Extinction of fish-shaped marine reptiles associated with reduced evolutionary rates and global environmental volatility

Abstract

Despite their profound adaptations to the aquatic realm and their apparent success throughout the Triassic and the Jurassic, ichthyosaurs became extinct roughly 30 million years before the end-Cretaceous mass extinction. Current hypotheses for this early demise involve relatively minor biotic events, but are at odds with recent understanding of the ichthyosaur fossil record. Here, we show that ichthyosaurs maintained high but diminishing richness and disparity throughout the Early Cretaceous. The last ichthyosaurs are characterized by reduced rates of origination and phenotypic evolution and their elevated extinction rates correlate with increased environmental volatility. In addition, we find that ichthyosaurs suffered from a profound Early Cenomanian extinction that reduced their ecological diversity, likely contributing to their final extinction at the end of the Cenomanian. Our results support a growing body of evidence revealing that global environmental change resulted in a major, temporally staggered turnover event that profoundly reorganized marine ecosystems during the Cenomanian.

Restos apendiculares de un ictiosaurio oftalmosáurido del Barremiano inferior de Villa de Leiva, Colombia

“…Al comparar la morfología de FCG-CBP-87 con los caracteres utilizados por Fischer et al (2016) en su análisis filogenético de los ictiosaurios, se encuentra que 16 de los 21 caracteres relacionados con las aletas anteriores pueden ser establecidos confiablemente en FCG-CBP-87 en los siguientes estados: 57(0), 58(0), 60(2), 61(0), 62(0), 64(1), 65(0), 67(1), 68(1), 69(2), 70(2), 71(0), 72(1), 73(1), 74(1), y 76(1). La comparación de estos caracteres muestra que los rasgos de FCG-CBP-87 corresponden a una morfología apendicular derivada dentro de los oftalmosáuridos y que FCG-CBP-87 comparte caracteres derivados en mayor medida con Platypterygius y Caypullisaurus.…”

“…P. ochevi y P. campylodon son considerados como species inquirenda por Fischer et al (2016). (Maxwell y Caldwell, 2006a;Maxwell y Caldwell, 2006b;Maxwell, 2010;Druckenmiller y Maxwell, 2010;Fischer et al, 2011a;Fernández y Maxwell, 2012;Druckenmiller et al, 2012;Fischer, 2012;Fischer et al, 2012;Roberts et al, 2014;Fischer et al, 2014a;Fischer et al, 2014b;Ji et al, 2016;Paparella et al, 2017;Maxwell et al, 2016;Fischer et al, 2016). Un panorama de estos aportes, con sus respectivas referencias, se expone sintéticamente en la revisión de las ocurrencias de especímenes de oftalmosáuridos presentada por Fernández y Campos (2015).…”

“…Un panorama de estos aportes, con sus respectivas referencias, se expone sintéticamente en la revisión de las ocurrencias de especímenes de oftalmosáuridos presentada por Fernández y Campos (2015). Dentro de la familia Ophthalmosauridae se reconocen actualmente 19 géneros, muchos de ellos monoespecíficos y representados sólo por su holotipo, de edades que comprenden desde el Jurásico medio (Bajociano) hasta el Cretácico superior (Cenomaniano) (Fernández y Campos, 2015;Fischer et al, 2016). En Ophthalmosauridae se incluyen numerosos especímenes de Europa y otros no tan abundantes de Norteamérica, Centroamérica, Suramérica y Australia (Fernández y Campos, 2015;Fischer et al, 2016).…”

How giant marine reptiles terrorized the ancient seas

“…It turns out that the fish-shaped reptiles called parvipelvians, the only group of ichthyosaurs to endure from the Triassic into the Cretaceous, had a greater range of shapes during the middle of the early Cretaceous than at any other time in their history 8 . "The diversity of ichthyosaurs in the Cretaceous, in particular, is even higher than we ever thought it was", says Fischer's co-author Darren Naish, a vertebrate palaeontologist at the University of Southampton, UK.…”

Isolated pliosaurid teeth from the Albian–Cenomanian (Cretaceous) of Annopol, Poland

“…In Europe, it is dominated by isolated teeth known from numerous localities (e.g. Owen 1851;Papazzoni 2003;Marcinowski and Radwański 1983;Kear et al 2014;Bardet et al 2016;Fischer et al 2016;Madzia 2016;Sachs et al 2017). In most cases, the material was attributed to the taxon Polyptychodon Owen, 1841a.…”