New Mexico Geological Society Annual Spring Meeting — Abstracts

A new ichnospecies of Cardioichnus is documented and proposed from the Mesilla Valley Formation, Cerro de Cristo Rey, southern NM. Invertebrate trace fossils are common in these shallow marine strata of Cretaceous (late Albian) age. One bioclastic wackestone/packstone in this formation contains many specimens of Cardioichnus. The proposed ichnospecies is a heart-shaped resting trace (cubichnia) with a bilobate terminus, and is preserved exclusively in convex epirelief. It differs from described ichnospecies of Cardioichnus in its preservation, geometry, implied behavior, and host sediment. Several specimens are also associated with Scolicia burrows. The tracemaker is a spatangoid echinoid, most likely Heteraster d'Orbigny, 1853, which has been described from this formation. This is a part of an ongoing study of trace fossils from Albian strata at Cerro de Cristo Rey in southern New Mexico.