Proceratosaurus ( proh-sə-RAT-oh-SAW-rəs) is a genus of theropod dinosaur that lived during the Middle Jurassic in what is now England. The holotype and only known specimen consists of a mostly complete skull with an accompanying lower jaw and a hyoid bone, found near Minchinhampton, a town in Gloucestershire. It was originally described in 1910 as a species of Megalosaurus, M. bradleyi, but was moved to its own genus, Proceratosaurus, in 1926. The genus was named for its supposed close relationship with Ceratosaurus, later shown to be erroneous, due to perceived resemblance of Proceratosaurus's incomplete cranial crest to Ceratosaurus's nasal horn. A small to medium-sized dinosaur, the skull of Proceratosaurus is 26.9 cm (10.6 in) long as preserved, and the dinosaur is estimated to have measured around 3 metres (10 ft) in length. The skull is characterised by a number of distinguishing features, including a cranial crest that begins at the junction between the premaxilla and the nasal bone. The teeth are heterodont, having D-shaped teeth at the front of the upper jaw and flattened serrated teeth in the sides of the jaw. Proceratosaurus is considered a coelurosaur, specifically a member of the family Proceratosauridae, and is among the earliest known members of both Coelurosauria and Tyrannosauroidea (the broader group which includes the tyrannosaurids, including the famous Tyrannosaurus), with its complete crest probably being larger than that of Ceratosaurus and more similar to its close relative Guanlong. Proceratosaurus is thought to have been a carnivore, with its diet probably consisting of relatively small prey. The crest was probably used for display. The dinosaur is known from the Great Oolite Group of England, having been found in either the White Limestone Formation or the Forest Marble Formation. During the Bathonian age when Proceratosaurus lived, Britain along with the rest of Western Europe formed a subtropical island archipelago, with southern Britain having a seasonally dry climate. Other dinosaurs known from the Bathonian of Britain include the large theropod Megalosaurus bucklandii, the large sauropod Cetiosaurus, as well as indeterminate stegosaurs, ankylosaurs and heterodontosaurids.
History of discovery In 1910, the British palaeontologist Arthur Smith Woodward reported a partial skull of a theropod dinosaur, discovered some time prior by F. Lewis Bradley during excavation for a reservoir in the vicinity of Minchinhampton, a town in South West England. Bradley had prepared the skull so that the left side was exposed, and submitted it to the Geological Society of London. Woodward made the skull the holotype specimen (the original type specimen with which a species is defined) of a new species of the genus Megalosaurus, naming it M. bradleyi in honour of its discoverer. Megalosaurus, the first named non-bird dinosaur, described in 1824 also based on English fossils, was historically used for any fragmentary remains of large theropods from around the world (wastebasket taxon).
At the time it was discovered, M. bradleyi was one of the most complete theropod skulls known from Europe, possibly with the exception of the crushed and hard to interpret skulls of Compsognathus and Archaeopteryx. Since 1942, the skull has been housed at the Natural History Museum in London, where it is catalogued as specimen NHMUK PV R 4860. The upper part of the skull is missing due to a fissure that had eroded the rock and was partially filled with calcite. While overall well preserved, the skull is somewhat compressed from side-to side compared to what it would have been in life. In a 1923 publication, the German palaeontologist Friedrich von Huene placed the species in the newly coined genus Proceratosaurus, assuming it was an early member of the Ceratosaurus lineage. The name derives from the Greek pro 'before' and the genus name Ceratosaurus. However, the name was invalidly published as it was only used in a diagram in the paper and not mentioned at all in the main text. Von Huene validated the name three years later in two 1926 articles, which contained the required technical description in order for the name to be considered valid. Von Huene considered the crest, as well as the shape of the maxilla (the main tooth bearing upper jaw bone), squamosal (a bone towards the back of the skull), the external nares (bony nostril openings) and the infratemporal fenestra (the skull opening behind the eye socket) as distinctive. Huene regarded the crest, which he thought to represent the base of a nasal horn, as a feature supporting its relationship with Ceratosaurus. While remaining one of the best preserved theropod skulls in Europe, and globally one of the best preserved Middle Jurassic theropod skulls, it subsequently received little scientific attention, mainly being mentioned in studies about general aspects of theropod anatomy and evolution. The skull was re-described by the German palaeontologist Oliver Rauhut and colleagues in 2010, undergoing further mechanical preparation using tools to remove the rock encasing the fossil to reveal additional details of the skull, jaw, and teeth, as well as being CT scanned at the University of Texas during the same year. In 1988, American paleontologist Gregory S. Paul considered the much larger theropod species Piveteausaurus divesensis from the Middle-Late Jurassic of France to belong to Proceratosaurus, coining the new combination Proceratosaurus divesensis. However, later researchers, including Rahut and colleagues in their 2010 redescription, rejected this suggestion, finding the two species to be unrelated.
Description
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