Heishanlestes changi, HU & FOX & WANG & LI, 2005

HU, YAO-MING, FOX, RICHARD C., WANG, YUAN-QING & LI, CHUAN-KUI, 2005, A New Spalacotheriid Symmetrodont from the Early Cretaceous of Northeastern China, American Museum Novitates 3475 (1), pp. 1-20 : 4

Heishanlestes changi , new species

Figures 1–5 , table 1

HOLOTYPE: IVPP V 7480 , a nearly complete right dentary containing p1–4, m1–6 (figs. 1, 3, 4, 5).

REFERRED SPECIMENS: IVPP V 7481, anterior part of a left dentary containing an erupting canine, p1–4, m1 (figs. 2, 3); IVPP V 7482, anterior part of a left dentary containing p4, m1, and alveolus for p3 (fig. 2).

ETYMOLOGY: ‘‘changi’’ is for Professor Zhenglu Chang, from Liaoning Technical University, for his important contribution to the study of Mesozoic stratigraphy and paleontology of northeastern China during the past 50 years.

DIAGNOSIS: Dental formula: ci, p1–4, m1– 6, differing from Spalacotherium tricuspidens and Spalacolestes cretulablatta , which have seven lower molars; premolars tightly spaced and overlapping; m1 with obtuse trigonid angle; m5–6 reduced in size and with a subcylindrical cusp arising from the center of the trigonid; differing from Zhangheotherium and Maotherium in having a strong pterygoid crest but absence of an enlarged first incisor, absence of a Meckelian groove, and reduction of cingular cusps on lower molars.

LOCALITY: Badaohao, Heishan County, Liaoning Province, China (coordinates: 418509N and 1218559E).

GEOLOGIC OCCURRENCE: Shahai Formation.

AGE: Aptian, Early Cretaceous.

Figures

Fig. 1. Stereoscopic views of the right dentary and cheek teeth of Heishanlestes changi (IVPP V 7480, holotype). A, lateral view; B, crown view; C, medial view. Arrow in B indicates the pocket behind the pterygoid crest. Scale bar is 5 mm.

Fig. 2. Stereoscopic views of anterior parts of the left dentaries and anterior cheek teeth of Heishanlestes changi. A, lateral; B, crown; and C, medial views of IVPP V 7481 (with c1–m1). D, lateral; E, crown; and F, medial views of IVPP V 7482 (with p4 and m1). Arrows in A indicate mental foramina. Scale bar is 2 mm.

Fig. 3. SEM images of dentaries and anterior cheek teeth of Heishanlestes changi (from casts). A, laterodorsal; B, mediodorsal; and C, crown views of IVPP V 7481. D, crown view of ci and m1 of IVPP V 7480. Scale bar is for A–D. c1, canine; ed, edge of canine alveolus; m1, first molar; p1–p4, premolars; arrows in A and D indicate wear facet.

Fig. 4. SEM images of lower molars of Heishanlestes changi (cast of IVPP V 7480). A, lateral view; B, crown view. prd, protoconid; pad, paraconid; med, metaconid; dcc, distal cingular cusp; mcc, mesial cingular cusp; m1–m6, molars; *, large cusp in the middle of trigonid; arrows indicate anterior and posterior wear facets on m1.

Fig. 5. SEM images of the right dentary of Heishanlestes changi (cast of IVPP V 7480). A, lateral view of the condylar process and the adjacent area; B, lateral view of the posterior part of the dentary; C, medial view of the posterior part of the dentary. Arrows in A indicate the small sulcus; arrows in B indicate the edge of the masseteric shelf; arrow 1, small depression at the root of the coronoid process; arrow 2, the depression anteroventral to the mandibular foramen; arrows 3, edge of the pterygoid crest; arrow 4, position of the mandibular foramen. Scale bars are 500 mm.