Mastodonsaurus giganteus Jaeger, 1828

Schoch, Rainer R., Witzmann, Florian, Moreno, Raphael, Werneburg, Ralf & Mujal, Eudald, 2024, Growing giants: ontogeny and life history of the temnospondyl Mastodonsaurus giganteus (Stereospondyli) from the Middle Triassic of Germany, Fossil Record 27 (3), pp. 401-422 : 401-422

publication ID	https://doi.org/10.3897/fr.27.125379
publication LSID	lsid:zoobank.org:pub:FF6C32D8-1CB8-4779-A070-7CEB3B837EAD
persistent identifier	https://treatment.plazi.org/id/A8503456-1FA3-5D9F-A68F-5191D2B62BE9
treatment provided by	by Pensoft
scientific name	Mastodonsaurus giganteus Jaeger, 1828
status

Treatment

1828 Mastodonsaurus Jaeger : p. 35, nomen imperfectum.

* 1828 Salamandroides giganteus Jaeger : p. 38.

1841 Labyrinthodon jaegeri Owen : p. 227

1844 Mastodonsaurus jaegeri Meyer : p. 11. pls. 6–7.

1844 Mastodonsaurus jaegeri Plieninger : p. 57, pls. 3–7.

1850 Mastodonsaurus giganteus Quenstedt : p. 2.

1889 Mastodonsaurus giganteus Fraas : p. 32, figs 1–5.

1922 Mastodonsaurus giganteus Huene : p. 400, figs 1–12.

1999 Mastodonsaurus giganteus Schoch : p. 42, figs 8–49.

2007 Mastodonsaurus giganteus Moser and Schoch : p. 1245, figs 2, 3, 5–9.

Holotype.

GPIT Am 678, an occiput with exoccipital condyles and posterior portion of parasphenoid, estimated skull length about 61 cm ( Moser and Schoch 2007, fig. 9).

Type locality and age.

Alum mine with main entrance at Parkschule north of the Kocher River, Gaildorf (Baden-Württemberg, Germany) ( Meyer and Plieninger 1844). The fossiliferous sequence was locally restricted and remained poorly constrained for a long time within the Lower Keuper (Fig. 2 View Figure 2 ; Weber 1992; Hagdorn et al. 2015). It encompassed coal, coaly mudstones and siltstones (Plieninger in Meyer and Plieninger 1844; Kurr 1852; Quenstedt 1880). Recent sections measured at briefly exposed outcrops in the vicinity of the type locality confirmed that the sequence was stratigraphically immediately below the Hauptsandstein or main sandstone unit of the Lower Keuper, corresponding to the Estherienschichten (Hans Hagdorn and Theo Simon, pers. comm. 2022), as had been suggested by Weber (1992). The age of the Lower Keuper is considered Longobardian (late Ladinian, late Middle Triassic).

Referred material.

Fig. 2 View Figure 2 provides an overview of the samples of M. giganteus studied in the present paper.

Gaildorf G 2 (locus typicus, top of Estherienschichten, below Hauptsandstein). GPIT 1824, occiput (61 cm skull length). SMNS 4698, complete skull with mandibles (62 cm SL). SMNS 4707, complete skull with mandibles (68 cm SL) and anterior part of vertebral column (9 intercentra). SMNS 4938, tip of snout (estimated 65 cm SL). SMNS 54679, complete skull with mandibles (60 cm SL; this specimen was erroneously reported by Moser and Schoch (2007) as measuring 74 cm). A large snout (about 107 cm SL, described in Meyer and Plieninger 1844 and figured by Meyer 1855), reported as heavily damaged by Fraas (1889), has long been lost ( Schoch 1999); here we provide an interpretation of Meyer’s (1855) figure in Fig. 5 D View Figure 5 .

Michelbach an der Bilz M 1 (Sandige Pflanzenschiefer, layer M 1). MHI 1070, series of intercentra of juvenile specimen.

Kupferzell K 3 (Untere Graue Mergel, green layer K 3 of Schoch et al. 2022). SMNS 54675, complete skull (60.5 cm), almost undistorted, with perfect braincase. SMNS 54678, complete skull (54.5 cm). SMNS 80704, complete skull (55 cm) with mandible. SMNS 80889, complete skull (59 cm) with mandible. SMNS 80890, postorbital part of skull (45.5 cm). SMNS 80905, disarticulated skull (about 45 cm). SMNS 80945, disarticulated skull (60 cm). SMNS 81075, disarticulated skull (48 cm). SMNS 81310, giant specimen, including complete mandible (110 cm; 88.5 cm SL) with few remnants of the palate and a total of 28 presacral and 6 caudal vertebrae. SMNS 81368, posterior part of palate. SMNS 84030, posterior margin of skull (estimated 65 cm SL). Symphyses of tiny specimens ( SMNS 97035, approx. 12–15 mm mm SL; SMNS 97036, 25 mm SL). Isolated material: supratemporal: SMNS 80886, 81153–81156; postorbital: SMNS 81161–81162; squamosal: 80946, 80947, 81164; pterygoid: SMNS 81316, 81318, 81324–81325; parasphenoid: SMNS 81326, 81328, 81330–81332; exoccipital: 80980–80988, 81002–81005, 81013, 81018–81024; interclavicle: SMNS 81282–91; clavicle: SMNS 81298; cleithrum: SMNS 81208–81209, 81257, 81264; intercentra: SMNS 84172 (13), 84173, 84194 (4), 84195, 84206, 84208, 84212 (10), 84213 (11), 84291 (5).

