Brachyopoidea

Nonsrirach, Thanit, Manitkoon, Sita & Lauprasert, Komsorn, 2021, First occurrence of brachyopid temnospondyls in Southeast Asia and review of the Mesozoic amphibians from Thailand, Fossil Record 24 (1), pp. 33-47 : 36-38

Brachyopoidea indet.

Reference material

TF 3328 ( Fig. 3a–d ), TF 3329 ( Fig. 3e–h ), and TF 3144 ( Fig. 3i–l ), intercentra ( Buffetaut et al., 1994a, c).

Formation/age

Klong Min Formation (Middle or Upper Jurassic) and Phu Kradung Formation (Upper Jurassic).

Locality and sediment

TF 3328 and TF 3329 were found in a road cut outcrop near Mab Ching village, Thung Song District, Nakhon Si Thammarat Province, in the southern peninsula of Thailand, which belongs to the Sibumasu block. This outcrop is formed by greyish clays and siltstones, with some freshwater limestone intercalations. It belongs to non-marine Middle or Upper Jurassic rocks based on charophyte algae, palynomorphs, and diatoms ( Lei, 1993; Buffetaut et al., 1994c; Girard et al., 2020).

TF 3144 was found in a road cut outcrop at kilometer 68, along Highway 12 from Chum Phae to Lom Sak, in Khon Kaen Province. This area consists of reddish-grey silts and fine-grained reddish sandstone deposited in a meandering river channel ( Buffetaut et al., 1994a), which belongs to the Indochina block.

Description

All specimens are wedge-shaped intercentra. Both anterior and posterior surfaces are concave and show a marked circular notochordal canal, which is visible as a circular pit. The pleurocentra are reduced or absent, which is a typical feature of stereospondyls ( Milner et al., 1994; Witzmann and Gassner 2008). The wedge-shaped morphology and the notochordal pit of TF 3328, TF 3329, and TF 3144 is consistent with the intercentrum morphology of the Brachyopoidea ( Shishkin, 1991; Warren et al., 1997, 2011; Warren and Dammiani, 1999), which are similar to the intercentra discovered from the Jurassic Indochina block, e.g., Gobiops desertus from the Gobi Desert of Mongolia ( Shishkin, 1991).

Figures

Figure 3. Thai Brachyopoidea indet. intercentra, TF 3228 (a–d), TF 31229 (e–h), TF 3144 (i–l, after Buffetaut et al., 1994b; fig. 1), and KS37-8 (m–p). Thai Brachyopidae indet. intercentra, KS34-1474 (q–t) and KS34-1489 (u–x). Anterior views (a, e, i, m, q, u), posterior views (b, f, j, n, r, v), left views (c, g, k, o, s, w), and right views (d, h, l, p, t, x).