Even though Neogene outcrops along the temperate Pacific coast of South America harbor a rich marine vertebrate fossil record, no studies have examined the diversification patterns of these taxa. Here, we analyze diversification trends based on the stratigraphic ranges of 86 genera of marine vertebrates, including sharks, rays, chimaeras, marine mammals, and seabirds. The richness of genera shows a hump-shaped trend, with maximum values around the late Miocene, driven by a large pulse of origination during mid-Miocene and higher extinction rates during the Pliocene. Trends varied markedly among taxa and departed largely from expectations based on global diversification patterns. Moreover, these trends cannot be explained solely as a sampling artifact derived from sampling intensity (i.e., number of occurrences) or sedimentary rock availably (i.e., number of geologic maps). A large fraction of genera (42%) went globally extinct by the late Pliocene–Pleistocene, and the extinction was highly selective according to different ecological and life-history traits. An analysis using “randomForest” showed that taxonomic structure and the geographic midpoint of distribution could explain up to 83% of extinction of genera. The extinction was taxonomically clumped (i.e., disproportionally high in Cetacea and very low in Carcharhiniformes) and concentrated in the northern area of the temperate Pacific coast of South America. Our results suggest that the particular paleogeographic, paleoclimatic, and paleoceanographic events that took place during the Neogene along the temperate Pacific coast of South America had a significant effect on the structure of marine biodiversity.

Aim To evaluate the existence of a latitudinal gradient of richness (LGR) in rocky intertidal gastropods and the role of evolutionary processes in shaping the LGR. Location The entire eastern Pacific coast, from Alaska to Tierra del Fuego, encompassing ca. 120° latitude. Methods The LGR was assessed using field surveys and a comprehensive literature dataset from 308 rocky intertidal sites, representing 328 species and 159 genera. The importance of geographic patterns of diversification in shaping the LGR was assessed using three complementary approaches. First, we used the fossil record to evaluate the region of origination of genera (tropical vs. extra‐tropical). Secondly, we used a nestedness analysis to compare present‐day biogeographic distributions of genera with their region of origin. Finally, we evaluated the importance of biogeographic dynamics for shaping the LGR using a projection matrix and estimating transition probabilities among different biogeographic states. Results Eastern Pacific rocky intertidal gastropods follow the canonical latitudinal gradient of richness (higher richness in the tropics). Originations were similar in the tropics and extra‐tropics, a pattern that was robust to geographic differences in fossil sampling. The biogeographic distribution of genera was significantly nested, irrespective of the region of origin of genera. The distribution dynamics model accurately reproduced the LGR and showed that key‐transitions are low extinction in the tropics and high dispersal of taxa from the extra‐tropics to the tropics. Conclusions The existence of a canonical LGR in rocky intertidal gastropods can be explained by the combined effect of reduced extinction rates in the tropics and the range expansion of taxa from the extra‐tropics toward the tropics, in what we have called the ‘into the tropical museum’ hypothesis.

The environmental transformations that occurred during the Neogene had profound effects on spatiotemporal biodiversity patterns, yet the modulating role of traits (i.e., physiological, ecological, and life-history traits) remains little understood. We tested this idea using the Neogene fossil record of chondrichthyans along the temperate Pacific coast of South America (TPSA). Information for georeferenced occurrences and ecological and life-history information of 38 chondrichthyan fossil genera in 42 Neogene sites was collected. Global georeferenced records were used to estimate present-day biogeographic distributions of the genera and to characterize the range of oceanographic conditions in which each genus lives as a proxy of their realized niche. Biogeographic range shifts (Neogene–present) were evaluated at regional and local scales. The role of traits as drivers of different range dynamics was evaluated using random forest models. The magnitude and direction of biogeographic range shifts were different at both spatial scales. At a regional scale, 34% of genera contracted their ranges, disappearing from the TPSA. At a local scale, a similar proportion of genera expanded and contracted their southern endpoints of distribution. The models showed a high precision at both spatial scales of analyses, but the relative importance of predictor variables differed. At a regional scale, disappearing genera tended to have a higher tolerance to salinity, lower sea surface temperature (SST) range, and smaller body sizes. At a local scale, genera contracting their ranges tended to live at greater depths, tolerate lower levels of primary productivity, and show a reduced tolerance to higher and lower SST ranges. The magnitude and direction of the changes in the range distribution were scale dependent and variable across the genera. Hence, multiple environmental exogenous factors interacted with taxon traits during the Neogene, creating a mosaic of biogeographic dynamics.

†Pycnodontiformes was a successful lineage of primarily marine fishes that broadly diversified during the Mesozoic. They possessed a wide variety of body shapes and were adapted to a broad range of food sources. Two other neopterygian clades possessing similar ecological adaptations in both body morphology (†Dapediiformes) and dentition (Ginglymodi) also occurred in Mesozoic seas. Although these groups occupied the same marine ecosystems, the role that competitive exclusion and niche partitioning played in their ability to survive alongside each other remains unknown. Using geometric morphometrics on both the lower jaw (as constraint for feeding adaptation) and body shape (as constraint for habitat adaptation), we show that while dapediiforms and ginglymodians occupy similar lower jaw morphospace, pycnodontiforms are completely separate. Separation also occurs between the clades in body shape so that competition reduction between pycnodontiforms and the other two clades would have resulted in niche partitioning. Competition within pycnodontiforms seemingly was reduced further by evolving different feeding strategies as shown by disparate jaw shapes that also indicate high levels of plasticity. Acanthomorpha was a teleostean clade that evolved later in the Mesozoic and which has been regarded as implicated in driving the pycnodontiforms to extinction. Although they share similar body shapes, no coeval acanthomorphs had similar jaw shapes or dentitions for dealing with hard prey like pycnodontiforms do and so their success being a factor in pycnodontiform extinction is unlikely. Sea surface temperature and eustatic variations also had no impact on pycnodontiform diversity patterns according to our results. Conversely, the occurrence and number of available reefs and hardgrounds as habitats through time seems to be the main factor in pycnodontiform success. Decline in such habitats during the Late Cretaceous and Palaeogene might have had deleterious consequences for pycnodontiform diversity. Acanthomorphs occupied the niches of pycnodontiforms during the terminal phase of their existence.