Chelonian eggshells from the Lower Cretaceous Kuwajima Formation of the Tetori Group, Central Japan

Shinji Isaji, Ai Matsushita, Ren Hirayama

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Chelonian eggshell fossils from the Lower Cretaceous Kuwajima Formation of the Tetori Group are described. The eggs were originally spherical or ellipsoidal in shape. The eggshells consist of a single layer of spherulitic shell units composed of needle-like crystallites originating from a nucleation center. This corresponds to modern rigid-shelled chelonian eggs. The eggshell fragments are commonly found buried together and are known from deposits of subaerial environments, such as vegetated swamps. In contrast, the vast majority of turtle remains are known primarily from nearby shallow lake deposits, indicating that they are aquatic; no terrestrial turtles are known from this formation. These taphonomic settings suggest that the eggs were laid on land by lacustrine turtles in a process still apparent today.

Original languageEnglish
Pages (from-to)29-36
Number of pages8
JournalPaleontological Research
Issue number1
Publication statusPublished - 2006 Apr 30



  • Chelonian eggshell
  • Early Cretaceous
  • Kuwajima Formation
  • Tetori Group

ASJC Scopus subject areas

  • Palaeontology
  • Ecology, Evolution, Behavior and Systematics

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