Angolachelonia is a clade of extinct

turtles Turtles are an order of reptiles known as 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 tur ...

from the

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name ...

to Paleogene of

Eurasia Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago ...

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

Angolachelys ''Angolachelys'' is an extinct genus of African eucryptodiran 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 frag ...

'' 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 Octavio is a Spanish language masculine given name. In the Portuguese language the given name Octavio or Octávio is also found, but in Portuguese the normal spelling is Otávio. It is also used as a surname in the Philippines. Individuals * Octa ...

and colleagues in 2009, but later phylogenetic analyses by Serjocha Evers and Roger Benson in

2018 File:2018 Events Collage.png, From top left, clockwise: The 2018 Winter Olympics opening ceremony in PyeongChang, South Korea; Protests erupt following the Assassination of Jamal Khashoggi; March for Our Lives protests take place across the Unit ...

unites the family

Sandownidae Sandownidae is a family of extinct marine turtles from the Cretaceous and Paleogene distributed around the Atlantic Ocean and adjacent areas. The family is defined as all taxa closer to the type genus '' Sandownia'' than to '' Pelomedusa'', '' ...

, 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 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, they had fl ...

may also be closely linked to the group.

References

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