The collapse of a compressed elastic tube conveying a flow occurs in several physiological applications and hence becomes a problem of considerable interest.
The record of Zapalasaurus bonapartei shows that, at least in the Neuquina Basin, basal diplodocoids were more diverse than previously thought.
Zapalasaurus bonapartei is considered as the sister group of the other diplodocoids (excluding Haplocanthosaurus).ĭiplodocoids were abundant in the Early Cretaceous, becoming extinct by the early Late Cretaceous. Uniting the prezygapophysis and the zygapophyseal portion of the postzygodiapophyseal lamina, cervical vertebrae with the diapophyseal portion of the postzygodiapophyseal lamina reduced, cervical vertebrae with poorly developed spinoprezygapophyseal laminae, mid and posterior caudal vertebrae with anteroposteriorly elongated neural spines, whose anterodorsal corners are higher than their posterodorsal ones, and caudal centrum Several characters are interpreted as autapomorphies of Zapalasaurus bonapartei: cervical vertebrae. The unit that yielded the holotype of this dinosaur is the Piedra Parada Member of the La Amarga Formation, whose age is regarded as Barremian-lower Aptian. View full-textĪn incomplete skeleton from Puesto Morales (Neuquén Province, Argentina) is described as a new species of sauropod, Zapalasaurus bonapartei. A discussion is presented about the morphology and ecology of this taxon in the light of pertinent literature. The new taxon is circumneutral to acidophilous and oligo- to mesotraphentic. producing a cruciform shape, the new species is distinguished by the tapering and narrowly rounded apices and the much higher stria density. However, the taxon also exhibits unique features that justify its separation at the species level from any currently known taxon within Fragilariforma: 1) the spines are subtended by a siliceous ring having short extensions projecting onto the valve face, 2) there is a portula lacking a labiate internal structure, and 3) the girdle bands lack perforations. spines on the costae at the valve face/mantle junction, a portula along a stria, developed apical pore fields, and ligulate, open girdle bands. Williams & Round such as uniseriate striae recessed between thickened costae, simple round areolae. Light (LM) and scanning electron microscopy (SEM) data reveal that the taxon has several features congruent with taxa currently placed in Fragilariforma D. Morales, Manoylov & Bahls, is described from rivers in the northern United States of America. A new taxon, namely Fragilariforma horstii E.
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