle right), the geological area where the Maip holotype was discovered

Maip is known from the Maastrichtian-dated Chorrillo Formation of southern Argentina. Other named dinosaurs known from the formation include Isasicursor , an elasmarian ornithopod, and Nullotitan , a titanosaurian sauropod. [2] Indeterminate remains belonging to ankylosaurs, euiguanodontians, hadrosaurids, noasaurids, and unenlagiids have also been recovered from the formation. Fossils of indeterminate anurans, fish, mammals, mosasaurs, snakes, turtles, and gastropods are also known. [5] Very fragmentary fossil material, including teeth and a dorsal centrum, has been classified as having megaraptorid affinities, but it is too fragmentary to be assigned to Maip or any other taxon. [1]

Related Research Articles

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

Megaraptor is a genus of large theropod dinosaur that lived in the ages of the Late Cretaceous. Its fossils have been discovered in the Patagonian Portezuelo Formation of Argentina, South America. Initially thought to have been a giant dromaeosaur-like coelurosaur, it was classified as a neovenatorid allosauroid in previous phylogenies, but more recent phylogeny and discoveries of related megaraptoran genera has placed it as either a basal tyrannosauroid or a basal coelurosaur with some studies still considering it a neovenatorid.

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

Lametasaurus named for the Lameta Formation, Jabalpur, India, is the generic name given to a possibly chimeric dinosaur species. The type species is L. indicus.

<i>Rocasaurus</i> Genus of titanosaurian sauropod from the Late Cretaceous period

Rocasaurus is a genus of titanosaurian sauropod that lived in South America. Rocasaurus was discovered in Argentina in 2000, within the Allen Formation which is dated to be middle Campanian to early Maastrichtian in age. This genus grew up to 8 metres (26 ft) long, making it one of the smaller sauropods. It seems to be closely related to saltasaurid dinosaurs, like Saltasaurus and Neuquensaurus.

The Huincul Formation is a geologic formation of Late Cretaceous age of the Neuquén Basin that outcrops in the Mendoza, Río Negro and Neuquén Provinces of northern Patagonia, Argentina. It is the second formation in the Río Limay Subgroup, the oldest subgroup within the Neuquén Group. Formerly that subgroup was treated as a formation, and the Huincul Formation was known as the Huincul Member.

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

Orkoraptor is a genus of medium-sized megaraptoran theropod dinosaur from the late Cretaceous Period of Argentina. It is known from incomplete fossil remains including parts of the skull, teeth, tail vertebrae, and a partial tibia. The specialized teeth resemble those of some maniraptoriform theropods, namely the deinonychosaurs and compsognathids. This and other anatomical features led the authors who described it to suggest that it was a maniraptoran coelurosaur. However, subsequent studies found it to be a megaraptoran. Found in the Cerro Fortaleza Formation of Southern Patagonia, it is one of the southernmost carnivorous dinosaurs known from South America.

<span class="mw-page-title-main">Megaraptora</span> Extinct clade of dinosaurs

Megaraptora is a clade of carnivorous theropod dinosaurs. Its derived members, the Megaraptoridae are noted for their large hand claws and powerfully-built forelimbs, which are usually reduced in size in other large theropods.

<span class="mw-page-title-main">Chorrillo Formation</span> Geologic formation in southern Patagonia, Argentina

The Chorrillo Formation, also named as Chorillo Formation, is a Maastrichtian geologic formation in southern Patagonia, Argentina. The formation is more than 50 metres (160 ft) thick and underlies the Calafate Formation and rests on top of the La Irene Formation.

<i>Bonapartenykus</i> A large alvarezsauroid dinosaur

Bonapartenykus is a monospecific genus of alvarezsauroid dinosaur from Argentina that lived during the Late Cretaceous (Campanian-Maastrichtian) in what is now the upper Allen Formation of the Río Negro Province. The type and only species, Bonapartenykus ultimus, is known from a nearly articulated but partial skeleton that was found in close association to two incomplete eggs and several clusters of eggshells belonging to the oogenus Arriagadoolithus. Bonapartenykus was named in 2012 by Federico L. Agnolin, Jaime E. Powell, Fernando E. Novas and Martin Kundrát. Bonapartenykus has an estimated length of 2.5 m (8.2 ft) and weight of 72 kg (159 lb), making it the largest member of the clade Alvarezsauroidea.

Aoniraptor is a megaraptoran theropod from the Late Cretaceous of Argentina.

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

Phuwiangvenator is an extinct genus of megaraptoran theropod that lived during the Early Cretaceous period in what is now Thailand. It contains only the type species, P. yaemniyomi. The generic name of Phuwiangvenator comes from the Phu Wiang mountains, where the holotype was discovered, and the Latin word "venator" meaning hunter. The specific name, "yaemniyomi", is in honor of Sudham Yaemniyom, who was a historical paleontologist from Thailand and the first person to discover fossils there.

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.

Isasicursor is a genus of elasmarian ornithopod from the Chorrillo Formation from Santa Cruz Province in Argentina. The type and only species is Isasicursor santacrucensis. It was a contemporary of the sauropod Nullotitan which was described in the same paper.

