"Death Shadow" Megaraptorid Dinosaur Unearthed in Argentina

[rogue06]

Researchers in Argentina have announced the discovery of a previously unknown type of megaraptor dinosaur that lived some 90 mya (Late Cretaceous) and apparently represents the largest species known from this group.

The discovery of the partial and disarticulated skeleton was made in the Chorrillo Formation of the southern Patagonia region of Santa Cruz Province, near the southern end of Argentina, which also makes it the southern-most megaraptor ever discovered. It consists mostly of vertebrae and ribs along with a fragmented scapula, partial pubis, and partial metatarsal, but does not include any cranial material.

Comparing it to other megaraptors, the team concluded that the creature was approximately 9 to 10 meters (29.5-32.75') long and weighed somewhere between 5 and 6 tons (press reports provide different estimates).

The lead author of the paper describing the find, Alexis Aranciaga Rolando, a paleontologist with the Argentine Museum of Natural Sciences, says the discovery fulfilled a childhood dream of his since he specializes in macroraptors.

He said it would have been the apex predator in the region at the time and named it Maip macrothorax, with the first part, or the genus name, being derived from an evil entity from the myths of the nearby indigenous Aonikenk people, and represents "the shadow of the death" which "kills with cold wind" in the Andes mountains.

The second part, or species name, comes from combining the Latin word for big or long, with thorax, and refers to its broad thoracic, or chest, cavity, which is over 1.2 meters (just under 4') wide.

Source: New Carnivorous Dinosaur Unearthed in Argentina

Paleontologists have described a new species of large-bodied megaraptoran dinosaur from fossilized remains found in Patagonia, Argentina.

The newly-identified dinosaur species lived in what is now Argentina some 70 million years ago (Maastrichtian age of the Cretaceous period).

Scientifically named Maip macrothorax, the ancient creature was between 9 and 10 m (29.5-32.8 feet) long and weighed up to 5 tons.

It belonged to Megaraptora, a group of theropod dinosaurs known from Gondwana landmasses and Asia.

“Megaraptorans are a group of predatory dinosaurs that inhabited Asia, Australia and South America from Barremian through Maastrichtian times,” said CONICET paleontologist Mauro Aranciaga Rolando and colleagues.

“Most members of this group are known from the Early to Late Cretaceous, with Maastrichtian megaraptorans known only from isolated and poorly informative remains.”

“These theropods are diagnosed by their elongate skulls, the presence of apicobasally short and strongly curved teeth that are 8-shaped in cross section, highly pneumatic axial skeleton reaching to the mid-caudal vertebrae, and long and powerful arms bearing large and sharp manual claws on digits I and II.”

“Although some authors have interpreted megaraptorans as an archaic group of allosauroid theropods, increasing evidence lends support to the hypothesis that they are, instead, members of Coelurosauria.”

“Aside from the consensus currently arrived on the phylogenetic allocation of Megaraptora among Coelurosauria, the internal relations of this group remain poorly resolved.”

The partial skeleton of Maip macrothorax was recovered from the Chorrillo Formation in southwestern Santa Cruz Province, Argentina.

The specimen is the most informative megaraptoran dinosaur known from Maastrichtian age.

“Maip macrothorax’s bones helped us better understand the anatomy of megaraptors,” Dr. Rolando said.

“They belong to a family whose skeleton was not like that of a tyrannosaurus — large and heavy — but rather light animals.”

“In other words, their bones were not solid, but rather had a large number of internal voids that made them much lighter, something like a hollow brick compared to a solid one.”

“Besides, they had long tails and long legs, which also corroborates that they were relatively agile animals.”

“The most characteristic of these dinosaurs are their arms: long, gigantic, topped by claws up to 35 cm (13.8 inches) long, with which we infer that they grabbed and tore their victims to pieces.”

“They were their main weapon, as their teeth were sharp but small.”

According to the researchers, Maip macrothorax and other South American megaraptorans belong to a monophyletic group, whereas Australian and Asian members constitute successive stem groups.

“South American forms differ from more basal megaraptorans in several anatomical features and in being much larger and more robustly built,” they said.



Source

© Copyright Original Source

The paper itself, A large Megaraptoridae (Theropoda: Coelurosauria) from Upper Cretaceous (Maastrichtian) of Patagonia, Argentina, can be read in its entirety by clicking the hyperlink, and the abstract can be read below:

Abstract

Megaraptora is a theropod clade known from former Gondwana landmasses and Asia. Most members of the clade are known from the Early to Late Cretaceous (Barremian–Santonian), with Maastrichtian megaraptorans known only from isolated and poorly informative remains. The aim of the present contribution is to describe a partial skeleton of a megaraptorid from Maastrichtian beds in Santa Cruz Province, Argentina. This new specimen is the most informative megaraptoran known from Maastrichtian age, and is herein described as a new taxon. Phylogenetic analysis nested the new taxon together with other South American megaraptorans in a monophyletic clade, whereas Australian and Asian members constitute successive stem groups. South American forms differ from more basal megaraptorans in several anatomical features and in being much larger and more robustly built.

1e569102-f907-4be5-a291-a80a84837260.jpg
(A), silhouette of showing the preserved bones in white. (B), reconstruction of the thoracic
cavity of Maip at level of D6. (C), interpretative drawing of the excavation of Maip showing the original
disposition of the bones. Abbreviations: a, axis; c, coracoid; ind, indeterminate bone; g, gastralia; r, rib; v, vertebrae.

maip_macrothorax_by_illustratedmenagerie_df4ehcu-fullview.jpg
Artist's reconstruction

[shunyadragon]

Researchers in Argentina have announced the discovery of a previously unknown type of megaraptor dinosaur that lived some 90 mya (Late Cretaceous) and apparently represents the largest species known from this group.

