| Erectopus | |
|---|---|
 | |
| Elements of the holotype specimen (not to scale of each other) | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | †Carnosauria |
| Superfamily: | †Allosauroidea |
| Genus: | †Erectopus von Huene, 1923 |
| Species: | †E. superbus |
| Binomial name | |
| †Erectopus superbus (Sauvage, 1882) [originallyMegalosaurus] | |
| Synonyms | |
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Erectopus (meaning "upright foot") is an extinct genus of basalallosauroidtheropod from theEarly CretaceousLa Penthiève Beds Formation ofFrance and also possibly theCernavodă Formation of southernRomania. The type species isE. superbus, which was initially known as a species ofMegalosaurus.
The holotype, specimen MNHN 2001-4, was discovered during the early 1870s in thephosphate-bearing beds ofLa Penthiève (Mammilatum Zone; lowerAlbian) atLouppy-le-Château in easternFrance,[1] which have also produced remains ofplesiosaurs,ichthyosaurs, andcrocodiles. The fossils originally resided in the private collection of Louis Pierson. The first, two teeth and a vertebra, were first described byCharles Barrois in 1875.[2][3] After more remains had been found, in 1882Henri-Émile Sauvage made them the basis for a newtaxon,Megalosaurus superbus.[4] In 1923, the material was redescribed byFriedrich von Huene, who argued that it could not be included within thegenusMegalosaurus and created for the Pierson theropod a separate genus, naming the speciesErectopus superbus.[5][6] In 1932 von Huene concluded that the original fossils described by Barrois were not necessarily of the same species as the later finds.[7] Assuming that Sauvage had used the former as theholotype ofMegalosaurus superbus, he therefore created another species:Erectopus sauvagei. Von Huene even declined to use the generic nameErectopus for the first species, indicating it as "Gen. indeterm.superbus", which however does not constitute a valid name.[7]
Subsequently, the Pierson collection was dispersed after the death of its owner and the holotype was long believed lost to science afterWorld War II. However, casts of some of the bones have been located in theMuséum National d'Histoire Naturelle (MNHN,Paris), and the anterior part of a leftmaxilla, described by Sauvage in 1882, was found through a Parisianfossil dealer in the late 20th century and purchased by Christian de Muison, apaleontologist at the MNHN.[1] The casts and the incomplete maxilla allowed for a reevaluation ofErectopus byRonan Allain in 2005, which determined that the correcttaxonomic name for the material isE. superbus, as nothing indicated that Sauvage had limited the holotype to the original teeth. The recovered maxilla has been designated alectotype, and the casts of Pierson's specimen has become theplastotype for the taxon. The plastotype includes a partial right manus, the leftfemur, leftcalcaneum, theproximal anddistal halves of the lefttibia, and rightmetatarsal II.[4][5][1] The combined inventory number for thesyntypes is MNHN 2001-4.
A tooth, specimen UAIC (SCM1) 615, discovered sometime between 1900 and 1913 in theCernavodă Formation in Romania was listed as belonging toMegalosaurus (Erectopus)cf. superbus bySimonescu (1913) and later by Csiki-Savaet al. (2016),[8] although it most likely belonged toCarcharodontosauridae.[8]
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Allain (2005) diagnosesErectopus superbus as follows: "Rounded anterior ramus ofmaxilla; slender neck offemur; posterior curvature of proximal half of femur; anterodorsal edge ofcalcaneum dorsally projected; calcaneum twice as long as deep vertically; posteromedial process fortibia on articular surface ofastragalus; length of secondmetatarsal equal to half the length of femur; lateral margin of proximal end of second metatarsal regularly concave."[1]
Allain estimated the weight at 200 kilograms (440 lb).[1] In 2016 it was estimated to be 5 meters (16 ft) in length and 315 kg (694 lbs) in weight.[9]
Based on themorphology of thedistal end of the tibia and the inferred morphology of theastragalus, Allain (2005) placedErectopus superbus within theAllosauroidea[1] (a concept equivalent toCarnosauria, a term some researchers prefer). It is the third youngest carnosaur known from theEuropean Lower Cretaceous, after specimen MM-2-21, the "Montmirat theropod" (Valanginian) of southern France andNeovenator salerii (Barremian) from theIsle of Wight. Carranoet al. (2012) commented thatErectopus may be ametricanthosaurid, but didn't list shared characters.[10]
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