Apollochelys

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 Kingdom:
 * *A. cerrejonensis*
* *A. calyptosoma*
* *A. urus*

***Apollochelys*** is an extinct genus of soft-shell turtle well-known from the Cerrejón Formation in Colombia (*A. cerrejonensis)*. It lived approximately 60 mya, and was the only soft-shell turtle from South America. It has also been found in North America (*A. calyptosoma* and *A. urus*) and Asia (*A. urus*).

The type species, ***A. cerrejonensis***, was discovered in 1947 in the Cerrejon Formation of Colombia. However, it wasn't named until 1962, when paleontologist Dean Hamilton described it. The first specimen of *Apollochelys* consisted of a left pes, 2 ribs, a partial sternum, a complete mandible, 2 metatarsals, and a damaged vertebra. Initially, many scientists considered *Apollochelys* to be a *nomen dubium*, because it had no features that set it apart from the related *Jupiterchelys*. Fossils of *A. cerrejonensis* found in the 1980's provided evidence that it was a distinct genus, including a complete, very elongated skull, several bulky tibias, and more than 11 vertebrae. The first complete fossil of *A. cerrejonensis* was found in 1993. This fossil revealed that *Apollochelys* was an unusual soft-shelled turtle, the only one from South America. The next year, the subfamily apollochelyinae was erected by Clifford Brant. At this time, it included *Apollochelys*, *Jupiterchelys*, *Testudodectus*, and *Montezumasaurus*. The subfamily would later expand to include other genera of soft-shell turtles, most notably *Necrovalvus*.

## History

*Apollochelys* was first found in the Cerrejon formation in northern Colombia. Although the first specimen was recovered from the fossil site in 1947, it wasn't named until 1962. It was eventually given the name *Apollochelys cerrejonensis* by Dean Hamilton. In 1965, several scientists at the National University of Colombia-Bogota Campus suggested that *A. cerrejonensis* was a *nomen dubium*, based on fossils of the extremely similar *Jupiterchelys*. In the following years, many scientists followed suit, with many considering *Apollochelys* to be a junior synonym of *Jupiterchelys*. However, a few more fossils of *A. cerrejonensis* were discovered in 1981, including 2 vertebrae and a heavily-built tibia. Some scientists considered the robustness of the tibia alone to be enough to separate *Apollochelys* from *Jupiterchelys*. In 1988, more fossils of *Apollochelys* were recovered from the Cerrejon Formation. Among these were 10 vertebrae, 4 tibias, and a complete skull. "The skull", noted paleontologist Arnold Marx, "was unusually elongate and heavily built, perhaps pointing towards carnivory."

In 1993, a complete specimen of *A. cerrejonensis* was excavated from the Cerrejon Formation. This fossil was more than enough to convince scientists that *Apollochelys* was an animal distinct from *Jupiterchelys*. Among the most unusual traits of the fossil was the fact that the shell of *Apollochelys* was flattened like that of a soft-shell turtle. In February 1994, the subfamily apollochelyinae was erected to include *Apollochelys*, the redescribed *Jupiterchelys*, and a couple other soft-shell turtles initially thought to belong to trionychinae, namely *Testudodectus* and *Montezumasaurus*.

Another fossil of *Apollochelys* was recovered from the North American Red Gulch Formation in 2010. It was different enough from *A. cerrejonensis* to be put in a different species, specifically *A. calyptosoma*. The same year, more fossils were found at the Red Gulch Formation, and while some of them were obviously *A. calyptosoma*, some of them were an entirely new species, which was named *A. urus* in 2013. By 2018, more than 20 complete and partial specimens of *A. cerrejonensis* had been discovered in the Cerrejon Formation, making it a well-studied species. Additional specimens of *A. urus* were found in the Chinese Hongwang Formation in early 2019.