Over time, the three species shifted from tridactyl
to monodactyl distal limb anatomy, with the third metacarpal becoming prominent.
(2015) describe small tridactyl
footprints from a new Lower Cretaceous dinosaur tracksite of La Rioja.
Atreipus acadianus was produced by a habitually quadrupedal tetrapod with a tridactyl
pes and a functionally tetradactyl manus.
The hipparionine horses are with an isolated protCone on maxillary premolar and molar teeth and, as far as known, tridactyl
feet, including genera: Cormohipparion, Neohipparion, Nannippus, Pseudhipparion, Hipparion (North American genus), Hippotherium, Cremohipparion, Hipparion, Sivalhippus, Eurygnathohippus (= senior synonym of Stylohipparion), Proboscidipparion, Plesiohipparion (Wolf et al., 2013).A significant size difference has been noted by many authors in dental and metapodial dimensions between the two supraspecific hipparionine groups of the Siwaliks: Sivalhippus and Cremohipparion (e.g.
On the placentation of the tridactyl
sloth (Bradypus griseus) with a description of the characters of the fetus.
The dinosaur's footprints usually toe slightly inward (slightly negative footprint rotation), as is typical of Comanchean tridactyl
footprints attributed to theropods (Farlow 1987).
Diagnosis: A large hipparion with tridactyl
feet and deep preorbital facial fossa separated from the orbit by a relatively wide preorbital bar, fossa deeply pocketed posteriorly, medially deep and with a well defined continues peripheral border including the anterior rum, cheek teeth complexly ornamented with thickly banded fossette plications and bifid to trifid plicaballins, protocones distinctly flattened lingually and rounded labially, hypoglyphs deeply incised, P2 anterostyle elongate (Colbert, 1935; Ghaffar, 2005).
The photogrammetric images (Falkingham, 2012) were obtained using Agisoft PhotoScan[TM] (version 0.8.5.1423) software (Grupo Aragosaurus, Universidad de Zaragoza License) both for quadruped and tridactyl
tracks with the aim of studying the track morphology through depth maps and contour lines.
DESCRIPTION: Small bipedal, tridactyl
, right theropod pes impression preserved in convex hyporelief, 7 cm long and 4.6 cm wide.
Two parallel tridactyl
trackways are preserved, indicating a direction of movement of 182[degrees].