plastron

(redirected from plastral)
Also found in: Dictionary, Thesaurus, Medical.

plastron

[′plas‚trän]
(invertebrate zoology)
The ventral plate of the cephalothorax of spiders.
(vertebrate zoology)
The ventral portion of the shell of tortoises and turtles.
References in periodicals archive ?
The taxon from Boutersem differs from Borkenia Schleich, 1994 (a possible junior synonym of Palaeoemys sensu Claude and Tong, 2004), from the middle Eocene of Germany, because that form has a well-developed medial keel; its anterior plastral lobe is markedly trapezoidal; and the humero-pectoral sulcus is located at a posterior position (Claude and Tong, 2004; Hervet, 2004a).
The diagnosis for both Cuvierichelys and Landreatchelys proposed by Hervet (2004a) indicated that both taxa lacked well-developed keels in the carapace, but that they could have a poorly-developed posterior medial keel; moderately wide first vertebral, as wide as or wider than the nuchal plate; sub-straight or slightly curved lateral margins of the first vertebral scute; subtrapezoidal anterior plastral lobe, with rounded lateral margins; gulars not overlying the anterior region of the entoplastron, or showing a short overlap.
Characters, that could also be justified by individual variability are, among others: the width of the first vertebral scute in relation to that of the nuchal plate, morphology of posterior margin of the fifth vertebral scute and overlap on the posterior margin of the second suprapygal and anterior margin of the pygal, more rectilinear or more rounded morphology of the anterior plastral lobe.
However, it differs from Thalassemys due to numerous characters, including: the presence of very wide fontanelles between the costal and peripheral plates, with the free region of the dorsal ribs being very wide relative to the width of these plates, especially the last pairs of costals; absence of the carapace cordiform morphology characteristic of Thalassemys; very wide vertebral scutes; different morphology of the preserved suprapygal; much robust and higher plastral buttresses.
Characters such as, among others, its larger size, the absence of lateral plastral fontanelles and the more developed plastral buttresses allows Enaliochelys chelonia to be differentiated from the eurysternids.
The interanal plastral seam is shorter than the interhumeral seam.
heliostemma); the interfemoral plastral seam longest (as in B.
Santee: one nuchal, one neural, nine coastal fragments, six peripherals, three epiplastra, one left xiphiplastron, four plastral fragments, UNSM 56964, 56965.
Devils Nest: one costal fragment, one entoplastron, two plastral fragments, one osteoderm, UNSM 56908.
The development of a plastral concavity in males may result in intersexual differences in relative plastron length (Lovich et al.
According WEEMS (1988) the Allopleuroninae can be defined as large, relatively very thin-shelled, strongly fontanellized sea turtles having strongly reduced, anteroposteriorly elongate plastral elements, a deeply excavated nuchal element, but no development of dermochelyid epithecal shell.