''Aristosuchus'' is a genus of small

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 ...

ian

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 ...

whose name was derived from the

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

ἄριστος (meaning bravest, best, noblest) and ''σουχος'' (the Ancient Greek corruption of the name of the

Egyptian Egyptian describes something of, from, or related to Egypt. Egyptian or Egyptians may refer to: Nations and ethnic groups * Egyptians, a national group in North Africa ** Egyptian culture, a complex and stable culture with thousands of years of ...

crocodile-headed god

Sobek Sobek (also called Sebek or Sobki, cop, Ⲥⲟⲩⲕ, Souk) was an ancient Egyptian deity with a complex and elastic history and nature. He is associated with the Nile crocodile or the West African crocodile and is represented either in its f ...

). It shared many characteristics with birds.

Discovery

The type species, ''Aristosuchus pusillus'', was described in 1876 by

Richard Owen Sir Richard Owen (20 July 1804 – 18 December 1892) was an English biologist, comparative anatomist and paleontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils. Owe ...

and named ''Poekilopleuron pusillus''. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

means "small" in

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

Harry Govier Seeley Harry Govier Seeley (18 February 1839 – 8 January 1909) was a British paleontologist. Early life Seeley was born in London on 18 February 1839, the second son of Richard Hovill Seeley, a goldsmith, and his second wife Mary Govier. When his fat ...

(1839–1909) gave it the name ''Aristosuchus'' in 1887. It was found in the Wealden Group dating to the

Early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

(

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded ...

) in

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

, on the

Isle of Wight The Isle of Wight ( ) is a county in the English Channel, off the coast of Hampshire, from which it is separated by the Solent. It is the largest and second-most populous island of England. Referred to as 'The Island' by residents, the Isle of ...

, i.e. from about 125 million years ago.

Description

''Aristosuchus'' was a

biped Bipedalism is a form of terrestrial locomotion where an organism moves by means of its two rear limbs or legs. An animal or machine that usually moves in a bipedal manner is known as a biped , meaning 'two feet' (from Latin ''bis'' 'double' a ...

al, meat-eating (

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...

)

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. This predator is thought to have been about and is estimated to have weighed about . According to

Gregory S. Paul Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod dino ...

, its weight was . The femur of ''Aristosuchus'' has a wing-like anterior

trochanter A trochanter is a tubercle of the femur near its joint with the hip bone. In humans and most mammals, the trochanters serve as important muscle attachment sites. Humans are known to have three trochanters, though the anatomic "normal" includes ...

and a markedly reduced fourth trochanter.

Classification

''Aristosuchus'' was originally named as a new species of ''

Poekilopleuron ''Poekilopleuron'' (meaning "varied ribs") is a genus of tetanuran dinosaur, which lived during the middle Bathonian of the Jurassic, about 168 to 166 million years ago. The genus has been used under many different spelling variants, although on ...

'', ''P. pusillus'', from the Wessex Formation of the Isle of Wight. Woodward and Sherborn (1890) regarded ''Aristosuchus pusillus'' as being based on the same specimen that Reverend William D. Fox named ''Calamospondylus oweni'' in 1866, and many authors followed suit (some regarding ''C. oweni'' as a ''nomen nudum'').Norman, D.B. 1985. The Illustrated Encyclopedia of Dinosaurs. Salamander, London. However, Naish (1999, 2002) showed that ''Calamospondylus'' was based on a different specimen than the ''Aristosuchus'' holotype based on letters of correspondence between Richard Owen and Reverend Fox as well as discrepancies in the original description.NAISH, D. 2002. The historical taxonomy of the Lower Cretaceous theropods (Dinosauria) Calamospondylus and Aristosuchus from the Isle of Wight. ''Proceedings of the Geologists’ Association'' 113: 153–163. Naish (1999, 2002) placed ''Aristosuchus'' in

Compsognathidae Compsognathidae is a family of coelurosaurian theropod dinosaurs. Compsognathids were small carnivores, generally conservative in form, hailing from the Jurassic and Cretaceous Periods. The bird-like features of these species, along with other d ...

.Naish, D. 1999. Fox, Owen and the small Wealden theropods Calamospondylus and Aristosuchus. Journal of Vertebrate Paleontology, 19 (Suppl. 3), 66. ''Aristosuchus'' is known from

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 ...

NHMUK R.178: a

sacrum The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part ...

, a pubis, a

femur The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates with ...

and a few

vertebra The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...

e. Two ungual

phalanges The phalanges (singular: ''phalanx'' ) are digital bones in the hands and feet of most vertebrates. In primates, the thumbs and big toes have two phalanges while the other digits have three phalanges. The phalanges are classed as long bones. ...

were found nearby, which may have been from the same animal and would suggest long claws.

Discovery

Description

Classification

References

Further reading