Angolachelonia

Angolachelonia Temporal range: Late Jurassic to Paleogene, Oxfordian–Paleocene PreꞒ Ꞓ O S D C P T J K Pg N
Angolachelys mbaxi
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Pantestudines
Clade:	Testudinata
Clade:	Mesochelydia
Clade:	Perichelydia
Clade:	†Angolachelonia Mateus et al., 2009
Subgroups[1]
Sandownidae Thalassochelydia

Angolachelonia is a clade of extinct turtles from the Late Jurassic to Paleogene of Eurasia. The group is defined as all taxa derived from the ancestor of the type genus Angolachelys and Solnhofia, a definition that could potentially encompass a clade of entirely marine turtles.^[1] Angolachelonia was originally inclusive of only Solnhofia, Angolachelys and Sandownia when originally conceived by Octavio Mateus and colleagues in 2009,^[2] but later phylogenetic analyses by Serjocha Evers and Roger Benson in 2018 unites the family Sandownidae, including Angolachelys and Sandownia among other taxa, with the entirely Late Jurassic clade Thalassochelydia, where Solnhofia may be a basal member. While the placement of Solnhofia is weak and the clade that Angolachelonia represents may change with further analysis, the clade of Sandownidae and Thalassochelydia is well-supported, and does not collapse despite the uncertain evolutionary history of the group. Three alternative potential origins of Angolachelonia sensu Evers and Benson are shown below.^[1]

Testudinata basal stem-group turtles Xinjiangchelyidae Sinemydidae/Macrobaenidae Angolachelonia Testudines Pleurodira non-chelonioid cryptodires Chelonioidea

Testudinata basal stem-group turtles Xinjiangchelyidae Sinemydidae Testudines Pleurodira non-chelonioid cryptodires Macrobaenidae Angolachelonia Chelonioidea

Testudinata basal stem-group turtles Xinjiangchelyidae Sinemydidae/Macrobaenidae Testudines Pleurodira non-chelonioid cryptodires Angolachelonia Chelonioidea

A 2021 study found more evidence for Sandownidae and Thalassochelydia being close to one another, and found that Protostegidae may also be closely linked to the group.^[3]

References

1. Evers, S.W.; Benson, R.B.J. (2018). "A new phylogenetic hypothesis of turtles with implications for the timing and number of evolutionary transitions to marine lifestyles in the group". Palaeontology. 62 (2): 93–134. doi:10.1111/pala.12384.
2. Octávio Mateus; Louis Jacobs; Michael Polcyn; Anne S. Schulp; Diana Vineyard; André Buta Neto; Miguel Telles Antunes (2009). "The oldest African eucryptodiran turtle from the Cretaceous of Angola" (PDF). Acta Palaeontologica Polonica. 54 (4): 581–588. doi:10.4202/app.2008.0063. S2CID 55919209.
3. Joyce, Walter G.; Anquetin, Jérémy; Cadena, Edwin-Alberto; Claude, Julien; Danilov, Igor G.; Evers, Serjoscha W.; Ferreira, Gabriel S.; Gentry, Andrew D.; Georgalis, Georgios L.; Lyson, Tyler R.; Pérez-García, Adán (2021-02-09). "A nomenclature for fossil and living turtles using phylogenetically defined clade names". Swiss Journal of Palaeontology. 140 (1): 5. doi:10.1186/s13358-020-00211-x. hdl:11336/155192. ISSN 1664-2384.