Elasmosaurid phylogeny and paleobiogeography, with a reappraisal of <i>Aphrosaurus furlongi</i> from the Maastrichtian of the Moreno Formation

O'gorman, Jose Patricio

doi:10.1080/02724634.2019.1692025

Cited by 26 publications

(69 citation statements)

References 58 publications

(3 reference statements)

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“…Their posterior margins form a deep embayment on each side. This is similar to the condition in Aphrosaurus ( O’Gorman, 2020 ), but is unlike that of Futabasaurus ( Sato, Hasegawa & Manabe, 2006 : fig. 7), which has a broad sheet of bone intersecting between the wings and the midline of the arch.…”

Section: Resultssupporting

confidence: 70%

“…This keel is thickest in the centre of the element but tapers anteriorly and posteriorly. Similar keels are absent in Aphrosaurus ( Welles, 1943 ; O’Gorman, 2020 ) and Futabasaurus ( Sato, Hasegawa & Manabe, 2006 ), or weakly-developed in Morenosaurus ( Welles, 1943 ) and prominent in Albertonectes ( Kubo, Mitchell & Henderson, 2012 ), Thalassomedon ( Welles, 1943 ), TMM 42245-1 ( Storrs, 1981 ), and TTU P 9217 ( Chatterjee & Small, 1989 ). Each wing of the clavicular arch has a smooth ventral surface and appears to lack a distinct facet for the scapula ( Fig.…”

Section: Resultsmentioning

confidence: 94%

“…However, it differs from the clavicular arches of Aphrosaurus ( Welles, 1943 : fig. 23b; O’Gorman, 2020 : figs. 6a–6c) and Futabasaurus ( Sato, Hasegawa & Manabe, 2006 : fig.…”

Section: Resultsmentioning

confidence: 99%

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A new elasmosaurid (Sauropterygia: Plesiosauria) from the non-marine to paralic Dinosaur Park Formation of southern Alberta, Canada

Campbell

Mitchell

Ryan

et al. 2021

PeerJ

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Elasmosaurid plesiosaurian remains have been documented from non-marine to paralic (fluvial to estuarine) sediments of the upper Campanian Dinosaur Park Formation (DPF) of southern Alberta since 1898. Despite this long collection history, this material has received relatively little research attention, largely due to the highly fragmentary nature of most recovered specimens. However, this assemblage is significant, as it constitutes a rare occurrence of plesiosaurian remains in a non-marine depositional environment. This study reports on a recently collected and prepared specimen, which represents the most complete elasmosaurid yet collected from the DPF. This specimen preserves the trunk region, the base of the neck and tail, a partial fore and hind limb, and tooth, and is sufficiently complete to be assigned as the holotype of a new genus and species. This new taxon is diagnosed by a distinctive character state combination including a boomerang-shaped clavicular arch with acute anterior process, convex anterolateral margin, deeply embayed posterior margin, and pronounced ventral keel, together with the presence of 22 dorsal vertebrae, and the anterior dorsal centra bearing a ventral notch. The DPF plesiosaurian fossils were recovered from both estuarine/bay and fluvial palaeochannel sediments. The holotype skeleton represents an osteologically mature individual with an estimated body length of around 5 m, although the largest referred DPF elasmosaurid might have been closer to 7 m, which is considerably larger than other plesiosaurians reported from non-marine deposits. This suggests small-body lengths relative to typical elasmosaurids from marine settings, but is consistent with other plesiosaurians recovered from non-marine sediments. The identification of a distinct elasmosaurid taxon in the DPF might be evidence of niche-partitioning among the predominantly oceanic members of the ubiquitous plesiosaurian clade.

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Section: Resultssupporting

confidence: 70%

Section: Resultsmentioning

confidence: 94%

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A new elasmosaurid (Sauropterygia: Plesiosauria) from the non-marine to paralic Dinosaur Park Formation of southern Alberta, Canada

Campbell

Mitchell

Ryan

et al. 2021

PeerJ

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“…This profound alteration of evolutionary dynamics probably resulted from the equally-profound changes in the structure of marine ecosystems that took place during the earliest Late Cretaceous. Indeed, several groups of cephalopods declined and ichthyosaurs went extinct, possibly as a consequence of environmental volatility 16,[68][69][70] , while mosasauroids, elasmosaurids, teleosts, and selachians abruptly radiated [71][72][73][74][75][76][77] , among other biotic and climatic events e.g. 78 .…”

Section: Discussionmentioning

confidence: 99%

“…Pliosaurids became extinct at or close to the Turonian-Coniacian boundary 79 , 80 , concomitant with the radiation of large-bodied mosasauroids 72 , 79 . Evolving in ichthyosaur-free but shark- and mosasauroid-packed oceans, Late Cretaceous plesiosaurians colonised new regions of the morphospace, possibly filling the gap(s) left by the demise of ichthyosaurs and diversifying the long-necked body plan 77 , 81 , 82 . This suggests that restructuring of the upper levels of oceanic ecosystems by the beginning of the Late Cretaceous fundamentally altered the macroevolutionary landscape of plesiosaurians.…”

Section: Discussionmentioning

confidence: 99%

The macroevolutionary landscape of short-necked plesiosaurians

Fischer

Maclaren

Soul

et al. 2020

Sci Rep

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Throughout their evolution, tetrapods have repeatedly colonised a series of ecological niches in marine ecosystems, producing textbook examples of convergent evolution. However, this evolutionary phenomenon has typically been assessed qualitatively and in broad-brush frameworks that imply simplistic macroevolutionary landscapes. We establish a protocol to visualize the density of trait space occupancy and thoroughly test for the existence of macroevolutionary landscapes. We apply this protocol to a new phenotypic dataset describing the morphology of short-necked plesiosaurians, a major component of the Mesozoic marine food webs (ca. 201 to 66 Mya). Plesiosaurians evolved this body plan multiple times during their 135-million-year history, making them an ideal test case for the existence of macroevolutionary landscapes. We find ample evidence for a bimodal craniodental macroevolutionary landscape separating latirostrines from longirostrine taxa, providing the first phylogenetically-explicit quantitative assessment of trophic diversity in extinct marine reptiles. This bimodal pattern was established as early as the Middle Jurassic and was maintained in evolutionary patterns of short-necked plesiosaurians until a Late Cretaceous (Turonian) collapse to a unimodal landscape comprising longirostrine forms with novel morphologies. This study highlights the potential of severe environmental perturbations to profoundly alter the macroevolutionary dynamics of animals occupying the top of food chains.

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