Kupferzell K 4 (Untere Graue Mergel, yellow-brown layer K 4 of Schoch et al. 2022). SMNS 54676, complete skull (56 cm). SMNS 54677, complete skull (51 cm) with mandible. SMNS 80249, posterior rim of skull (65 cm). SMNS 80878. Near-complete skull (about 65 cm) with parts of mandible. SMNS 80887, snout fragment (54 cm SL). SMNS 80913, fragmentary skull (65 cm total length) with 28 presacral vertebrae. SMNS 83293, fragmentary skull (60 cm). SMNS 83312, fragmentary skull (45 cm). SMNS 97038–97042, skull fragments (68, 50, 47, 50, 57 cm SL, respectively). Isolated material: supratemporal: SMNS 80865, postparietal: 81000, 83260; tabular: SMNS 81091–81098; exoccipitals: SMNS 80917, 80926, 80956, 80957, 80979, 80980, 80982, 80989, 80990, 80994, 80996, 80998, pterygoid: SMNS 81320, 81321; interclavicle: SMNS 81270–81276; cleithrum SMNS 81210, 81261, 81262; intercentra: SMNS 84138, 84139 (14), 84145 (7), 84200, 84207 (6), 84210, 84211.

Markgröningen ( Fraas 1889, p. 5: “ 10 m above Hauptsandstein ” = Untere Graue Mergel). SMNS 4974. Skull without cheek regions (71.3 cm SL).

Vellberg E 5 (Untere Graue Mergel, brown layer E 5 of Schoch and Seegis 2016). MHI 1991 / 22, complete skull (50.5 cm). MHI 1992 / 20, complete skull (59.5 cm). MHI 1992 / 41, complete skull (42 cm). MHI Ku / UC 53 le 1 (53 cm). MHI Ku / UC 53 le 2 (34.6 cm). SMNS 81966, complete skull (51 cm) with mandible.

Vellberg E 6 (Untere Graue Mergel, grey layer E 6 of Schoch and Seegis 2016). MHI 1992 / 1, complete large skull (72 cm) with mandible detached. MHI 1992 / 31, complete juvenile skull (30 cm). MHI 1992 / 42, complete juvenile skull (28.6 cm). MHI - Ku 1993 / 4, tiny interclavicle. MHI - Ku 1993 / 5, juvenile interclavicle. SMNS 97043, complete skull (39 cm). MHI Ku / UC 54 le 1, mandible (24.1 cm). MHI Ku / UC 54 le 2, mandible (20 cm). MHI Ku / UC 54 le 3, mandible (35 cm). MHI Ku / UC 1, mandible (SL approx.: 37 cm). MHI Ku / UC 2, mandible (100.8 cm SL). SMNS 92128, complete, highly fractured skull (60 cm length). SMNS 97037, posterior portion of juvenile skull (15 cm SL).

Vellberg E 7 (Anoplophora Dolomite, pale yellow dolostone unit E 7 of Schoch and Seegis 2016). MHI 1794 / 3, complete, slightly deformed skull (62 cm). MHI 1991 / 1, complete skull in 3 D with mandible (54.2 cm). MHI 1991 / 4, two partial skulls (32 and 34 cm). MHI 1991 / 5, snout (estimated 66.6 cm SL). MHI 1991 / 6, partial skull (53.9 cm). MHI 1991 / 7, snout (estimated 35 cm SL). MHI 1991 / 8, mandible (estimated 58.3 cm SL). MHI 1991 / 11, complete skull with deformed snout (38 cm). MHI Ku / UC 54 le, mandible (52.7 cm). MHI Ku / UC 54 le 1, skull (54.4 cm). MHI Ku / UC, skull (54 cm).

Arnstadt (Oberes Dunkles Band, layer 42, dark coaly siltstone of Werneburg in Hagdorn et al. 2015). NHMS - WT 3323-3368, partial skull and mandible (estimated 101 cm SL; Werneburg and Witter 2005).

Hoheneck H 1 (Lingula-Dolomit, Hoheneck facies). SMNS 740, palate (52 cm; Fraas 1889). SMNS 4194 (66 cm; skull roof in internal view; Fraas 1889).

Diagnosis.

Autapomorphies (in contrast to M. cappelensis , see Schoch et al. 2023): (1) Orbits with pointed anterior end and narrow interorbital distance (Figs 3 View Figure 3 , 4 View Figure 4 ; IOW: SL = 0.095); (2) medial premaxillary teeth enlarged (Fig. 5 C, D View Figure 5 ); (3) tusks in palate and especially in the symphysis greatly enlarged (Figs 5 View Figure 5 , 6 View Figure 6 ), (4) postorbital larger than supratemporal; (5) squamosal wide to give broadened cheek; (6) interclavicle with elongate anterior process; (7) intercentra of the trunk dorsally closed in juveniles and adults (Fig. 6 N – Q View Figure 6 ).

Comment.

The three complete skulls from Gaildorf G 2 and most specimens from Vellberg E 5–7 are all heavily affected by crushing and distortion, whereas the Kupferzell specimens are preserved almost in 3 d thanks to early cementation of sediment. Morphological differences especially in the squamosal embayment and cheek may therefore be caused by post-mortem processes rather than reflect morphological variation. We did not spot consistent differences between the Gaildorf G 2 sample and other samples described here, therefore consider all samples as belonging to the type species.

The Kupferzell and Vellberg samples are morphologically very similar and stratigraphically well constrained (both fall within above the lagoonal deposit K 1 = E 4 and below the base of the Anoplophora Dolomite at the top of the Untere Grauel Mergel).