''Antarctilamna'' is an extinct genus of

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...

shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimo ...

originally exemplified by ''Antarctilamna prisca'' from South Eastern Australia and Antarctica. The latest occurring described species is ''Antarctilamna ultima'' from the

Waterloo Farm lagerstätte The Waterloo Farm lagerstätte is a Famennian lagerstätte in South Africa that constitutes the only known record of a near-polar Devonian coastal ecosystem. History and discovery The Waterloo Farm Lagerstätte is an approximately 360 millio ...

in South Africa. ''Antarctilamna'' has robust ctenacanthid-like spines which lack a deep insertion area, and are borne in front of the first dorsal fin; in addition to distinctive diplodont teeth with small intermediate cusps. ''Antarctilamna''-like spines, known from the Bunga Beds locality in Australia have been ascribed to ''A. prisca''.

Distribution

Fossils of ''Antarctilamna'' have been found in Antarctica and Australia. Similar dissociated spines from the Devonian are often referred to as ''Antarctilamna'' sp.(for example from Bolivia ( Catavi Formation), Colombia (

Cuche Formation The Cuche Formation ( es, Formación Cuche, Cc) is a geological formation of the Floresta Massif, Altiplano Cundiboyacense in the Eastern Ranges of the Colombian Andes. The sequence of siltstones, shales, and sandstone beds dates to the Late Devo ...

, Boyacá), and

Pont de Suert Pont, meaning "bridge" in French, may refer to: Places France * Pont, Côte-d'Or, in the Côte-d'Or ''département'' * Pont-Bellanger, in the Calvados ''département'' * Pont-d'Ouilly, in the Calvados ''département'' * Pont-Farcy, in the Calva ...

, Spain. Many of these tentative diagnoses may not be congeneric, as other early sharks bore similar spines – early Devonian Doliodus for example bore similar looking spines on both the dorsal and paired fins.''Antarctilamna''
at

Fossilworks Fossilworks is a portal which provides query, download, and analysis tools to facilitate access to the Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals ...

.org

Species

''Antarctilamna prisca'' (sp. nov.)

The description of ''Antarctilamna prisca'' includes material derived from both Antarctic and New South Wales localities, the prior comprising the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

, a partial decayed carcass with dermal denticles, a fin spine and teeth preserved. Material from New South Wales comprises isolated spines. On this basis the authors proposed a tentative correlation between the lower part of the Aztec Siltstone of South Victoria and the Bunga Beds of the New South Wales south coast.

''Antarctilamna ultima'' (sp. nov.)

''Antarctilamna ultima'' is one of two shark species diagnosed from the

in South Africa. It is described from an assemblage of elements including a dorsal fin spine, jaws and diplodont teeth derived from an individual that was approximately 1m long. A number of isolated spines, larger isolated teeth, and a partial skull are also presumed to be long to this species. A rough estimate assuming a constant relationship between tooth width, mandibular length and body length suggests that ''Antarctilamna ultima'' reached several metres in length. ''Antarctilamna ultima'' are known from dorsal fin spines, teeth, cartilaginous elements, skin impressions and a small whole-bodied impression ''Antarctilamna ultima'' is the first recorded Devonian chondrichthyan known from a juvenile specimen, and the latter's juvenile status is supported not just by its extremely small size, but also by its very large head and branchial region, which together exceeded a quarter of its body length. Studies suggests that large sharks frequently entered the Waterloo Farm estuary from the sea when the mouth was open, in order to forage, but it is also possible that they gave birth within the estuarine lake which acted as a nursery area for these species.Gess, Robert W.; Whitfield, Alan K. (August 22, 2020). "Estuarine fish and tetrapod evolution: insights from a Late Devonian (Famennian) Gondwanan estuarine lake and a southern African Holocene equivalent". Biological Reviews. 95 (4): 865–888. doi:10.1111/brv.12590 – via Wiley Online Library. Antarctilamna ultima, first dorsal fin spine from the Waterloo Farm lagerstatte

Antarctilamna ultima, first dorsal fin spine from the Waterloo Farm lagerstatte

References

Bibliography