Heterodontosaurus, CROMPTON & CHARIG, 1962

Norman, David B., Crompton, Alfred W., Butler, Richard J., Porro, Laura B. & Charig, Alan J., 2011, The Lower Jurassic ornithischian dinosaur Heterodontosaurus tucki Crompton & Charig, 1962: cranial anatomy, functional morphology, taxonomy, and relationships, Zoological Journal of the Linnean Society 163, pp. 182-276: 187-192

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Generic diagnosis: As for species (below)

Type species: H. tucki Crompton & Charig, 1962  


Lycorhinus tucki (Crompton & Charig) Thulborn, 1970a: 244   .

Lycorhinus tucki (Crompton & Charig) Thulborn, 1974: 161   .

Generic and specific characteristics

General: Basal ornithischian dinosaur, known stratigraphical range: Sinemurian/Pliensbachian.

Cranial (*indicates autapomorphy – see also discussion in Phylogenetic Relationships section): Deep buccal emargination is formed by a strongly dorsoventrally compressed and transversely expanded maxillary ridge, which forms the ventral margin of the external antorbital fenestra and is thickened along its lateral margin*; antorbital fossa extends posteriorly to form a channel on the external surface of the jugal*; quadratojugal forms a thin wing that overlaps the entire external surface of the quadrate (contacting the squamosal dorsally and terminating ventrally just above the articular condyle) and contacts the jugal via a narrow bridge of bone*; quadratojugal has a constricted scarf suture with the jugal*; narrow and obliquely orientated ventral jugal projection closely aligned against the lateral surface of the lower jaw*; prominent laterally expanded ‘boss’ on the jugal*; sharply defined curved ridge on the external surface of the postorbital that is continuous with a similar ledge on the dorsolateral margin of the squamosal*; remnants of intracranial pneumatism preserved as pits on the paroccipital process and quadrate, and as sinuses on the jugal boss and anteromedial process of the maxilla*; narrow and deep pterygoid flanges lie close to the medial surface of the lower jaw (forming a slot-like guide with the ventral process of the jugal)*; paroccipital wings perforated by a discrete vascular/neural canal*; basisphenoid flanges are large, oblique and extend medial to the pterygoids and enclose narrow fossae on either side of the ventral midline of the braincase; surangular develops two finger-like rami that form much of the dorsal margin of the coronoid eminence anterior to the jaw joint*; elongate, slot-shaped surangular foramen*; broad depression on the lateral surface of the angular*.

Dentition (*indicates autapomorphy): Premaxillary and dentary caniniforms have fine, blunt, serrations (six per mm) running down their posterior margins; premaxillary caniniform lacks serrations along its anterior edge; dentary caniniform has widely spaced, rounded denticulations running down the upper portion of its anterior edge*; columnar maxillary and dentary teeth have crowns that are only slightly expanded either anteroposteriorly or transversely above the root (the ‘cingulum’ and ‘neck’ at the crownroot junction are completely absent)*; labial surface of maxillary crowns possess three prominent ridges that separate equal-sized, clearly defined excavated regions*; lingual surface of dentary crowns display a mesially offset principal ridge and crown margins that create subequal adjacent crown areas*; extensive wear facets on the upper and lower dentitions display a warp because successive teeth are worn at differing angles*.

