Chondrichthyans, or Cartilaginous Fish, are among the most numerous Vertebrate fossils in the geological record, but almost all these fossils are of isolated teeth. Whole-body fossils of Chondrichthyans, in contrast are extremely rare, limiting our understanding of the morphology and biology of ancient members of this group.
The oldest known body fossils of Batomorphs, or Rays, date back to the Jurassic Period, considered to be an important interval in Shark and Ray evolution, and come from a series of 'Konservat-Lagerstätten', the most notable of which is the Solnhofen Limestone, of southern Germany, which records a series of deposits laid down in the Kimmeridgian-Tithonian (i.e. between 154.8 and 143.1 million years ago) in a series of islands, known as the Solnhofen Archipelago, on the edge of the Tethys Sea with many enclosed, placid, lagoons that had limited access to the open sea and where salinity rose high enough that the resulting brine could not support life. The Solnhofen Limestone records a range of Vertebrate fossils in exquisite detail, including Holocephalians (Chimeras), Hybodont Sharks, Selachimorph Sharks, and at least two genera of Batomorphs.
Until fairly recently, all Batomorphs from the Solnhofen Limestone were refered to the genera Asterodermus and Spathobatis, but recent studies have suggested that none of the Solnhoffen specimens can be assigned to Spathobatis, a genus originally described from French specimens, with the German specimens assigned to Spathobatis reassigned to a new genus, Aellopobatis. All known specimens of Asterodermus and Aellopobatis from the Solnhoffen Limestone are thought to be of Tithonian age, although many specimens were collected decades ago from working quarries, and may not be dated accurately.
In a paper published in the journal PLoS One on 23 January 2025, Julia Türtscher and Patrick Jambura of the Department of Palaeontology and the Vienna Doctoral School of Ecology and Evolution at the University of Vienna, Frederik Spindler of PALAEONAVIX, and Jürgen Kriwet, also of the Department of Palaeontology and the Vienna Doctoral School of Ecology and Evolution at the University of Vienna, deescribe a new species of Batomorph from the Kimmeridgian Painten site within the Franconian Alb of central Bavaria.
The new species is described from a single specimen, DMA-JP-2010/007, and is named Apolithabatis seioma, where 'Apolithabatis' means 'Fossil Ray' in Greek, while 'seioma' derives from the Greek 'seismós', meaning 'shake', in reference to the way in which the fossil was extracted from the rock. The single known specimen of Apolithabatis seioma is at least 120 cm in length, with a heart-shaped disc and a long narrow tail. It has two dorsal fins, both behind the pectoral girdle (i.e. on the tail).
Previous phylogenetic studies have recovered Jurassic Batomorphs as a part of the crown group (i.e. descended from the last common ancestor of all living members of the group), with the Torpediniformes (Electric Rays) forming the sister group to all other members of the group. However, Türtscher et al. recovered Apolithabatis seiomai, along with the other Jurassic genera Aellopobatis, Asterodermus, Belemnobatis, Kimmerobatis, and Spathobatis, in a distinct clade which has a sister group relationship to all extant Batomoph groups (including the Torpediniformes). Since this implies that this group is not descended from the last common ancestor of all living Batomorphs, Türtscher et al. regard this group, which they name the Order Apolithabatiformes, to stem group Batomorphs.
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