First record of Polycotylidae (Sauropterygia, plesiosauria) from the Upper Cretaceous of Antarctica

Novas, Fernando E.; D'angelo, Julia Soledad; O'gorman, Jose Patricio; Agnolín, Federico; Lirio, Juan Manuel; Isasi, Marcelo P.

doi:10.1016/j.cretres.2015.06.015

Cited by 21 publications

(13 citation statements)

References 38 publications

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“…Such extra-formational clasts typically occur as strings and thin lenses in the lower DPF ( Eberth & Hamblin, 1993 ). However, we interpreted the pebbles associated with TMP 2009.037.0068/1990.046.0001/.0002 as gastroliths, which frequently occur in association with elasmosaurid remains ( Kubo, Mitchell & Henderson, 2012 ; O’Gorman, Olivero & Cabrera, 2012 ; O’Gorman et al, 2013 ; Hiller, O’Gorman & Otero, 2014 ), as well as more rarely with polycotylids ( Sato & Storrs, 2000 ; Schmeisser & Gillette, 2009 ; Novas et al, 2015 ), leptocleidids ( Kear, Schroeder & Lee, 2006 ), and cryptoclidids ( Kear, 2006 ). Gastroliths were concentrated near the pectoral girdle and around the other larger skeletal elements of TMP 2009.037.0068/1990.046.0001/.0002.…”

Section: Resultsmentioning

confidence: 99%

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: Resultsmentioning

confidence: 99%

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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“…The origin of the least inclusive clade formed by Russellosaurina and Mosasaurinae (+ Halisaurinae) occurred ∼100 Mya, and the splitting of the clade uniting plioplatecarpines and tylosaurines ∼93 Mya; thus covering the last few millions of years of the brachauchenine evolution. In turn, during the splitting of the smallest clade comprising globidensins and mosasaurins (∼81 Mya) and the origin of the Mosasaurus node (∼75 Mya), pliosaurids were probably already extinct and polycotylids rare (e.g., Sato, 2005;Salgado, Parras & Gasparini, 2007;O'Gorman & Gasparini, 2013;Novas et al, 2015;Fischer et al, 2018;Morgan & O'Keefe, 2019).…”

Section: Rates Of Morphological Evolutionmentioning

confidence: 99%

Estimating the evolutionary rates in mosasauroids and plesiosaurs: discussion of niche occupation in Late Cretaceous seas

Madzia

Cau²

2020

PeerJ

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Observations of temporal overlap of niche occupation among Late Cretaceous marine amniotes suggest that the rise and diversification of mosasauroid squamates might have been influenced by competition with or disappearance of some plesiosaur taxa. We discuss that hypothesis through comparisons of the rates of morphological evolution of mosasauroids throughout their evolutionary history with those inferred for contemporary plesiosaur clades. We used expanded versions of two species-level phylogenetic datasets of both these groups, updated them with stratigraphic information, and analyzed using the Bayesian inference to estimate the rates of divergence for each clade. The oscillations in evolutionary rates of the mosasauroid and plesiosaur lineages that overlapped in time and space were then used as a baseline for discussion and comparisons of traits that can affect the shape of the niche structures of aquatic amniotes, such as tooth morphologies, body size, swimming abilities, metabolism, and reproduction. Only two groups of plesiosaurs are considered to be possible niche competitors of mosasauroids: the brachauchenine pliosaurids and the polycotylid leptocleidians. However, direct evidence for interactions between mosasauroids and plesiosaurs is scarce and limited only to large mosasauroids as the predators/scavengers and polycotylids as their prey. The first mosasauroids differed from contemporary plesiosaurs in certain aspects of all discussed traits and no evidence suggests that early representatives of Mosasauroidea diversified after competitions with plesiosaurs. Nevertheless, some mosasauroids, such as tylosaurines, might have seized the opportunity and occupied the niche previously inhabited by brachauchenines, around or immediately after they became extinct, and by polycotylids that decreased their phylogenetic diversity and disparity around the time the large-sized tylosaurines started to flourish.

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“…Position within the axial skeleton -Given the limited number of polycotylid vertebrae described and discussed (see e.g. Novas et al 2015) and no reported polycotylids from the Maastricht formation so far, our discussion on the attribution of position in the axial skeleton has been focused on what has been discussed for the Elasmosauridae. In vertebral centra of elasmosaurs, those features that allow determination of the position within the axial skeleton are subject to both intraspecific and ontogenetic variations (O'Keefe & Hiller, 2006, pp.…”

Section: Discussionmentioning

confidence: 99%

New plesiosaurid material from the Maastrichtian type area, the Netherlands

Miedema

Schulp

Jagt

et al. 2019

Netherlands Journal of Geosciences

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Here we report on a newly collected, well-preserved vertebral centrum of a plesiosaur from the type area of the Maastrichtian Stage in southern Limburg. The specimen is interpreted as a caudal vertebra that originated from an osteologically immature or juvenile individual, as evidenced by the position of the pedicular facets, the presence of a notochord pit and the absence of fused neural arches. It adds to the meagre record of sauropterygians in the area.

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First record of Polycotylidae (Sauropterygia, plesiosauria) from the Upper Cretaceous of Antarctica

Cited by 21 publications

References 38 publications

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

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

Estimating the evolutionary rates in mosasauroids and plesiosaurs: discussion of niche occupation in Late Cretaceous seas

New plesiosaurid material from the Maastrichtian type area, the Netherlands

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