Postcranial characters (*indicates autapomorphy – see also discussion in Phylogenetic Relationships section): (derived from Santa Luca, 1980 – with additions and modifications) axial vertebral column: 21 vertebrae (9 cervical, 12 dorsal)*, sacrum: 6 fused vertebrae*, caudal vertebrae: 34+; prominent epipophyses present on anterior cervical postzygapophyses*, ossified tendons distributed across the neural spines of dorsal and sacral vertebrae only; scapular blade narrow and elongate with expanded distal (extrascapular) portion; humerus with a large deltopectoral crest and large entepicondyle*; humerus lacks a posterior (olecranon) fossa; ulna with prominent olecranon; manus length more than 40% of the combined length of humerus and radius; nine carpal bones; manus digits 1–3 parallel, digits 4–5 reduced in size and divergent; penultimate phalanges of digits 2 and 3 more elongated than the proximal phalanges; extensor pits present on the dorsal surface of distal end metacarpals and phalanges; manual unguals strongly recurved, and with prominent flexor tubercles. Ilium, with a narrow vertical facet on the ischial peduncle that resembles an avian antitrochanter*; prepubic process short and deep, postpubis as long as ischium; obturator process absent; ischial shaft marked by an elongate lateral ridge that is drawn out to form a prominent lateral shelf along the mid-section of the shaft*; femoral greater and anterior trochanters not separated by a cleft; transverse axis of distal femoral articular surface obliquely orientated; fibula reduced and fused to tibia distally*; astragalus and calcaneum fused*; astragalocalcaneum fused to the distal ends of tibia and fibula*; three distal tarsals present but fused to proximal ends of their metatarsals*; metatarsals 1–4 fused together*.



SAM-PK-K337 – Iziko South African Museum, Cape Town ( Figs 1–3 View Figure 1 View Figure 2 View Figure 3 , 7 View Figure 7 , 20–22 View Figure 20 View Figure 21 View Figure 22 and Appendix 3); see also Crompton & Charig, 1962: fig. 1; Charig & Crompton, 1974: figs 10, 11; Galton, 1986: fig. 16.6r,s; Báez & Marsicano, 2001: fig. 5C). Nearly complete skull and lower jaw embedded in greyish-yellow sandstone. The surface of the skull is encrusted by an adherent, and very tough, layer of haematite that has been removed partially using a small diamond saw. Most of the preparation was carried out by Arthur E. Rixon, formerly in charge of the Palaeontological Laboratory of the British Museum (Natural History); one of the authors (A. W. C.) continued preparation as far as seemed prudent at the time. Postcranial remains were also listed by Crompton & Charig (1962: 1075) but the whereabouts of this potentially extremely important material is currently unknown.

During fossilization the specimen has been compressed laterally. The skull roof slopes steeply toward the right (at an angle of about 35° from the horizontal, the latter being taken as normal to the sagittal plane – see Fig. 7 View Figure 7 ). Structures on the right side have been displaced ventrad and a little backwards with respect to those in the mid-line. The skull is nevertheless reasonably well preserved on the right side ( Fig. 1 View Figure 1 , Appendix 3A). A short section of the dentary ramus, just behind the dentary– predentary contact, is missing. On the left side the superficial bones of the skull have largely been eroded away, revealing parts of the palate and braincase; the only trace of the left lower jaw is the anterior tip of the dentary and adjacent predentary ( Fig. 2 View Figure 2 , Appendix 3B).

Provenance: 1890 m above sea-level on the mountain behind Tyindini trading store, Herschel District, Eastern Cape Province, Republic of South Africa (30°32′S, 27°32′E; Kitching & Raath, 1984: table 1). Discovered by A. W. C. during the 1961/1962 joint British/South African expedition to the Upper Triassic outcrops in South Africa and Basutoland (= Lesotho). Stratigraphical occurrence: Clarens Formation (formerly ‘Cave Sandstone’, Stormberg Series): Hettangian-Sinemurian ( Olsen & Galton, 1984), Pliensbachian-Toarcian ( Yates et al., 2004). The most probable age for the Clarens Formation: latest Sinemurian-Pliensbachian ( Jourdan et al., 2005, 2007, 2008).

