Trachodon marginatus Lambe 1902
Creators: name: Lambe L., M.
Publisher: name: Zenodo
Year: 1902
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Dinosauria
Trachodontidae
Trachodon
Trachodon marginatus

description: Trachodon (Pteropelyx) marginatus. Sp. nov. Plate III, &amp;filig;g. 1, plate IV, figs. 1, 5 and 6, and plates V, VI, VII, VIII, IX and X. Excellently preserved remains, of a large herbivorous dinosaur, met with in abun- dance in the Red Deer river district, arc referred to the above species. Although the various bones of the skeleton were generally found distributed, a number Were discovered associated with each other, the remains of one individual. These consisted of the hunie- Tus, ulna and radius of the left fore limb, a metatarsal and phalanges of the pes, the zygapophyses of cervical vertebrtc, ribs, fragments of teeth, broken ossilied tendons and impressions of the integument. The species is represented further by disassociated femora, tibize, inetacarpals and phalanges of the manus, rami ofthe lower jaw and maxillte with remarkably well preserved teeth in place, dorsal and caudal vertebrtc, a pubic bone, ischia, ilia, chevron bones and numerous teeth as Well as other remains probably referable te the same species. Of the bones, of one individual, found in association, the humerus with the ulna and radius are &amp;filig;gured on plates VI and VII. The humerus, &amp;filig;gs. 1 and 2, has a prominent radial crest that extends, from the external tuberosity above to slightly more than half way down the shaft externally and is roughly striated at its lower end ior the attachment of the deltoid muscle. The head is small and is supported below by a strong rounded ridge. The proximal end, seen from above, is roughly triangular in shape, the front face broadly excavated with conspicuously concave surfaces on either side of the head behind that continue forward to meet the inner and outer‘ tuberosities. The condyles are separated by a deep depression behind, that extends up the shaft for a short distance; in front they are not so conspicuously divided. An archaic feature is expressed in the great downward extension and conspicuous singularity of the radial crest. In comparing this humerus with that of Hadrosaurus Foulkii, * Leidy, from the Cretaceous of the east, a form allied to this species, a marked difference is noticeable in their proportions. [table omitted] * 1 SG5. Cretaceous Reptiles of the United States, p. 7 G, pl. xiv, &amp;filig;gs. 1, ‘l, 3 and 4. Smithsonian Contr. to Knowledge, vol. xiv. The ulna and radius, belonging to the same fore limb as the humerus, are &amp;filig;gured as they Were found, The ulna has a strongly developed olecranon process terminating its expanded proximal end which is concave on three sides so as to be subtriangular in section. From the middle ofits shaft downward, it increases in size very little. The radius is a comparatively slender" bone but terminates below in a carpal articu- lating surface slightly larger than that of the distal end of the ulna. [table omitted] The right femur, plate VIII, provisionally associated with T marginatus, is interesting in many particulars, notably, its slenderness, the prominence of the head, the backward extension of the condyles and the marked development of the third trochanter. The inner condyle is larger than the outer one,‘ they are both, viewed from the side, broadly rounded posteriorly and pointed in front. From the great trochanter, a prominent ridge extends dowrrward, for some distance on the outer front face of the bone. [table omitted] A comparison of this femur with that of Hadrosaurus foulkii, Leidy reveals a great similarity in their general proportions. If anything, the Red Deer‘ river‘ specimen is more slender but otherwise there are no very marked differences. The tibia (plate IX, &amp;filig;gs. 1 and 2), Was probably not as long as the femur‘ but was a decidedly robust bone. Unfortunately no specimens were secured associated With femora that might be supposed to belong' to the same individual. Of the two right tibiae &amp;filig;gured on plate IX (provisionally referred to T. rnarginatus), the one on the right, seen fr‘orn behind, is considerably crushed so as to exaggerate the breadth of the proximal end; the other specimen is remarkably Well preserved. This bone of the leg, cylindrical at mid-length, expands rapidly toward either‘ end. The longer axis of the distal end is nearly at right angles to that of the proximal end. Viewed from behind, the proximal end is seen to be broadly concave, the outer‘ side consisting of a backwardly directed &amp;fllig;ange. On the inner side the head is divided into two parts by a deep furrow. [table omitted] Ramus of lower jaw, plates III and IV, long and narrow, with teeth occupying a deep, narrow chamber or magazine in the posteriortwo-thirds of the