CERATOSAURUS
a meat-eating ceratosaurid theropod dinosaur from the Late Jurrasic of North America.
Pronunciation: suh-RAT-o-SOR-us
Meaning: Horned Lizard
Author/s: Marsh (
1884)
Synonyms: Megalosaurus nasicornis
First Discovery: Colorado, USA
Discovery Chart Position: #61
Ceratosaurus nasicornis
Like all things, the theropod family tree isn't just black and white, and somewhere between the primitive coelophysoids and the advanced tetanurans, a particular group of carnivores branched off to do their own thing. These were the ceratosaurs, named after
Ceratosaurus, who were among the most common meat-eaters in North America's Morrison Formation. However, fossils from Tanzania, Portugal, Switzerland and Uruguay have been assigned here too, in several cases as entirely new species, but they're mostly fragmentary or non-diagnostic, and many palaeontologists are sceptical of their validity at pretty much every level.
Looks-wise,
Ceratosaurus is hard to miss: a proportionately oversized head, small but powerful arms, a row of small osteoderms running the midline of its neck, back and tail and, of course, a name-prompting snout horn plus a cluster of modest hornlets just in front of its eyes. At around six meters long and under a ton in weight, it wasn't in the same league as
Saurophaganax,
Allosaurus, and
Torvosaurus. But being behind the Morrison-bossing trifecta of predators who gorged on the meatiest of prey was far from a bad thing, as this just might've left a nice little niche for
Ceratosaurus to exploit, but then again, it might not have.
Because of a somewhat sleek design and long, flexible, crocodile-like tail, some palaeontologists have suggested that
Ceratosaurus was built for an aquatic lifestyle, or at least for marine hunting. Its insanely long, flattened, meat-slicing teeth seem all wrong for tackling large, struggling, land-bound prey but ideal for nabbing fish. However, others have rubbished this theory, but regardless, no predator is too proud to scavenge, and
Ceratosaurus tooth marks on ground-found fossils show that terrestrial dinosaurs were on the menu when a carcass was there for the taking.
(Horned Lizard with a Nose Horn)Etymology
Ceratosaurus is derived from the Greek "keras" (horned) and "sauros" (lizard), referring to the horn on its snout.
The
species epithet,
nasicornis (nay-si-CORN-iss), is derived from the Latin "nasus" (nose) and "cornis" (horned) which refers to... the horn on its snout.
Discovery
The first fossils of
Ceratosaurus were discovered at "Felch Quarry 1" in the Morrison Formation at Garden Park, Colorado, USA by farmer Marshall Parker Felch in 1883.
The
holotype (USNM 4735) is a complete but heavily distorted skull and nearly complete skeleton.
Well over a century later, this remains the most complete
Ceratosaurus specimen ever discovered.
Estimations
Timeline:
Era: Mesozoic
Epoch: Late Jurassic
Stage: Kimmeridgian
Age range: 156-151 mya
Stats:
Est. max. length: 6 meters
Est. max. hip height: 1.8 meters
Est. max. weight: 750 Kg
Diet: Carnivore
Other species
Ceratosaurus ingens was attributed to Werner Janensch by Rowe and Gauthier in 1990 for a gigantic theropod tooth from "Quarry B" in the Upper Saurian level at Tendaguru. However, Janensch had actually assigned this tooth to
Megalosaurus(?) ingens not
Ceratosaurus ingens, in 1920. At 15cm long, the tooth is unlikely to belong to
Ceratosaurus, and according to Rauhut (2011) it doesn't belong to
Megalosaurus either.
Ceratosaurus ingens possibly represents a carcharodontosaurid, but it's not Egypt's
Bahariyasaurus ingens which is also a carcharodontosaurid and has the same epithet.
Ceratosaurus magnicornis was named by Madsen and Welles in 1990 based on a nearly complete skeleton (MWC 1) from the Fruita Paleontontological Area in the Lower part of the Brushy Basin Member of the
Morrison Formation. It differs from
Ceratosaurus nasicornis in having a longer and lower skull, and a proportionately larger and more rounded nasal horncore. The name is derived from the Latin "magni" (large, great) and "cornis" (horned). Although large, this specimen is not fully grown, with many open sutures in the skull that fuse with adulthood.
Ceratosaurus dentisulcatus was named by Madsen and Welles in 1990, based on disarticulated skeleton elements from Utah's Cleveland-Lloyd Dinosaur Quarry in the Brushy Basin Member of the Morrison Formation at Emery County. Each bone has its own catalogue number, but the skeleton as a whole is numbered as UMNH 5278. The name is derived from the Latin "denti" (tooth) and sulcate (furrowed/ploughed), in reference to the persistent, parallel grooves on its teeth.
Ceratosaurus dentisulcatus is significantly larger than other species of
Ceratosaurus and includes remains from the "Camadas de Alcobaça" Formation at Lourinhã on Portugal's west coast. Its horn is unknown.
Ceratosaurus roechlingi was named by Werner Janensch in 1925 for a quadrate bone, a shin, a partial tail vertebrae and other fragments from quarry "Mw" in the upper Saurian Bed of Tendaguru. This specimen stems from an individual almost double the size of
Ceratosaurus magnicornis.
Ceratosaurus roechlingi probably owns the fossils that Janensch named
Labrosaurus (?) stechowi in 1920, but both are considered dubious.
?Ceratosaurus meriani is based on a single tooth found in the Virgulla beds at Malm, near Moutier, Savoy, in the Bern Jura, Switzerland that was originally described and illustrated by Jean-Baptiste Greppin in 1870 as
Megalosaurus meriani. It was renamed
Labrosaurus meriani by Janensch half a century later then tagged
Ceratosaurus sp. (of unknown species) by Madsen and Welles in 1990.
?Ceratosaurus stechowi was originally described in 1920 as a possible species of
Labrosaurus —
Labrosaurus (?) stechowi — by Janensch based on several teeth from Tendaguru. The teeth are
Ceratosaurus-like, but this critter is probably a junior synonym of the equally dubious
Ceratosaurus roechlingi from the same area.
References
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Description géologiques du Jura bernois
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