Referred specimens


Articulated skull, lower jaw ( Figs 4–7, 16–18 View Figure 16 View Figure 17 View Figure 18 , 23–27 View Figure 23 View Figure 24 View Figure 25 View Figure 26 View Figure 27 and Appendices 4–6; see also Santa Luca et al., 1976: fig. 1; Santa Luca, 1980: figs 1, 2; Weishampel & Witmer, 1990: fig. 23.4; Norman et al., 2004c: fig. 18.10A), and postcranial skeleton ( Santa Luca et al., 1976: fig. 1; Santa Luca, 1980: figs 1, 3–22). Preparation of this skull was undertaken by Mrs Ione Rudner at the Iziko South African Museum, Cape Town. A considerable number of minor breaks (probably having their origin in post-mortem deformation, as well as some caused by the mechanical preparation and by later mishandling) have been repaired by adhesive; additionally, a moderate-to-thick layer of adhesive-consolidant has been applied to the surfaces of bones and teeth, which obscures finer anatomical details (consolidant on the occlusal surfaces of the teeth has since been removed by L. B. P.). A detailed photographic record (including stereo-pair images) made at the time of the original preparation for A. W. C. has been archived at the Sedgwick Museum, Cambridge, UK.

The specimen was preserved in red sandstone. The skull (as with the holotype) has suffered lateral crushing and displacement; however, it is more complete and its preservation overall is better than that of the holotype. Unlike the holotype, the skull was not covered in a layer of haematite.

Provenance: At an altitude of about 1770 m on the northern slopes of Kromspruit (alternative spelling Krommespruit) Mountain, Voyizane (= ‘Voisana’; 30°34′S, 27°26′E; Kitching & Raath, 1984: table 1), Herschel District , Eastern Cape Province, South Africa GoogleMaps   .

Discovered by A. W. C. on the 1966–67 joint South African Museum, Yale University, British Museum (Natural History), University of London expedition to the ‘Red Beds’ of South Africa and southern Lesotho ( Attridge & Charig, 1967; Crompton, 1968).

Stratigraphical occurrence: From the upper part of the Elliot Formation (formerly ‘upper Red Beds’), Stormberg Series; probably of Early Jurassic age (stratigraphically lower than the horizon at which the holotype was found): Hettangian-Sinemurian ( Olsen & Galton, 1984) or Pliensbachian-Toarcian ( Yates et al., 2004). The most probable age for the upper part of the Elliot Formation is upper Sinemurian (R. Irmis pers. comm. 2010).


Partial left maxilla containing seven erupted crowns and three replacement crowns, with attached fragments of the jugal and lacrimal bones ( Figs 30–33 View Figure 30 View Figure 31 View Figure 32 View Figure 33 ).

Provenance: Site 18a, Voisana, Kromspruit 9 Farm, Herschel District , Eastern Cape Province, South Africa (30°34′S, 27°26′E; Kitching & Raath, 1984). Collected on the 1966–67 expedition of the South African Museum , Yale University, British Museum (Natural History) and University of London. Reports and letters exchanged between A. J. C. and A. W. C. suggest that it was recovered from the same locality (Voyizane/Voisana) in Herschel District that yielded the complete, articulated heterodontosaur skeleton (SAM-PK-K1332) and several other specimens GoogleMaps   .

Stratigraphical occurrence: Upper Elliot Formation (as above).


Partial skull ( Figs 28 View Figure 28 , 29 View Figure 29 ; see also Butler et al., 2008a: figs 1–3, 4B, 5) of a demonstrably ontogenetically immature specimen.

Provenance: Kromspruit area, Herschel District, Eastern Cape Province, South Africa.

Stratigraphical occurrence: Probably upper Elliot Formation.

Specimens provisionally referred to Heterodontosaurus sp.   pending further study

NMQR 1788: Partial skull, undetermined stratigraphical horizon, Tushielaw, Barkly East, Eastern Cape Province, South Africa (L. B. Porro et al., in press).

SAM-PK-K10488: Partial lower jaw with evidence of replacement crowns, and fragments of upper jaw. Upper Elliot Formation, Eastern Cape Province. (L. B. Porro, unpubl. data).













Norman, David B., Crompton, Alfred W., Butler, Richard J., Porro, Laura B. & Charig, Alan J. 2011

Lycorhinus tucki (Crompton & Charig)

Thulborn RA 1974: 161

Lycorhinus tucki (Crompton & Charig)

Thulborn RA 1970: 244