The vertebrae of the tail were high-spined, though not as high as those of its relative Montanoceratops, and the pectoral and pelvis girdle bones were slender and more like earlier ceratopsians.

The teeth of Leptoceratops are unique among dinosaurs, showing tooth wear in a fashion that must have been driven by mammal-like rotation of the jaw while chewing.

This, along with the handling of stress in the jaws, show that Leptoceratops had an efficient bite allowing it to be adaptable to different food types, such as the angiosperms, conifers, or cycads found in its environment.

The climate was cool in the foothills of the mountainous cordillera, but the range of Leptoceratops also extended into coastal plains where it lived alongside much larger herbivorous dinosaurs.

Leptoceratops was not a common component of the dinosaur fauna, but coexisted with the herbivorous Ankylosaurus, Edmontosaurus, Pachycephalosaurus, Triceratops and Thescelosaurus among other ornithischians, and theropods including dromaeosaurids, troodontids, Ornithomimus, Elmisaurus, an alvarezsaurid and Tyrannosaurus.

A 1910 expedition by the American Museum of Natural History (AMNH) discovered two ceratopsian specimens from the Maastrichtian age of the Cretaceous along the Red Deer River in Alberta, Canada.

One of these individuals preserves a partial skull and was designated as the holotype of the new taxon Leptoceratops gracilis when it was described in 1914 by American palaeontologist Barnum Brown.

Within the Scollard Formation, Leptoceratops was known in 2013 from nine specimens found in the lower portion, with an estimated range of 65.5-66.1 million years old (0.5 my older with recalibration).

The material, which is fragmentary but clearly similar to other Leptoceratops remains, also included a complete foot for the first time, along with other elements not represented in other specimens.

This specimen, Princeton University (now Yale Peabody Museum) number 18133, preserves a nearly complete hindlimb, pelvis, and tail alongside some isolated teeth.

[11][12] The assignment of YPM VPPU 018133 to Leptoceratops was questioned by Chinnery in 2004, as the jugal is similar to that described for Prenoceratops and the locality may be part of the Meeteetse Formation instead.

by Michael J. Ryan and Currie in 1998 despite being substantially older than other Leptoceratops material then known, as the only other North American protoceratopsian named, Montanoceratops, showed clear differences in anatomy from the Dinosaur Park specimen.

[15] Leptoceratops was an unusual early ceratopsian, displaying a very large head but minimal frill, a more forwards center of mass suggesting quadrupedality, and a higher number of vertebrae in front of the pelvis.

This is similar in size to some other early ceratopsians like Cerasinops, Zhuchengceratops, Prenoceratops, Montanoceratops and Protoceratops, but smaller than the large Udanoceratops which was around 4 m (13 ft) long and 700 kg (1,500 lb).

The parietal bones of the rear skull, which in Protoceratops are elongated to form a frill and bear fenestrae, are reduced and solid in Leptoceratops.

[4] The anatomy of the braincase of Leptoceratops is similar to that of Montanoceratops with minor differences, including a restricted neck to the occipital condyle, an unsplit ridge on the supraoccipital, and an elevated articulation for the palate on the exoccipital.

[4] When articulated, the mandibles of Leptoceratops are similar to other basal neoceratopsians in being very wide with a lowered articular surface for the skull, reflective of different feeding adaptations during the evolution of ceratopsians where the closing of the jaws brings all the teeth into contact at the same time.

[17] The teeth in Leptoceratops are some of the most distinct in Ceratopsia, showing a unique type of tooth-on-tooth wear only shared with taxa such as Udanoceratops and Archaeoceratops.

[4][18] The unworn surface of teeth of Leptoceratops shows a strong ridge down along the crown, which is slightly offset from central and often follows a curved path.

The scapula is more slender than in ceratopsids but similar to Protoceratops while lacking the ridge that extends diagonally across the scapular blade found in the other genera.

[20][21][22] A similar classification was supported by American palaeontologist Alfred Romer, who placed Leptoceratops within the new family Leptoceratopsidae in 1927, which, together with Ceratopsidae and Protoceratopsidae, formed the group Ceratopsia.

[24] American palaeontologist Paul C. Sereno suggested in 1986 that Protoceratopsidae as traditionally used is paraphyletic, instead forming a successive acquisition of features closer to Ceratopsidae.

[34][35] Helioceratops brachygnathus Leptoceratops gracilis Ischioceratops zhuchengensis Prenoceratops pieganensis Udanoceratops tchizhovi Zhuchengceratops inexpectus Koreaceratops hwaseongensis Montanoceratops cerorhynchus Cerasinops hodgskissi Gryphoceratops morrisoni Unescoceratops kopelhusae The early evolution of ceratopsians saw a transition from the primitive bipedality to quadrupedality.

The forelimb would be held upright with the elbow flexed and the thumb and second finger pointing forwards while the other digits splayed to the side, although a more lateral sprawl was possible.

[36] Scratch-digging is also believed to have been possible in Leptoceratops based on its forelimb anatomy,[36] which is supported by fossils from the Hell Creek Formation suggesting burrowing.

[41] Biomechanical studies of the jaws of ceratopsians have also identified that Leptoceratops, as well as other leptoceratopsids, had efficient bites allowing them to be adaptable to different food types, not simply showing improvements along the evolution of ceratopsids.

The sediments of these regions were alluvial plain and foothill, with the Leptoceratops fauna consequently inhabiting cool environments flanking the mountainous cordillera.

[46][47][48] While slightly older floras were codominated by cycad-palm-fern meadows, by the time of the Hell Creek angiosperms were dominant in a forested landscape of small trees.

Mammals are also very diverse, with multituberculates, deltatheridiids, the marsupials Alphadon, Pediomys, Didelphodon and Eodelphis, and the insectivorans Gypsonictops, Cimolestes and Batodon.

[48] Within the Hell Creek Formation of Montana, Leptoceratops lived alongside the dinosaurs including Thescelosaurus, pachycephalosaurids Pachycephalosaurus, Stygimoloch and Sphaerotholus, the hadrosaurid Edmontosaurus and possibly Parasaurolophus, ceratopsians like Triceratops and Torosaurus, the nodosaurid Edmontonia and ankylosaurid Ankylosaurus, multiple dromaeosaurids and troodontids, the ornithomimid Ornithomimus, the caenagnathid Elmisaurus, tyrannosaurids including Tyrannosaurus, an alvarezsaurid, and the bird Avisaurus.