Effigia okeeffeae
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''Effigia'' was an
extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
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
shuvosaurid Shuvosauridae is an extinct family (biology), family of theropod-like pseudosuchians within the clade Poposauroidea. Shuvosaurids existed in North America (United States) and South America (Argentina) during the Late Triassic period (late Carnian ...
known from the
Late Triassic The Late Triassic is the third and final epoch (geology), epoch of the Triassic geologic time scale, Period in the geologic time scale, spanning the time between annum, Ma and Ma (million years ago). It is preceded by the Middle Triassic Epoch ...
of
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...
, south-western USA. With a bipedal stance, long neck, and a toothless beaked skull, ''Effigia'' and other shuvosaurids bore a resemblance to the
ornithomimid Ornithomimidae (meaning "bird-mimics") is a family of theropod dinosaurs which bore a superficial resemblance to modern ostriches. Ornithomimids were fast, omnivorous or herbivorous dinosaurs known mainly from the Late Cretaceous Period of Laura ...
dinosaurs 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 ...
of the
Cretaceous Period The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of t ...
. However, shuvosaurids were not dinosaurs, but were instead a specialized family of
poposauroid Poposauroidea is a clade of advanced pseudosuchians (archosaurs closer to crocodilians than to dinosaurs). It includes poposaurids, shuvosaurids, ctenosauriscids, and other unusual pseudosuchians such as ''Qianosuchus'' and ''Lotosaurus''. How ...
pseudosuchians Pseudosuchia is one of two major divisions of Archosauria, including living crocodilians and all archosaurs more closely related to crocodilians than to birds. Pseudosuchians are also informally known as "crocodilian-line archosaurs". Prior to ...
, meaning that their closest living relatives are
crocodilians Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period (Cenomanian stage) and are the closest living ...
.


Discovery

The 2-meter (6 ft 7 in)
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 ...
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
was collected by
Edwin H. Colbert Edwin Harris "Ned" Colbert (September 28, 1905 – November 15, 2001)O'Connor, Anahad ''The New York Times'', November 25, 2001. was a distinguished American vertebrate paleontologist and prolific researcher and author. Born in Clarinda, Iowa, he ...
in 1947. At this time Colbert led an excavation to collect blocks of rock from the Whitaker Quarry of
Ghost Ranch Ghost Ranch is a retreat and education center located close to the village of Abiquiú in Rio Arriba County in north central New Mexico, United States. It was the home and studio of Georgia O'Keeffe, as well as the subject of many of her painti ...
, near Abiquiu, New Mexico. Colbert's expedition intended to recover abundant fossils of the basal
theropod Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally c ...
dinosaur ''
Coelophysis ''Coelophysis'' ( traditionally; or , as heard more commonly in recent decades) is an extinct genus of coelophysid theropod dinosaur that lived approximately 228 to 201.3 million years ago during the latter part of the Triassic Period from t ...
'', and he believed that no other large
vertebrates Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
were present in the quarry. As a result, his crew did not even open the plaster jackets of most of the blocks that were shipped to the
American Museum of Natural History The American Museum of Natural History (abbreviated as AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. In Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 26 inter ...
. The plaster jacket containing the holotype of ''Effigia'' started to be prepared in 2004, and the specimen was uncovered by graduate student
Sterling Nesbitt Sterling Nesbitt (born March 25, 1982, in Mesa, Arizona) is an American paleontologist best known for his work on the origin and early evolutionary patterns of archosaurs. He is currently an associate professor at Virginia Tech in the Department of ...
at the AMNH. Nesbitt was opening jackets of blocks in order to find new specimens of ''Coelophysis''. Upon finding the remains of ''Effigia'', he instantly recognized this was not a dinosaur and proceeded to track down the rest of the blocks from that area of the quarry. Nesbitt and
Mark Norell Mark Allen Norell (born July 26, 1957) is an American paleontologist, acknowledged as one of the most important living vertebrate paleontologists. He is currently the chairman of paleontology and a research associate at the American Museum of Na ...
, curator at the museum, named it ''Effigia okeeffeae'' in January 2006 after
Georgia O'Keeffe Georgia Totto O'Keeffe (November 15, 1887 – March 6, 1986) was an American modernist artist. She was known for her paintings of enlarged flowers, New York skyscrapers, and New Mexico landscapes. O'Keeffe has been called the "Mother of Amer ...
, who spent many years at Ghost Ranch.


