''Effigia'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of shuvosaurid 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 a ...

New Mexico New Mexico is a state in the Southwestern United States, Southwestern region of the United States. It is one of the Mountain States of the southern Rocky Mountains, sharing the Four Corners region with Utah, Colorado, and Arizona. It also ...

, south-western USA. With a bipedal stance, long neck, and a toothless beaked skull, ''Effigia'' and other shuvosaurids bore a resemblance to the ornithomimid

dinosaurs Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

of the

Cretaceous Period The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 77.1 million years, it is the ninth and longest geologi ...

. However, shuvosaurids were not dinosaurs, but were instead a specialized family of poposauroid pseudosuchians, meaning that their closest living relatives are

crocodilians Crocodilia () is an order of semiaquatic, predatory reptiles that are known as crocodilians. They first appeared during the Late Cretaceous and are the closest living relatives of birds. Crocodilians are a type of crocodylomorph pseudosuchi ...

Discovery

The 2-meter (6 ft 7 in)

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

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 preserve ...

was collected by Edwin H. Colbert 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 in Rio Arriba County in north central New Mexico, United States. It is about 65 miles northwest of Santa Fe and 14 miles from Abiquiu, the nearest community. In the later 20th century, it was the ...

, near Abiquiu, New Mexico. Colbert's expedition intended to recover abundant fossils of the basal

theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

dinosaur ''

Coelophysis ''Coelophysis'' ( Traditional English pronunciation of Latin, traditionally; or , as heard more commonly in recent decades) is a genus of coelophysid Theropoda, theropod dinosaur that lived Approximation, approximately 215 to 201.4 million y ...

'', and he believed that no other large

vertebrates Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

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 (AMNH) is a natural history museum on the Upper West Side of Manhattan in New York City. Located in Theodore Roosevelt Park, across the street from Central Park, the museum complex comprises 21 interconn ...

. 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 Departme ...

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, 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 Modernism, modernist painter and drafter, draftswoman whose career spanned seven decades and whose work remained largely independent of major art movements. Called the "M ...

, who spent many years at Ghost Ranch.

Convergence

''Effigia'' is noted for its remarkable similarity to ornithomimid

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

s. In 2007, Nesbitt's description demonstrated that ''Effigia'' was very similar to ''

Shuvosaurus ''Shuvosaurus'' (meaning "Shuvo hatterjees lizard") is a genus of beaked, bipedal poposauroid pseudosuchian from the Late Triassic (early to middle Norian) of western Texas. Despite superficially resembling a Theropoda, theropod dinosaur, es ...

'', and is definitely a member of the archosaur subgroup Pseudosuchia (the line leading towards modern

crocodilia Crocodilia () is an order of semiaquatic, predatory reptiles that are known as crocodilians. They first appeared during the Late Cretaceous and are the closest living relatives of birds. Crocodilians are a type of crocodylomorph pseudosuchia ...

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 comm ...

. Nesbitt also demonstrated that ''

'' was the same animal as ''Chatterjeea'', and that it belonged to an exclusive

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

containing closely related suchians such as ''Shuvosaurus'' and ''

Poposaurus ''Poposaurus'' is an extinct genus of pseudosuchian archosaur from the Late Triassic of the southwestern and eastern United States. It belongs to the clade Poposauroidea, an unusual group of Triassic pseudosuchians that includes sail-backed, bea ...

'' (

Poposauroidea Poposauroidea is a clade of advanced Pseudosuchian, pseudosuchians. It includes poposaurids, Shuvosaurinae, shuvosaurids, ctenosauriscids, and other unusual pseudosuchians such as ''Qianosuchus'' and ''Lotosaurus''. It excludes most large predato ...

). Within this group, ''Effigia'' forms an even more exclusive clade with ''Shuvosaurus'' and the South American '' Sillosuchus'' ( Shuvosauridae).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 Nesbitt.

Paleobiology

Examination of ''Effigia's'' jaws suggest it was a specialist herbivore that filled a niche as a browser feeding on softer plant material, due to its weak jaws and sharp beak. It was previously suggested that it pecked for food like

ostriches Ostriches are large flightless birds. Two living species are recognised, the common ostrich, native to large parts of sub-Saharan Africa, and the Somali ostrich, native to the Horn of Africa. They are the heaviest and largest living birds, w ...

or other

ratites Ratites () are a polyphyletic group consisting of all birds within the infraclass Palaeognathae that lack keel (bird anatomy), keels and flightless bird, cannot fly. They are mostly large, long-necked, and long-legged, the exception being the Kiw ...

, 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 {{Taxonbar, from=Q2324943 Poposauroidea Late Triassic archosaurs of North America Prehistoric pseudosuchian genera