Tasbacka

Tasbacka is an extinct genus of sea turtle containing several species.^[1][3]

Tasbacka Temporal range: Campanian-Eocene, Campanian–48.6[1][2] PreꞒ Ꞓ O S D C P T J K Pg N
T. danica fossil from the Fur Formation
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Testudines
Suborder:	Cryptodira
Superfamily:	Chelonioidea
Family:	Cheloniidae
Tribe:	Cheloniini
Genus:	Tasbacka Nessov, 1987
Type species
Tasbacka aldabergeni Nessov, 1987
Other species
Tasbacka danica Karl & Madsen, 2012 Tasbacka germanica Karl, Gröning & Brauckmann, 2019 Tasbacka ouledabdounensis Tong & Hirayama, 2002 Tasbacka ruhoffi Weems, 1988 Tasbacka salisburgensis Karl, 1996

Though the type species, T. aldabergeni, has only been found in Kazakhstan,^[4] Tasbacka had a wide distribution. T. ruhoffi was found in the eastern USA,^[5] T. danica in modern Denmark, T. ouledabdounensis in modern Morocco, T. salisburgensis in modern Austria,^[3] and T. germanica in modern Germany.^[2]

In 2008, researchers found a well-preserved, juvenile specimen of T. danica in Denmark's Fur Formation.^[6] Some of the fossil's soft tissues remained.^[7] The specimen, dating back to 54 Ma, contained eumelanin. This pigment would've given the hatchling a dark shell while it was alive. Modern sea turtle hatchlings also have dark shells; while a hatchling floats on the ocean's surface, its dark coloring enables it to absorb heat from the sun and avoid predatory birds. The existence of similar pigment on an ancient specimen suggests sea turtles evolved this survival trait millions of years ago.^[6]