• 
  
• Elaphrosaurus iguidiensis, was described by Lapparent in 1960, and the material was collected in Algeria, Libya and Niger in Early Cretaceous sediments. The material consists of over 40 teeth, a manual ungual, eight caudal vertebrae, a distal femur fragment, and a complete tibia measuring 350 mm. These specimens originated in three different localities and do not appear to belong to the same species.
  
• Elaphrosaurus gautieri, was first described by Lapparent in 1960, and the material was collected at the Tiouraren Formation in Niger in Middle-Late Jurassic sediments. This material, a complete neck vertebra, has since been renamed Spinostropheus gautieri by Sereno et al. (2004).
  
• Elaphrosaurus philtippettensis, was erected by Pickering in 1995 based on USNM 5737, which consists of a tibia, a humerus, some metatarsals, and the distal portion of a fragmentary pubic bones recovered from the Morrison Formation of Colorado. Further research by Carpenter et al. (2005) suggested that the fossils are not ceratosaurian and are likely referable to the coelurid theropod Tanycolagreus.
  
• Elaphrosaurus agilis, was described Dale Russel in 1972, based on a pair of fused pubic bones that O.C. Marsh had earlier named Coelurus agilis, believing that this specimen represented a much larger version of the type specimen, Coelurus fragilis. John Ostrom (1980) confirmed Charles Gilmore's earlier position that Coelurus agilis was synonymous with Coelurus fragilis. This means that Elaphrosaurus agilis is actually the same animal as Coelurus fragilis.
  
• Elaphrosaurus sp. USNM 8415, was discovered in 1883 and first referred to the ornithopod Dryosaurus. It was later referred to Elaphrosaurus by Galton in 1982, based on remains recovered at the Morrison Formation of Colorado. This material, which is clearly ceratosaurian, does not bare any morphology that specifically ties it to Elaphrosaurus. Current knowledge limits the placement of this material to Ceratosauria incertae sedis.
  
• Elaphrosaurus sp. DMNH 36284, was referred to this genus by Chure in 2001, based on the proximal portion of a fragmentary tibia also from the Morrison Formation. Phylogenetic analysis by Carrano and Sampson (2008) showed that was not ceratosaurian, but instead resembled the leg bone of an abelisauroid theropod that has yet to be formally described.

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• the cervical vertebrae possess thin latero-ventral laminae, bordering the posterior pleurocoel ventrally
  
• the cervical vertebrae are strongly concave ventrally, with the ventral margin arching above the mid-height of the anterior articular facet at its highest point
  
• the brevis fossa of the ilium is extremely widened, so that the brevis shelf forms an almost horizontal lateral flange
  
• the distal end of the ischium is strongly expanded into a triangular boot

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Given the incompleteness of the skeleton, the
length of Elaphrosaurus cannot be measured; how-
ever, reconstructing the missing elements of the ver-
tebral column, and assuming some 45 caudal
vertebrae, Janensch’s (1929) estimate of ~580 cm for
the total length of the vertebral column seems very
reasonable. As no elements of the skull are pre-
served, its length can only be guessed. In the basal
ceratosaur Ceratosaurus, the skull is approximately
as long as the femur (Gilmore, 1920), but in Limu-
saurus, probably a closer relative of Elaphrosaurus
(see below), the skull length is about half that of the
femur (Xu et al., 2009). Furthermore, the strongly
elongate cervical vertebrae with poorly developed
processes (neural spine and epipophyses) indicate
that the skull of Elaphrosaurus was light and thus
probably relatively small. Nevertheless, taking the
above values as limits for estimating skull size,the cranium
of this taxon was probably 25–50 cm long,
resulting in a total body length of 6.0–6.3 cm. This
body length is somewhat larger than that estimated
for the type specimens of Ceratosaurus (5.33–5.90 m)
and Dilophosaurus (5.07–6.05 m; Gilmore, 1920;
Welles, 1984; Paul, 1988; Therrien & Henderson,
2007). The femoral length of Elaphrosaurus
(529 mm) might seem to contradict this estimate, as
both Ceratosaurus and Dilophosaurus have longer
femora (620 and 557 mm, respectively; Gilmore,
1920; Welles, 1984), but this simply reflects different
limb proportions, as the entire hindlimb (measured
as femoral length +tibia length +length of metatar-
sus III) is longer in the former genus than in the lat-
ter taxa (1528 versus 1429, and 1412 mm,
respectively).

Also of interest is the body mass of Elaphrosaurus.
The only published estimates are those of Paul
(1988; 210 kg) and Christiansen & Fari~
na (2004;
245 kg), who used femur length and scaled volumet-
ric analysis, respectively. We estimated the body
mass of Elaphrosaurus on the basis of femoral cir-
cumference, using the formula of Campione et al.
(2014). The minimum circumference of 177 mm
occurs in the proximal part of the femur, just proxi-
mal to the cleft that separates the lesser trochanter
from the shaft, whereas the midshaft circumference
is 193 mm. These two measurements provide body
mass estimates of 322 and 409 kg, respectively. Com-
parisons with the body masses of the probably
slightly shorter Ceratosaurus (586 kg; USNM 4734)
and Dilophosaurus (330 kg; UCMP V.37302) underli-
nes the slender build of Elaphrosaurus.

The hindlimb proportions of Elaphrosaurus are
noteworthy. Most medium-sized theropods (4–7m
body length) tend towards limb proportions of an ‘in-
termediate’ nature, with proportionally short meta-
tarsals relative to the femur (Carrano, 1999). In
Elaphrosaurus, however, the metatarsals are 74% of
the femoral length. Among theropods with a body
mass of more than 100 kg, similar metatarsal pro-
portions are only found in some ornithomimosaurs
[e.g. metatarsal length is 77% of femoral length in
Struthiomimus altus (Lambe, 1902); Osborn, 1916].
Indeed, Elaphrosaurus exhibits some of the most
cursorial limb proportions known among dinosaurs;
in addition, the fourth trochanter is placed quite
proximally on the femoral shaft. Whether this indi-
cates especially rapid locomotion, or instead a wide-
ranging life habit, cannot yet be tested (Carrano,
1999).

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It had legs very well adapted for running,in spite of the elongate body proportions.

Ausar

Jan 3 2017, 01:22 AM

Quote:

 

It had legs very well adapted for running,in spite of the elongate body proportions.

Eh, "in spite"?

cat loves food

Carnotaur

Jan 3 2017, 01:40 AM

Ausar

Jan 3 2017, 01:22 AM

Quote:

 

It had legs very well adapted for running,in spite of the elongate body proportions.

Eh, "in spite"?

cat loves food

Its because I would expect cursorial bipeds to have a compact body plan,in order to help decreasing the rotational inertia.