Late triassic turtles from South america

Area of Science:

• Paleontology
• Vertebrate Paleontology
• Mesozoic Reptiles

Background:

• The fossil record of early turtles is sparse, particularly from the Southern Hemisphere.
• The evolutionary history and diversification of turtles (Testudines) remain areas of active research.
• Previous turtle discoveries in South America did not extend into the Triassic period.

Purpose of the Study:

• To describe new basal turtle fossils from the Triassic of Argentina.
• To reassess the evolutionary relationships and diversification of early turtles.
• To extend the known temporal and geographic range of turtles in South America.

Main Methods:

• Excavation and preparation of two fossil turtle skeletons from the Norian (Late Triassic) strata of northwestern Argentina.
• Comparative anatomical analysis of the fossil material, focusing on key skeletal features of turtles.
• Phylogenetic analysis to determine the evolutionary relationships of the new taxon within Testudines.

Main Results:

• Discovery of two new fossil turtle skeletons, including a nearly complete specimen, representing a new genus and species: Palaeochersis talampayensis.
• Palaeochersis talampayensis is placed within the family Australochelidae, previously known only from the Early Jurassic of South Africa.
• The new discovery extends the South American turtle fossil record into the Late Triassic, approximately 60 million years earlier than previously known.

Conclusions:

• Australochelidae represents a basal lineage of turtles, with Palaeochersis talampayensis providing crucial insights into their morphology and distribution.
• Turtle diversity was present by the Late Triassic, challenging previous notions of their evolutionary timeline.
• The findings suggest that the major turtle clades, including Casichelydia, likely originated during the Jurassic period.