<i>Niebla antiqua</i> Extinct species of dinosaur

Niebla is a genus of abelisaurid theropod dinosaur from the Late Cretaceous Period (Campanian-Maastrichtian) of Río Negro province, Argentina. The genus contains a single species, Niebla antiqua, and is known from a partial, non-articulated skeleton. The holotype, found in the Allen Formation, represents an adult individual.

<i>Meraxes</i> Genus of carcharodontosaurid dinosaurs

Meraxes is a genus of large carcharodontosaurid theropod dinosaur from the Late Cretaceous Huincul Formation of Patagonia, Argentina. The genus contains a single species, Meraxes gigas.

Patagopelta is an extinct genus of ankylosaurian dinosaur from the Late Cretaceous Allen Formation of Argentina. The genus contains a single species, P. cristata, known from a partial skeleton. While originally described as a nodosaurine, later discoveries provided support for parankylosaurian affinities for the taxon. Patagopelta is a very small ankylosaur, comparable in size to the dwarf nodosaurid Struthiosaurus, about 2 m (6.6 ft) long.

<i>Yatenavis</i> Extinct genus of birds

Yatenavis is an extinct genus of enantiornithine bird from the Late Cretaceous Chorrillo Formation of Santa Cruz Province, Argentina. The genus contains a single species, Y. ieujensis, known from a partial humerus.

<i>Patagorhynchus</i> Extinct genus of monotremes

Patagorhynchus is a genus of prehistoric monotreme mammal from the Late Cretaceous Chorrillo Formation of Santa Cruz Province, Argentina. The genus contains a single species, Patagorhynchus pascuali. The holotype, MPM-PV-23087, consists of a lower right molar attached to a fragment of the dentary. It was collected near Rio Gallegos, Santa Cruz, Argentina in 2022 and is housed in the Museo Padre Molina.

<i>Patagomaia</i> Extinct genus of mammals

Patagomaia is an extinct therian mammal from the Maastrichtian Chorrillo Formation of Argentina. It is the largest Mesozoic mammal yet known, with weight estimates of around 14 kilograms (31 lb). The type species is P. chainko.

<i>Chakisaurus</i> Extinct genus of ornithopod dinosaurs

Chakisaurus is an extinct genus of elasmarian ornithopod dinosaur from the Late Cretaceous Huincul Formation of Argentina. The genus contains a single species, C. nekul, known from multiple partial skeletons belonging to individuals of different ages. Chakisaurus represents the first ornithischian species to be named from the Huincul Formation.

References

  1. 1 2 3 4 5 6 7 Rolando, Alexis M. A.; Motta, Matias J.; Agnolín, Federico L.; Manabe, Makoto; Tsuihiji, Takanobu; Novas, Fernando E. (April 26, 2022). "A large Megaraptoridae (Theropoda: Coelurosauria) from Upper Cretaceous (Maastrichtian) of Patagonia, Argentina". Scientific Reports. 12 (1): Article number 6318. Bibcode:2022NatSR..12.6318A. doi: 10.1038/s41598-022-09272-z . PMC   9042913 . PMID   35474310.
  2. 1 2 Novas, Fernando; Agnolin, Federico; Rozadilla, Sebastián; Aranciaga-Rolando, Alexis; Brissón-Eli, Federico; Motta, Matias; Cerroni, Mauricio; Ezcurra, Martín; Martinelli, Agustin; D´Angelo, Julia; Álvarez-Herrera, Gerardo (2019). "Paleontological discoveries in the Chorrillo Formation (upper Campanian-lower Maastrichtian, Upper Cretaceous), Santa Cruz Province, Patagonia, Argentina". Revista del Museo Argentino de Ciencias Naturales. Nueva Serie. 21 (2): 217–293. doi: 10.22179/revmacn.21.655 . hdl: 11336/122229 . ISSN   1853-0400. S2CID   212808625.
  3. ↑ Rolando, Alexis M. A.; Motta, Matias J.; Agnolín, Federico L.; Manabe, Makoto; Tsuihiji, Takanobu; Novas, Fernando E. (December 22, 2021). "The Biggest Megaraptoridae (Theropoda: Coelurosauria) of South America" (PDF). Research Square: 1–43. doi:10.21203/rs.3.rs-1152394/v1.
  4. ↑ Meso, J. G.; Juárez Valieri, R. D.; Porfiri, J. D.; Correa, S. A. S.; Martinelli, A. G.; Casal, G. A.; Canudo, J. I.; Poblete, F.; Dos Santos, D. (September 1, 2021). "Testing the persistence of Carcharodontosauridae (Theropoda) in the Upper Cretaceous of Patagonia based on dental evidence". Cretaceous Research. 125: 104875. Bibcode:2021CrRes.12504875M. doi:10.1016/j.cretres.2021.104875. hdl: 11336/183886 . ISSN   0195-6671.
  5. ↑ Rozadilla, Sebastián; Agnolín, Federico; Manabe, Makoto; Tsuihiji, Takanobu; Novas, Fernando E. (September 1, 2021). "Ornithischian remains from the Chorrillo Formation (Upper Cretaceous), southern Patagonia, Argentina, and their implications on ornithischian paleobiogeography in the Southern Hemisphere". Cretaceous Research. 125: 104881. Bibcode:2021CrRes.12504881R. doi:10.1016/j.cretres.2021.104881. ISSN   0195-6671.
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