Placodus gigas Agassiz, 1833

Sues, Hans-Dieter & Schoch, Rainer R., 2025, Synopsis of the Triassic reptiles from Germany, Fossil Record 28 (2), pp. 411-483 : 411-483

Placodus gigas Agassiz, 1833

Holotype.

SNSB-BSPG AS VII 1208 , partial skull (Fig. 6 A, B ).

Type locality.

Ochsenberg near Laineck (also known as Lainecker Berg or Lainecker Höhenzug), east of Bayreuth, Bavaria.

Type horizon.

Ceratites flexuosus through C. compressus Zones , upper part of Trochitenkalk Formation and lower part of Meissner Formation, Upper Muschelkalk Subgroup. Age: Middle Triassic (Anisian: Illyrian). Geyer and Friedlein (2020) considered the Muschelkalk deposits exposed in the region of the Lainecker Höhenzug a distinct unit of marginal marine strata, which they refer to as Eschenbach Formation. They named the subformation that has yielded the holotypes of Placodus gigas and several other taxa of Muschelkalk reptiles (see below) Eschenbach Formation 5.

Referred material.

See Rieppel (1995). A particularly important specimen of Placodus gigas ( SMF R 1035) preserves an incomplete skull and much of the postcranial skeleton ( Drevermann 1933).

Diagnosis.

Distinguished by the following combination of features: Rostrum spatulate; three enlarged, strongly procumbent premaxillary teeth separated from maxillary teeth by diastema; three transversally expanded palatine tooth plates; nasals, frontals, and parietals fused in adults; jugal extending anteriorly beyond level of anterior orbital margin; prefrontal and postfrontal in contact dorsal to orbit; pterygoid restricted to posterior position on dermal palate; basioccipital tubera in complex ventral relation to dermal palate; ‘ alisphenoid bridge’ underlying olfactory tracts; coronoid process of dentary large; lateral exposure of coronoid bone restricted; mandibular symphysis elongate, formed by dentaries and splenials; neural arches of dorsal vertebrae with elongate transverse processes and hyposphene-hypantrum accessory articulations; neural canal high dorsoventrally and rectangular in cross-section; coracoid small; thyroid fenestra restricted; and humerus expanded distally, without entepicondylar foramen absent ( Rieppel 1995).

Comments.

Following the systematic revision by Rieppel (1995), Placodus is now restricted to the type-species Placodus gigas . Rieppel also synonymized Anomosaurus strunzi F. Huene, 1905 c , based on vertebrae from various Muschelkalk strata and localities, with Placodus gigas . F. Huene (1902) already used the generic nomen Anomosaurus without a species name.

References.

Agassiz (1833), F. Huene (1902, 1905 c, 1933), Broili (1912), Edinger (1925), Drevermann (1933), Rieppel (1995), Nosotti and Rieppel (2002), Neenan et al. (2014).

Figures

Figure 6. Reptiles from the Muschelkalk Group. A, B. Placodontid placodont Placodus gigas, holotype (SNSB-BSPG AS VII 1208), cranium in ventral view (A) and mandible in occlusal view (B). Scale bar: 2 cm. Photographs courtesy of O. W. M. Rauhut (SNSB-BSPG). C. Cyamodontid placodont Cyamodus kuhnschnyderi, holotype (SMNS 15855), cranium in ventral view. Scale bar: 2 cm.