Preprint on PeerJ

At the time of writing, this paper is available as a PeerJ Preprints, which has not yet been peer-reviewed (though the manuscript has been submitted for formal review):

  • Taylor, Michael P. 2017. Xenoposeidon is the earliest known rebbachisaurid sauropod dinosaur. PeerJ PrePrints 5:e3415. doi: 10.7287/peerj.preprints.3415 [PDF] [PeerJ page]

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High-resolution figures

Figure 1. NHMUK R2095, the holotype and only vertebra of Xenoposeidon proneneukos, shown from all six cardinal directions. Top row: A. dorsal view, with anterior to the left. Middle row, left to right: B. anterior, C. left lateral, D. posterior and E. right lateral view. Bottom row: F. ventral view, with anterior to the left. Scale bar = 200 mm.

Figure 2. NHMUK R2095, the holotype and only vertebra of Xenoposeidon proneneukos, in left lateral view, with interpretative drawing. A. The incorrect interpretation of the laminae from Taylor and Naish (2017:figure 4A), with identifying captions greyed out since they are largely incorrect. B. The revised interpretation of the same laminae, based on the similar arrangement in Rebbachisaurus garasbae. Scale bar = 200 mm.

Figure 3. Centra and neural arches of posterior dorsal vertebrae from two rebbachisaurid sauropods (not to scale), highlighting the distinctive “M” shape formed by laminae high on the neural arch. A. NHMUK R2095, the holotype and only vertebra of Xenoposeidon proneneukos. B. MNHN MRS 1958, a posterior dorsal vertebra from the holotype specimen of Rebbachisaurus garasbae.

Figure 4. NHMUK R2095, the holotype and only vertebra of Xenoposeidon proneneukos, in left lateral view, interpreted as a rebbachisaurid. This interpretation is modelled primarily on MNHN MRS 1958, a posterior dorsal vertebra from the holotype specimen of Rebbachisaurus garasbae. The CPOL passes through a sheetlike PCDL, as in Rebbachisaurus; but the lateral CPRL forms a cross-shaped junction with the ACPL, each of these laminae equally interrupting the trajectory of the other. Abbreviations as used in the text. Scale bar = 200 mm.

Figure 5. NHMUK R2095, the holotype and only vertebra of Xenoposeidon proneneukos, in left anteroventrolateral view, highlighting the three sets of laminae related to the prezygapophyses. The trajectories of the medial CPRLs (which emerge from the neural arch pedicels) and the lateral CPRLs (which intersect with the APCLs) indicate the approximate position of the prezygapophyses. The additional arched laminae form the margins of the large, teardrop-shaped CPRF, but meet at a position some way below and posterior to the presumed location of the prezygapophyseal facets. Breakage of both medial CPRLs and the left ACPL and PCDL is indicated by cross-hatching. Note that, from this perspective, the lateral CPRL appears to turn a corner where it intersects with the ACPL, such that the posteroventral portion of the lateral CPRL appears contiguous with the dorsal portion of the ACPL. This is an illusion brought about by the eminence at the point of intersection. As always, this is much easier to see in three dimensions. Abbreviations as used in the text.

Supplementary file

Supplementary file 1. Three-dimensional surface model (11 million polygons) of NHMUK R2095, the holotype and only vertebra of Xenoposeidon proneneukos. A 3D polygon mesh file was created by Heinrich Mallison in Agisoft Photoscan Pro version 1.3.0 (agisoft.com), from 95 high resolution digital photographs by the author. All 95 images aligned, and resulted in a dense point cloud at maximum resolution of 20,900,043 points and 44,871,128 polygons. Scaling was based on a single 10 cm scale bar created from a high quality scale bar placed in the pictures with the specimen. Available from https://doi.org/10.6084/m9.figshare.5605612.v2 and viewable online at https://sketchfab.com/models/7f88203e0bbb49a194cb254ab05c4b22

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