Macrogryphosaurus
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''Macrogryphosaurus'' (meaning "big enigmatic lizard") is a
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
of
elasmaria Elasmaria is a clade of ornithopods known from Cretaceous deposits in South America, Antarctica, and Australia that contains many bipedal ornithopods that were previously considered "hypsilophodonts".Madzia, Daniel; Boyd, Clint A.; Mazuch, Marti ...
n
dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...
from the
Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by t ...
age
Upper Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
Sierra Barrosa Formation (
Neuquén Group The Neuquén Group is a group of geologic formations found in Argentina. Rocks in the Neuquén Group fall within the Cenomanian to early Campanian stages of the Late Cretaceous Period. It overlies the older Lohan Cura Formation and is itself over ...
) of
Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
in
Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...
. It was described by Jorge Calvo and colleagues in 2007, with ''M. gondwanicus'' as the type and only species.


Discovery and naming

In May 1999, during field work at Mari Menuco Lake,
Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
(sixty kilometres northwest of
Neuquén Neuquén (; arn, Nehuenken) is the capital city of the Argentine province of Neuquén and of the Confluencia Department, located in the east of the province. It occupies a strip of land west of the confluence of the Limay and Neuquén rivers w ...
) conducted by the
National University of Comahue The National University of Comahue ( es, Universidad Nacional del Comahue, UNCNavarro, Fernando A. ''. Tremédica, Asociación Internacional de Traductores y Redactores de Medicina y Ciencias Afines/UNCoPortal de Prensa de la Uncoma, Universidad ...
, an articulated, nearly complete dinosaur skeleton was discovered and excavated. It was brought to the attention of the palaeontologists by young boy Rafael Moyano, who had discovered it.Poropat, S. F. The Winston Churchill Memorial Trust of Australia.
/ref> Originally reported to hail from the
Portezuelo Formation The Portezuelo Formation is a geologic formation of Late Cretaceous ( Late Turonian to Early Coniacian) age, outcropping in the Mendoza, Río Negro and Neuquén provinces of Argentina.Neuquén Group The Neuquén Group is a group of geologic formations found in Argentina. Rocks in the Neuquén Group fall within the Cenomanian to early Campanian stages of the Late Cretaceous Period. It overlies the older Lohan Cura Formation and is itself over ...
, its locality was later revised to be in the Sierra Barrosa Formation of the same geologic group. These unit is dated to the
Coniacian The Coniacian is an age or stage in the geologic timescale. It is a subdivision of the Late Cretaceous Epoch or Upper Cretaceous Series and spans the time between 89.8 ± 1 Ma and 86.3 ± 0.7 Ma (million years ago). The Coniacian is preceded by t ...
age Age or AGE may refer to: Time and its effects * Age, the amount of time someone or something has been alive or has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...
of the
Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the ...
. Noted for bony plates on its thorax, it was identified as a large species of ornithopod. The species would be described and named ''Macrogryphosaurus gondwanicus'' in 2007, in a study authored by Jorge O. Calvo, Juan D. Porfiri, and Fernando E. Novas. Its generic name was derived from the Greek ''macro'', meaning large, ''grypho'', meaning enigmatic, and ''saurus'', meaning lizard. The specific epiphet ''gondwanicus'' refers to the ancient continent of
Gondwana Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages ...
. The
holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...
specimen, MUCPv-32, consists of an essentially complete set of vertebra, a number of ribs, four mineralized thoracic plates, both sides of the pectoral girdle, and a sternum. The individual is considered to have been an adult. The preservation of the fossil was described by Dr. Stephen F. Poropat as "amazing" in nature. Subsequent research has not referred any other specimens to the species. However, in 2016, a study was published on MAU-Pv-PH-458, a fragmentary dorsal neural arch from the Plottier Formation of northern Argentina. The bone is the northernmost record of an ornithopod in South America. It was not determined to belong to a ''Macrogryphosaurus'', but noted to be from an animal of similar size and anatomy, and from approximately the same geographic and
stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostra ...
location, though it lived at a slightly earlier time. Other indeterminate ornithopod specimens from Argentina similarly indicate animals of similar size to the
taxon In biology, a taxon (back-formation from ''taxonomy''; plural taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular nam ...
. ''M. gondwanicus'' received a complete osteology in 2020, a study published in Cretaceous Research by Sebastián Rozadilla, Penélope Cruzado-Caballero, Jorge O. Calvo. This described the anatomy of the species in much more thoroughly and investigating its classification and biomechanics under a more modern lens. They considered the genus to be of importance, due to being the largest known elasmarian species, and for the completeness of its known remains, informing on the anatomy of the group.


Description

''Macrogryphosaurus'' has been noted for its large size compared to other South American ornithopods. It has been estimated to have been around in length, though the only known individual may not have been fully grown. Gregory S. Paul estimated the length of this specimen at in length and in body mass. As such, it is the largest species of South American
ornithopod Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous wo ...
outside of
Hadrosauridae Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which includ ...
, and the largest species of elasmarian. Approaching the size of many more derived iguanodontian ornithopods, it is, compared to these derived taxa, much more graceful and lightly built in form. One of the most remarked upon features of the taxon is its mineralized thoracic plates, also referred to as intercostal plates. These are a series of plates along the side of the torso, shared with a handful of other ornithischians such as ''
Talenkauen ''Talenkauen'' is a genus of basal iguanodont dinosaur from the Campanian or Maastrichtian age of the Late Cretaceous Cerro Fortaleza Formation, formerly known as the Pari Aike Formation of Patagonian Lake Viedma, in the Austral Basin of Sant ...
'', ''
Thescelosaurus ''Thescelosaurus'' ( ; ancient Greek - (''-'') meaning "godlike", "marvellous", or "wondrous" and (') "lizard") was a genus of small neornithischian dinosaur that appeared at the very end of the Late Cretaceous period in North America. It was ...
'', and ''
Hypsilophodon ''Hypsilophodon'' (; meaning "''Hypsilophus''-tooth") is a neornithischian dinosaur genus from the Early Cretaceous period of England. It has traditionally been considered an early member of the group Ornithopoda, but recent research has put thi ...
''. Along with a fused, birdlike sternum, its short torso would have been rather stiff in nature. This, alongside its relatively elongate neck and
coelurosaur Coelurosauria (; from Greek, meaning "hollow tailed lizards") is the clade containing all theropod dinosaurs more closely related to birds than to carnosaurs. Coelurosauria is a subgroup of theropod dinosaurs that includes compsognathids, tyran ...
-like tail, gave it a rather unique form compared to that documented in other ornithischian dinosaurs.


Classification

Phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
analysis indicates that it is related to ''
Talenkauen ''Talenkauen'' is a genus of basal iguanodont dinosaur from the Campanian or Maastrichtian age of the Late Cretaceous Cerro Fortaleza Formation, formerly known as the Pari Aike Formation of Patagonian Lake Viedma, in the Austral Basin of Sant ...
'', and Calvo and colleagues proposed a new
clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
,
Elasmaria Elasmaria is a clade of ornithopods known from Cretaceous deposits in South America, Antarctica, and Australia that contains many bipedal ornithopods that were previously considered "hypsilophodonts".Madzia, Daniel; Boyd, Clint A.; Mazuch, Marti ...
, for the two genera. The
cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ...
below results from analysis by Herne ''et al.'', 2019.


References


External links

* * {{Taxonbar, from=Q138604 Ornithopods Coniacian life Turonian life Late Cretaceous dinosaurs of South America Cretaceous Argentina Fossils of Argentina Portezuelo Formation Fossil taxa described in 2007 Taxa named by Fernando Novas Ornithischian genera