length. Cororroid process high, rising abruptly from the outer‘ side, of the posterior end; laterally compressed above, deeply excavated below posteriorly. An edentulous prolongation in front curves obliquely downward and inward with a symphyseal surface at the: inner forward end. Upper and lower borders nearly parallel. Outer wall of dental chamber thick and strong, with shallow, vertical, alveolar‘ grooves occupying its inner side. Inner‘ wall,.very thin, averaging about 2 mrn. in thickness, Without alveolar‘ grooves proper; seldom preserved. Coronoid process below, produced backward externally as a thin plate of bone continuous With the outer surface of the jaw; on its inner‘ side it unites with the outer‘ alveolar‘ wall in advance of the posterior end of the dental chamber. Derrtary canal leading from the upper‘ part of the posterior cavity forward between the outer‘ surface of the jaw and the dental chamber‘. Mandibular groove passing forward under the lower‘ border‘ of the chamber‘. A row of foramina occurs on the inner side, one foramen at the base of each vertical series of teeth. A number of foramina also present on the outer‘ suface. Teeth replaced from within, their keeled, erranrelled surfaces of the crown inside occurring in a vertical series of three or four near the middle of the jaw with two or three ofa series in use in the grinding surface at the same time. Their lateral margins decorated with small, rounded projections fr‘om near the apex downward to where the crown begins to narrow again. [table omitted] [table omitted] Maxilla, plate V, robust, high at the centre, sloping downward toward either end, the dental chamber occupying nearly the whole of its length. Seen from above, the posterior half slopes obliquely forward and outward, while the reverse is the case in front; at the extreme anterior end there is a limited slope inclined obliquely outward. Also, viewed irom above, the posterior half is straight and broader than the front half which narrows to a- rounded, outwardly turned point. Inner surface rather flat. Outer surface with a rounded ridge running horizontally from the posterior end to meet the facet for the articulation of the anterior end of the jugal. On the inner, upper side behind mid-length, a facet, probably for the palatine, is present. Teeth replacing each other from the inner side, apparently not more than two, of a series in v;se in the grinding surface at the same time; the carinated, enamelled faces of the crowns facing outward. A row of foramina, similar to that of the lower jaw, conspicious in the upper part of the inner side. Several large foramina occur in the anterior half of the outer side. [table omitted] Pubis, plate X, fig. 1 (provisionally associated with T.marginatus), produced forward into a broad, thin, transversely compressed, spatulate expansion that is slightly concave on its outer surface. Posteriorly a slender postpubic process, springing from a point inside and in advance of the base of the pedestal bearing the ischiac facet, is directed backward on the lower border of the ischium with which it effects a ligamental union. Iliac facet small, separated from the isehiac facet by a wide, concave, acetabular emargination that forms about one-third of the whole acetabular‘ border. [table omitted] Isehium long, plate X, &amp;filig;g. 2 (provisionally associated with T. marginatus), laterally compressed, broadly expanded proximally and ending distally in a loot-shaped extremity pointing downward. Shaft almost straight, its upper‘ edge curving concavely and broadly upward to meet the iliac facet Upper expanded part very thin, plate-like, thickened abruptly, on either side of the thin, concave edge of the acetabular border, to form well developed iliac and pubic facets. The surfaces of the facets very rugose. A narrow postpubic facet extends, downward and backward at right angles to the pubic facet along the lower front border of the proximal end. Below this facet and separated from it by a concavity in the thin margin is a flange of bone for the further support of the postpubis. Inner surface of distal half, striated longitudinally for a ligamental union with its mate of the opposite side. [table omitted] A number of ilia, representing di&amp;filig;erent types of herbivorous dinosaurs, are included in the collections. In &amp;filig;g. 23, three of these are shown. The upper one, A, is of the Monoclonius type and is arbitrarily associated with. dawsoni. another, B, is referred to Trachodon marginatus (provisionally), Whilst the lower one; C, Stegosauroid in its character, may belong to Stereocepltalus tutus.
description: Published as part of <i>Lambe L. M., 1902, New genera and species from the Belly River Series (mid-Cretaceous), pp. 25-81 in Geological Survey of Canada Contributions to Canadian Palaeontology 3</i> on pages 71-75, DOI: 10.5281/zenodo.3233762