The evolution and extinction of the ichthyosaurs from the perspective of quantitative ecospace modelling

Dick, Daniel G.; Maxwell, Erin E.

doi:10.1098/rsbl.2015.0339

Cited by 31 publications

(50 citation statements)

References 16 publications

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“…This grade may be divided into two subgrades: the earlier, Middle Triassic Cymbospondylus-Mixosaurus group, and the Middle-Late Triassic Shastasaurus-Shonisaurus group. The former group includes taxa that represent the early ecological diversification of ichthyosaurs, with a broad range of body forms habits, associated with an increase in disparity (Massare 1987;Thorne et al 2011;Fröbisch et al 2013;Dick & Maxwell 2015). This is marked in the above phylogeny by character changes related to the teeth as a potential synapomorphy of Mixosauridae (e.g.…”

Section: Discussion Ichthyosaur Evolution: Clades and Gradesmentioning

confidence: 99%

A new phylogeny of ichthyosaurs (Reptilia: Diapsida)

Moon

2017

Journal of Systematic Palaeontology

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The largest phylogenetic analysis of ichthyosaurs to date is presented, with 114 ingroup taxa coded at species level. Completeness of the taxa included varied from >98% to <2%; ten taxa were removed a priori using Concatabominations, due to incompleteness and taxonomic uncertainty. The data were analysed using three widely used optimisation criteria: maximum parsimony, maximum likelihood, and Bayesian inference; while similar, each criterion produced different topologies, support, and levels of resolution. Maximum parsimony found a well-resolved consensus tree with minor improvement from a posteriori pruning of unstable taxa; however, general support remains low. Tree resolution was reduced more by taxa that lacked codings from phylogenetically important regions of the tree, rather than by those that simply lacked many codings. Resolution present in the most likely tree is poorly supported; sister relationships cannot be confirmed, although similarities are found to the most parsimonious tree. Bayesian inference found poorly resolved consensus trees. While more resolved, an equal-distribution rate prior is significantly worse than the null gammadistribution rate prior for morphological data, but suggests rate heterogeneity across ichthyosaur phylogeny. Tree comparisons under each analytical criterion failed to select a single best tree, however, the Bayesian inference tree with gamma-distribution rate prior is selected as the best tree based on recent analyses showing improved accuracy using this criterion. Unequivocally resolved clades include Ichthyopterygia, Ichthyosauria, Shastasauria, Euichthyosauria, Parvipelvia, and Neoichthyosauria, but with variation in their taxonomic components. Mixosauridae and Ophthalmosauridae are similarly recovered, but their definitions are modified to stem-based definitions to prevent substantial variation of included taxa. Several genera are not monophyletic: Brachypterygius,

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Section: Discussion Ichthyosaur Evolution: Clades and Gradesmentioning

confidence: 99%

A new phylogeny of ichthyosaurs (Reptilia: Diapsida)

Moon

2017

Journal of Systematic Palaeontology

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“…The mass extinction was preceded by a period of extreme climate changes (Friedrich et al 2012)-possibly weakening ecosystems before the final extinction. The extinction of the dinosaurs is therefore an excellent test case of whether lowered ecosystem resilience can catalyze major extinction events, as has been suggested for other mass extinctions (Roopnarine et al 2007;Dick and Maxwell 2015). The lead-up to the extinction of the dinosaurs is of added interest, because it has been suggested that dinosaurs showed a broad-scale global decline in speciation rates through the last 40 Myr of the Cretaceous (Sakamoto et al 2016), challenging the general consensus that there A B C FIGURE 1.…”

Section: Introductionmentioning

confidence: 99%

Multifaceted disparity approach reveals dinosaur herbivory flourished before the end-Cretaceous mass extinction

et al. 2018

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Understanding temporal patterns in biodiversity is an enduring question in paleontology. Compared with studies of taxonomic diversity, long-term perspectives on ecological diversity are rare, particularly in terrestrial systems. Yet ecological diversity is critical for the maintenance of biodiversity, especially during times of major perturbations. Here, we explore the ecological diversity of Cretaceous herbivorous dinosaurs leading up to the K-Pg extinction, using dental and jaw morphological disparity as a proxy. We test the hypothesis that a decline in ecological diversity could have facilitated their rapid extinction 66 Ma. We apply three disparity metrics that together capture different aspects of morphospace occupation and show how this approach is key to understanding patterns of morphological evolution. We find no evidence of declining disparity in herbivorous dinosaurs as a whole—suggesting that dinosaur ecological diversity remained high during the last 10 Myr of their existence. Clades show different disparity trends through the Cretaceous, but none except sauropods exhibits a long-term decline. Herbivorous dinosaurs show two disparity peaks characterized by different processes; in the Early Cretaceous by expansion in morphospace and in the Campanian by morphospace packing. These trends were only revealed by using a combination of disparity metrics, demonstrating how this approach can offer novel insights into macroevolutionary processes underlying patterns of disparity and ecological diversity.

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“…species' intrinsic characteristics that directly influence their ecological role 32 ). The few studies that have used this or similar approaches have focused specifically on the ecological consequences of the extinction of invertebrates 24,[33][34][35] (but see 37 ). These organisms have important ecological roles, but are usually small-sized, occupy low trophic levels, and tend to be highly speciose.…”

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confidence: 99%

The Pliocene marine megafauna extinction and its impact on functional diversity

et al. 2017

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The end of the Pliocene marked the beginning of a period of great climatic variability and sea-level oscillations. Here, based on a new analysis of the fossil record, we identify a previously unrecognized extinction event among marine megafauna (mammals, seabirds, turtles and sharks) during this time, with extinction rates three times higher than in the rest of the Cenozoic, and with 36% of Pliocene genera failing to survive into the Pleistocene. To gauge the potential consequences of this event for ecosystem functioning, we evaluate its impacts on functional diversity, focusing on the 86% of the megafauna genera that are associated with coastal habitats. Seven (14%) coastal functional entities (unique trait combinations) disappeared, along with 17% of functional richness (volume of the functional space). The origination of new genera during the Pleistocene created new functional entities and contributed to a functional shift of 21%, but minimally compensated for the functional space lost. Reconstructions show that from the late Pliocene onwards, the global area of the neritic zone significantly diminished and exhibited amplified fluctuations. We hypothesize that the abrupt loss of productive coastal habitats, potentially acting alongside oceanographic alterations, was a key extinction driver. The importance of area loss is supported by model analyses showing that animals with high energy requirements (homeotherms) were more susceptible to extinction. The extinction event we uncover here demonstrates that marine megafauna were more vulnerable to global environmental changes in the recent geological past than previously thought.

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The evolution and extinction of the ichthyosaurs from the perspective of quantitative ecospace modelling

Cited by 31 publications

References 16 publications

A new phylogeny of ichthyosaurs (Reptilia: Diapsida)

A new phylogeny of ichthyosaurs (Reptilia: Diapsida)

Multifaceted disparity approach reveals dinosaur herbivory flourished before the end-Cretaceous mass extinction

The Pliocene marine megafauna extinction and its impact on functional diversity

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