Angolachelonia is a clade of

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

turtles Turtles are reptiles of the order Testudines, characterized by a special shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) and Cryptodira (hidden necked turtle ...

from the

Late Jurassic The Late Jurassic is the third Epoch (geology), epoch of the Jurassic Period, and it spans the geologic time scale, geologic time from 161.5 ± 1.0 to 143.1 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic stratum, strata.Owen ...

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

Eurasia Eurasia ( , ) is a continental area on Earth, comprising all of Europe and Asia. According to some geographers, Physical geography, physiographically, Eurasia is a single supercontinent. The concept of Europe and Asia as distinct continents d ...

. The group is defined as all taxa derived from the ancestor of the type genus ''

Angolachelys ''Angolachelys'' is an extinct genus of African marine turtle which existed in Angola during the Turonian stage of the Late Cretaceous. The type species is ''Angolachelys mbaxi''. The type MGUAN-PA includes skull, jaw, and postcranial fragments f ...

'' and '' Solnhofia'', a definition that could potentially encompass a clade of entirely marine turtles. Angolachelonia was originally inclusive of only ''Solnhofia'', ''Angolachelys'' and '' Sandownia'' when originally conceived by Octavio Mateus and colleagues in

2009 2009 was designated as the International Year of Astronomy by the United Nations to coincide with the 400th anniversary of Galileo Galilei's first known astronomical studies with a telescope and the publication of Astronomia Nova by Joha ...

, but later phylogenetic analyses by Serjocha Evers and Roger Benson in

2018 Events January * January 1 – Bulgaria takes over the Presidency of the Council of the European Union, after the Estonian presidency. * January 4 – SPLM-IO rebels loyal to Chan Garang Lual start a raid against Juba, capital of ...

unites the family Sandownidae, including ''Angolachelys'' and ''Sandownia'' among other taxa, with the entirely Late Jurassic clade

Thalassochelydia Thalassochelydia is a clade of extinct marine turtles from the Late Jurassic and earliest Cretaceous of Europe and South America. The group is defined as including '' Eurysternum'', ''Plesiochelys'' and '' Thalassemys'' to the exclusion of '' Pel ...

, 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. A 2021 study found more evidence for Sandownidae and Thalassochelydia being close to one another, and found that

Protostegidae Protostegidae is a family of extinct sea turtle, marine turtles that lived during the Cretaceous period. The family includes some of the largest sea turtles that ever existed. The largest ''Archelon'' had a head long. Like most sea turtles, the ...

may also be closely linked to the group.

References

{{Taxonbar, from=Q9154611 Cretaceous turtles Paleogene turtles Testudinata