The Occurrence of Twin Embryos, Abnormal Morphologies and Test Repair in Lower Cretaceous Orbitolinidae (Larger Benthic Foraminifera): Examples From France, Somalia, Iran, Tibet, and Texas

Abstract

Specimens displaying unusual ( " abnormal " or aberrant) test morphologies, for example, the presence of twin embryos, or test repair after damage, are reported from Lower Cretaceous Orbitolinidae. Twin embryos (which have not always been recognized as such in the literature) are described from the upper Barremian of Tibet and France (Palorbitolina lenticularis), the upper Albian of Somalia (Orbitolina gr. sefini), and the upper Aptian-early Albian of Texas (e.g., Mesorbitolina texana). Twin embryos have so far only been reported from the Orbitolininae (with complex embryo), and not from the Dictyoconinae (with simple embryo). Repaired partially damaged tests (the damage possibly caused by predation or mechanical fracture) are observed in lower Aptian orbitolinids from Iran. Regeneration after damage (bioadjustment) leads to malformed tests.