EVIDENCE OF HIGHLY CONSERVED REPRODUCTIVE MODE IN HOLOCEPHALAN CHONDRICHTHYANS: A CHIMAEROID EGG CAPSULE FROM THE LATE TRIASSIC OF NEW ZEALAND

A Late Triassic chimaeroid egg capsule from New Zealand is described as a new ichnospecies in the ichnogenus Chimaerotheca. The fossil egg capsule is preserved as a positive impression on a block of very fine-grained sandstone recovered from the Murihiku Terrane of the South Island of New Zealand, which is dated as Warepan or Otapirian in the local New Zealand stage system, equivalent to late Norian or Rhaetian internationally. The egg capsule impression is spindle-shaped and consists of a narrow flask-like central embryo chamber surrounded by a ribbed membrane. In overall aspect the fossil is strikingly similar to egg capsules of the extant chimaeroid Callorhinchus milii, which occurs today in New Zealand waters and off of southern Australia. The specimen represents the oldest formally reported record of a chondrichthyan from New Zealand, and extends the southern Gondwanan high paleolatitude fossil record of chimaeroids by approximately 100 million years. In terms of chimaeroid paleobiology, this fossil occurrence provides clear evidence that the basic reproductive mode of the group has been highly conserved throughout at least the last ca. 200 million years of chimaeroid history.