page_title: Dreadnoughtus
section_title: Distinctive features
hierarchical_section_title: Dreadnoughtus / Description / Distinctive features
caption_attribution_description: English: Dreadnoughtus Tail Composite Image (by Kenneth Lacovara)
context_page_description: Dreadnoughtus is a genus of titanosaurian sauropod dinosaur containing a single species, Dreadnoughtus schrani. D. schrani is known from two partial skeletons discovered in Upper Cretaceous rocks of the Cerro Fortaleza Formation in Santa Cruz Province, Argentina. It is one of the largest terrestrial vertebrates known, possessing the greatest mass of any land animal that can be calculated with reasonable certainty. D. schrani is known from a more complete skeleton than any other gigantic titanosaurian.
  Drexel University paleontologist Kenneth Lacovara, who discovered the species, chose the name Dreadnoughtus, which means “fears nothing," stating “I think it’s time the herbivores get their due for being the toughest creatures in an environment."
context_section_description: The tail of Dreadnoughtus schrani has several characteristic features included in the diagnosis of the species. The first vertebra of the tail has a ridge on its ventral surface called a keel. In the first third of the tail, the bases of the neural spines are extensively subdivided into cavities caused by contact with air sacs (part of the dinosaur's respiratory system). In addition, the anterior and posterior boundaries of these neural spines have distinct ridges (pre- and postspinal laminae) connecting them to the pre- and postzygapophyses (the articulation points of the neural arches). In the middle of its tail, the vertebrae have a triangular process that extends over the centrum towards each preceding vertebra.
  Just like modern archosaurs with tails (crocodilians, for example), D. schrani had bones below the vertebrae called chevrons or haemel arches. These bones connect with the ventral surface of the vertebrae and are “Y” shaped when viewed anteriorly. In Dreadnoughtus schrani the bottom stem of the “Y” is broadly expanded, likely for the attachment of muscles.
  The shoulder girdle and forelimb of D. schrani also exhibit unique features. An oblique ridge crosses the interior face of the scapular blade, extending from the top side near the far end of the blade to the bottom side near the base of the scapular blade. Finally, each end of the radius exhibits a unique form: the top, or proximal end, has a distinct concave embayment on its posterior face while the bottom, or distal end, is nearly square in shape instead of broadly expanded.
caption: Composite image of the fossil caudal (tail) vertebrae
exif: {"Image ImageWidth": "27300", "Image ImageLength": "7500", "Image BitsPerSample": "[8, 8, 8]", "Image PhotometricInterpretation": "2", "Image Orientation": "Horizontal (normal)", "Image SamplesPerPixel": "3", "Image XResolution": "300", "Image YResolution": "300", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CC (Macintosh)", "Image DateTime": "2014:08:27 00:18:26", "Image ExifOffset": "232", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "382", "Thumbnail JPEGInterchangeFormatLength": "2199", "EXIF ExifVersion": "0221", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "2730", "EXIF ExifImageLength": "750"}