Albula sp.

Ostrowski, Summer A., 2021, Late Cretaceous Elopomorpha (Actinopterygii: Teleostei) from the Mahajanga Basin of Madagascar and impacts on paleobiogeography, Palaeontologia Electronica (a 31) 24 (3), pp. 1-15 : 3-4

Albula sp.

Figure 2

Material. Tooth plate ( UA 11388) and dentary ( DMNH EPV. 136301).

Occurrence. Berivotra Study Area (Anembalemba Member).

Description. The oral tooth plate UA 11388 ( Figure 2 A-B) measures 6 mm along the longest axis and 4 mm wide. The base is made of thin bone with broken edges. On the occlusal side, there are 37 pedestaled teeth ranging in size from 0.5-1.0 mm in diameter across the crown and 1 mm in height. There are 10 alveolar pits, most filled with broken tooth bases. The opposite side of the bony base has a smooth texture with a small ridge of bone, likely a muscle scar, less than 2 mm in height. This incomplete specimen does not have enough anatomical information to determine the exact placement of the bone within the oral cavity.

DMNH EPV. 136301 ( Figure 2 C-D) is a left dentary with a complete symphysial end, but incomplete, posterior articular end. The dentary measures 2.1 cm long, 0.5 cm wide, and 1.0 cm at its deepest point. Covering the dorsal surface, there is a rectangular tooth patch with 134 distinct, evenly spaced pits to accommodate villiform teeth. Each tooth pit measures 1 mm in diameter. The symphysial end is 0.7 cm deep and vertically oriented. The lateral side of the dentary has several large foramina. The ventral margin has a prominent keel with a deep groove and a series of foramina for a sensory canal.

Remarks. Albulids have tooth plates with a crushing dentition that are used in benthic environments for preying upon small invertebrates ( Forey, 1973). Within Albula , there are hundreds of small, pedestal-shaped teeth within the oral cavity as depicted by Applegate (1970). The dentary of DMNH EPV. 136301 ( Figure 2 C-D) is directly comparable with similarly aged fossils of Albula dunklei (FMNH P27494) from the Selma Formation in Alabama ( Applegate, 1970) and recent Albula vulpes (UMMZ 186965-S) skeletons. Albula maxillae and dentaries have a large “tooth patch” to accommodate hundreds of villiform teeth ( Applegate, 1970). The modern Albula dentary was described as having a near vertical symphysial margin, an extremely wide gutter on the ventral portion of the dentary (for the mandibular sensory canal) that opens laterally for most of its length ( Nybelin, 1976) as seen in DMNH EPV. 136301.

Figures

FIGURE 2. Albula sp. fossils from the Maevarano Formation. A-B, occlusal and lateral view of tooth plate (UA 11388). C-D, occlusal and ventral view of dentary (DMNH EPV. 136301). Scale bars equal 1 cm.