The discovery of the partial and disarticulated skeleton was made in the Chorrillo Formation of the southern Patagonia region of Santa Cruz Province, near the southern end of Argentina, which also makes it the southern-most megaraptor ever discovered. It consists mostly of vertebrae and ribs along with a fragmented scapula, partial pubis, and partial metatarsal, but does not include any cranial material.

Comparing it to other megaraptors, the team concluded that the creature was approximately 9 to 10 meters (29.5-32.75') long and weighed somewhere between 5 and 6 tons (press reports provide different estimates).

The lead author of the paper describing the find, Alexis Aranciaga Rolando, a paleontologist with the Argentine Museum of Natural Sciences, says the discovery fulfilled a childhood dream of his since he specializes in macroraptors.

He said it would have been the apex predator in the region at the time and named it Maip macrothorax, with the first part, or the genus name, being derived from an evil entity from the myths of the nearby indigenous Aonikenk people, and represents "the shadow of the death" which "kills with cold wind" in the Andes mountains.

The second part, or species name, comes from combining the Latin word for big or long, with thorax, and refers to its broad thoracic, or chest, cavity, which is over 1.2 meters (just under 4') wide.

Source: New Carnivorous Dinosaur Unearthed in Argentina

Paleontologists have described a new species of large-bodied megaraptoran dinosaur from fossilized remains found in Patagonia, Argentina.

The newly-identified dinosaur species lived in what is now Argentina some 70 million years ago (Maastrichtian age of the Cretaceous period).

Scientifically named Maip macrothorax, the ancient creature was between 9 and 10 m (29.5-32.8 feet) long and weighed up to 5 tons.

It belonged to Megaraptora, a group of theropod dinosaurs known from Gondwana landmasses and Asia.

“Megaraptorans are a group of predatory dinosaurs that inhabited Asia, Australia and South America from Barremian through Maastrichtian times,” said CONICET paleontologist Mauro Aranciaga Rolando and colleagues.

“Most members of this group are known from the Early to Late Cretaceous, with Maastrichtian megaraptorans known only from isolated and poorly informative remains.”

“These theropods are diagnosed by their elongate skulls, the presence of apicobasally short and strongly curved teeth that are 8-shaped in cross section, highly pneumatic axial skeleton reaching to the mid-caudal vertebrae, and long and powerful arms bearing large and sharp manual claws on digits I and II.”

“Although some authors have interpreted megaraptorans as an archaic group of allosauroid theropods, increasing evidence lends support to the hypothesis that they are, instead, members of Coelurosauria.”

“Aside from the consensus currently arrived on the phylogenetic allocation of Megaraptora among Coelurosauria, the internal relations of this group remain poorly resolved.”

The partial skeleton of Maip macrothorax was recovered from the Chorrillo Formation in southwestern Santa Cruz Province, Argentina.

The specimen is the most informative megaraptoran dinosaur known from Maastrichtian age.

“Maip macrothorax’s bones helped us better understand the anatomy of megaraptors,” Dr. Rolando said.

“They belong to a family whose skeleton was not like that of a tyrannosaurus — large and heavy — but rather light animals.”

“In other words, their bones were not solid, but rather had a large number of internal voids that made them much lighter, something like a hollow brick compared to a solid one.”

“Besides, they had long tails and long legs, which also corroborates that they were relatively agile animals.”

“The most characteristic of these dinosaurs are their arms: long, gigantic, topped by claws up to 35 cm (13.8 inches) long, with which we infer that they grabbed and tore their victims to pieces.”

“They were their main weapon, as their teeth were sharp but small.”

According to the researchers, Maip macrothorax and other South American megaraptorans belong to a monophyletic group, whereas Australian and Asian members constitute successive stem groups.

“South American forms differ from more basal megaraptorans in several anatomical features and in being much larger and more robustly built,” they said.



Source

© Copyright Original Source

The paper itself, A large Megaraptoridae (Theropoda: Coelurosauria) from Upper Cretaceous (Maastrichtian) of Patagonia, Argentina, can be read in its entirety by clicking the hyperlink, and the abstract can be read below:

Abstract

Megaraptora is a theropod clade known from former Gondwana landmasses and Asia. Most members of the clade are known from the Early to Late Cretaceous (Barremian–Santonian), with Maastrichtian megaraptorans known only from isolated and poorly informative remains. The aim of the present contribution is to describe a partial skeleton of a megaraptorid from Maastrichtian beds in Santa Cruz Province, Argentina. This new specimen is the most informative megaraptoran known from Maastrichtian age, and is herein described as a new taxon. Phylogenetic analysis nested the new taxon together with other South American megaraptorans in a monophyletic clade, whereas Australian and Asian members constitute successive stem groups. South American forms differ from more basal megaraptorans in several anatomical features and in being much larger and more robustly built.

1e569102-f907-4be5-a291-a80a84837260.jpg
(A), silhouette of showing the preserved bones in white. (B), reconstruction of the thoracic
cavity of Maip at level of D6. (C), interpretative drawing of the excavation of Maip showing the original
disposition of the bones. Abbreviations: a, axis; c, coracoid; ind, indeterminate bone; g, gastralia; r, rib; v, vertebrae.

maip_macrothorax_by_illustratedmenagerie_df4ehcu-fullview.jpg
Artist's reconstruction

Neat! Thanks for the reference!