Late Cretaceous ammonoids show that drivers of diversification are regionally heterogeneous

Palaeontologists have long sought to explain the diversification of individual clades to whole biotas at global scales. Advances in our understanding of the spatial distribution of the fossil record through geological time, however, has demonstrated that global trends in biodiversity were a mosaic of regionally heterogeneous diversification processes. Drivers of diversification must presumably have also displayed regional variation to produce the spatial disparities observed in past taxonomic richness. Here, we analyse the fossil record of ammonoids, pelagic shelled cephalopods, through the Late Cretaceous, characterised by some palaeontologists as an interval of biotic decline prior to their total extinction at the Cretaceous-Paleogene boundary. We regionally subdivide this record to eliminate the impacts of spatial sampling biases and infer regional origination and extinction rates corrected for temporal sampling biases using Bayesian methods. We then model these rates using biotic and abiotic drivers commonly inferred to influence diversification. Ammonoid diversification dynamics and responses to this common set of diversity drivers were regionally heterogeneous, do not support ecological decline, and demonstrate that their global diversification signal is influenced by spatial disparities in sampling effort. These results call into question the feasibility of seeking drivers of diversity at global scales in the fossil record

Late Cretaceous ammonoids show that drivers of diversification are regionally heterogeneous

Palaeontologists have long sought to explain the diversification of individual clades to whole biotas at global scales. Advances in our understanding of the spatial distribution of the fossil record through geological time, however, has demonstrated that global trends in biodiversity were a mosaic of regionally heterogeneous diversification processes. Drivers of diversification must presumably have also displayed regional variation to produce the spatial disparities observed in past taxonomic richness. Here, we analyse the fossil record of ammonoids, pelagic shelled cephalopods, through the Late Cretaceous, characterised by some palaeontologists as an interval of biotic decline prior to their total extinction at the Cretaceous-Paleogene boundary. We regionally subdivide this record to eliminate the impacts of spatial sampling biases and infer regional origination and extinction rates corrected for temporal sampling biases using Bayesian methods. We then model these rates using biotic and abiotic drivers commonly inferred to influence diversification. Ammonoid diversification dynamics and responses to this common set of diversity drivers were regionally heterogeneous, do not support ecological decline, and demonstrate that their global diversification signal is influenced by spatial disparities in sampling effort. These results call into question the feasibility of seeking drivers of diversity at global scales in the fossil record

Data from: Paleoenvironmental and paleobiogeographical implications of a Middle Pleistocene mollusc assemblage from the marine terraces of Baía das Pipas, southwest Angola

Quaternary raised marine terraces containing the remains of diverse, shallow water marine invertebrate faunas are widespread across coastal Angola. These deposits and faunas have not been studied in the same detail as contemporaneous features in northwest and southernmost Africa. We analyzed the fossil assemblages and sedimentology of two closely spaced Middle Pleistocene marine terrace deposits in Baía das Pipas, southwest Angola. This revealed 46 gastropod and 29 bivalve species, along with scleractinian corals, encrusting bryozoans, polychaete tubes, barnacles, and echinoids. The fauna is characteristic of intertidal and nearshore rocky substrates and sandy soft-bottom habitats. Sedimentological analysis is consistent with faunal data and indicates an upper shoreface paleoenvironment along a gravel coast. This diverse fauna stands out as a rare example of a marine Pleistocene assemblage from over 6,000 km of the West African coast. The assemblage is dominated by tropical West African molluscs, including species from the "Senegalese fauna" that colonized northern Africa and beyond during Pleistocene interstadials. Additionally, as along the modern Namibe Desert coast, the influence of the cool-water Benguela Current is apparent in the paleofauna by the occurrence of a few temperate species. The distribution and thermal tolerances of extant species identified in the Pipas fauna indicate that this region experienced similar climatic and oceanographic conditions as that of the present during this interstadial. Seasonal temperature varied between ~20 and 28 ºC and resulted from upwelling in this tropical setting

SUPPLEMENTAL DATA 1

SUPPLEMENTAL DATA

Evolutionary Patterns among Living and Fossil Kogiid Sperm Whales: Evidence from the Neogene of Central America

<div><p>Kogiids are known by two living species, the pygmy and dwarf sperm whale (<i>Kogia breviceps</i> and <i>K</i>. <i>sima</i>). Both are relatively rare, and as their names suggest, they are closely related to the sperm whale, all being characterized by the presence of a spermaceti organ. However, this organ is much reduced in kogiids and may have become functionally different. Here we describe a fossil kogiid from the late Miocene of Panama and we explore the evolutionary history of the group with special attention to this evolutionary reduction. The fossil consists of cranial material from the late Tortonian (~7.5 Ma) Piña facies of the Chagres Formation in Panama. Detailed comparison with other fossil and extant kogiids and the results of a phylogenetic analysis place the Panamanian kogiid, herein named <i>Nanokogia isthmia</i> gen. et sp. nov., as a taxon most closely related to <i>Praekogia cedrosensis</i> from the Messinian (~6 Ma) of Baja California and to <i>Kogia</i> spp. Furthermore our results show that reduction of the spermaceti organ has occurred iteratively in kogiids, once in <i>Thalassocetus antwerpiensis</i> in the early-middle Miocene, and more recently in <i>Kogia</i> spp. Additionally, we estimate the divergence between extant species of <i>Kogia</i> at around the late Pliocene, later than previously predicted by molecular estimates. Finally, comparison of <i>Nanokogia</i> with the coeval <i>Scaphokogia cochlearis</i> from Peru shows that these two species display a greater morphological disparity between them than that observed between the extant members of the group. We hypothesize that this reflects differences in feeding ecologies of the two species, with <i>Nanokogia</i> being more similar to extant <i>Kogia</i>. <i>Nanokogia</i> shows that kogiids have been part of the Neotropical marine mammal communities at least since the late Miocene, and gives us insight into the evolutionary history and origins of one of the rarest groups of living whales.</p></div

SUPPLEMENTAL DATA 2

Excel file containing supplementary materials