Convergence

''Effigia'' is noted for its remarkable similarity to
ornithomimid Ornithomimidae (meaning "bird-mimics") is a family of theropod dinosaurs which bore a superficial resemblance to modern ostriches. Ornithomimids were fast, omnivorous or herbivorous dinosaurs known mainly from the Late Cretaceous Period of Laura ...
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 ...
s. In 2007, Nesbitt's description demonstrated that ''Effigia'' was very similar to ''
Shuvosaurus ''Shuvosaurus'' (meaning "Shuvo's lizard") is a genus of beaked reptile from the Late Triassic of western Texas. Despite looking superficially similar to a theropod dinosaur, it is actually more closely related to crocodilians. Discovery and ...
'', and is definitely a member of the archosaur subgroup Pseudosuchia (the line leading towards modern
crocodilia Crocodilia (or Crocodylia, both ) is an order of mostly large, predatory, semiaquatic reptiles, known as crocodilians. They first appeared 95 million years ago in the Late Cretaceous period ( Cenomanian stage) and are the closest living ...
ns). Its similarity to ornithomimids represents a case of "extreme"
convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...
. Nesbitt also demonstrated that ''
Shuvosaurus ''Shuvosaurus'' (meaning "Shuvo's lizard") is a genus of beaked reptile from the Late Triassic of western Texas. Despite looking superficially similar to a theropod dinosaur, it is actually more closely related to crocodilians. Discovery and ...
'' was the same animal as ''Chatterjeea'', and that it belonged to an exclusive
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, ...
containing closely related
suchians Suchia is a clade of archosaurs containing the majority of pseudosuchians (crocodilians and their extinct relatives). It was defined as the least inclusive clade containing '' Aetosaurus ferratus'', '' Rauisuchus tiradentes'', '' Prestosuchus ...
such as ''Shuvosaurus'' and ''
Poposaurus ''Poposaurus'' (" Popo Agie reptile") is an extinct genus of pseudosuchian archosaur from the Late Triassic of the southwestern United States. It belongs to the clade Poposauroidea, an unusual group of Triassic pseudosuchians that includes sail- ...
'' (
Poposauroidea Poposauroidea is a clade of advanced pseudosuchians (archosaurs closer to crocodilians than to dinosaurs). It includes poposaurids, shuvosaurids, ctenosauriscids, and other unusual pseudosuchians such as ''Qianosuchus'' and ''Lotosaurus''. How ...
). Within this group, ''Effigia'' forms an even more exclusive clade with ''Shuvosaurus'' and the South American ''
Sillosuchus ''Sillosuchus'' is a genus of shuvosaurid poposauroid archosaur that lived in South America during the Late Triassic period. Shuvosaurids were an unusual family of reptiles belonging to the group Poposauroidea; although their closest modern rel ...
'' (
Shuvosauridae Shuvosauridae is an extinct family of theropod-like pseudosuchians within the clade Poposauroidea. Shuvosaurids existed in North America (United States) and South America (Argentina) during the Late Triassic period (late Carnian to Rhaetian stag ...
).Nesbitt, S. (2007). "The anatomy of ''Effigia okeeffeae'' (Archosauria, Suchia), theropod-like convergence, and the distribution of related taxa." ''Bulletin of the American Museum of Natural History'', 302: 84 pp. http://digitallibrary.amnh.org/dspace/handle/2246/5840 In 2007, Lucas and others suggested that "''Effigia''" was synonymous with "''Shuvosaurus''" and used the new combination "''Shuvosaurus okeeffeae''" for the animal. This proposal has not been accepted by other archosaur workers.


Paleobiology

Examination of ''Effigia's'' jaws suggest it nipped and sheared off vegetation when feeding, due to its weak jaws and sharp beak. It was previously suggested that it pecked for food like
ostriches Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There are ...
or other
ratites A ratite () is any of a diverse group of flightless, large, long-necked, and long-legged birds of the infraclass Palaeognathae. Kiwi, the exception, are much smaller and shorter-legged and are the only nocturnal extant ratites. The systematics o ...
, but biomechanical studies have estimated that its skull could not withstand such forces.


References


External links


''Effigia'' at the website for the 2007 IMAX documentary, "Dinosaurs Alive!

Toothless Crocodile Relative, 210 Million Years Old, Walked On Two Feet (2006) - American Museum of Natural History press release


* ttps://www.nytimes.com/2006/01/26/science/26croc.html?_r=2 Fossil Yields Surprise Kin of Crocodiles (2006) – New York Times press release {{Taxonbar, from=Q2324943 Poposauroids Late Triassic archosaurs of North America Prehistoric pseudosuchian genera