Baryonychidae Charig and Milner 1986
Creators: name: Rauhut, Oliver W. M.
Publisher: name: Zenodo
Year: 2003
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Reptilia
Dinosauria
Baryonychidae

description: Baryonychidae Charig and Milner, 1986 <i>Included taxa. Angaturama limai Kellner and Campos, 1996</i>; <i>Baryonyx walkeri</i> Charig and Milner, 1986; <i>Irritator challenged</i> Martill, Cruickshank, Frey, Small and Clark, 1996; <i>Spinosaurus aegyptiacus</i> Stromer, 1915, <i>partim; Suchomimus tenerensis Sereno, Beck, Dutheil, Gado, Larsson, Lyon, Marcot, Rauhut, Sadleir, Sidor, Varricchio, Wilson and Wilson, 1998</i>. <i>Temporal range.</i> Barremian-Cenomanian. <i>Occurrence.</i> Romualdo Member of the Santana Formation, Ceara, Brazil; Upper Weald Clay, Surrey, England; Baharia Formation, Marsa Matruh, Egypt; Elrhaz Formation, Agadez, Niger; Kem Kem beds, Morocco. <i>Diagnosis.</i> Dentary with strongly developed anterior expansion; anterior dentary teeth much larger than the relatively small and closely spaced posterior teeth; medial alveolar border is as high as the lateral border and formed by a sheet of bone of the denary rather than by separately ossified interdental plates; teeth almost round in basal cross section and only slightly recurved; very long premaxillae, forming a rostral rosette; seven premaxillary teeth; ventral margin of premaxilla strongly concave; anterior ramus of maxilla strongly elongated; angle between anterior and ventral ramus of the lacrimal less than 45 degrees; dorsal vertebrae with several small vertical laminae connecting the transverse process with the neural spine dorsally; humerus extremely robust, with strongly expanded internal tuberosity and distal condyles; ulna with a broad and very strongly developed olecranon process; ischium with a long and low obturator flange. <i>Remarks.</i> The family Baryonychidae (Text-fig. 6b) was proposed by Charig and Milner (1986) to include a single species, <i>Baryonyx walkeri.</i> Buffetaut (1989, 1992) noted similarities between the jaws of <i>Baryonyx</i> and the slightly younger <i>Spinosaurus</i> from the Cenomanian of Egypt, and concluded that both animals probably belong to the family Spinosauridae. This view has since been accepted by several authors (e.g. Sereno <i>et al.</i> 1994, 1996, 1998). Although Charig and Milner (1997) retained <i>Baryonyx</i> in its own family, they acknowledged the similarities between this genus and <i>Spinosaurus</i> and united the Baryonychidae and the Spinosauridae in the superfamily Spinosauroidea. The matter is complicated by the problematic status of <i>Spinosaurus aegyptiacus.</i> The holotype of this genus was found in the Baharia Oasis of Egypt at the beginning of the twentieth century and was subsequently described by Stromer (1915). The material consisted of two dentaries, a maxillary fragment, and several vertebrae. The only other accounts of the original specimen were by Stromer (1934 <i>b</i>, 1936), before all the material was destroyed during a bombing raid in 1944. In the introduction to his original description Stromer (1915, p. 3) commented on the association and preservation of the specimen: ‘Many of the bones had already been broken and deformed in the sediment; furthermore, the remains were completely jumbled. The skull seems to have originally been present, but due to its exposed position had been almost completely eroded away. Especially the maxillary fragment shows signs of erosion of an exposed bone; cracks in the posterior ends of the lower jaws and the especially anteriorly eroded cervical vertebrae also indicate a superficial position of the fossils. No parts of the appendicular skeleton were found, indicating that the skeleton was already incomplete when it was covered by sediment. The soft parts had surely decayed before burial, thus allowing the dislocation of the bones. Several teeth, some of them already loosened by erupting replacement teeth, fell out of the jaws, complete with their roots, and all the bones were jumbled, perhaps due to scavengers or water flow. However, given the preservation of fine details and the lack of abrasion, prolonged transport of the bones can be excluded. In the sediment, the fossils suffered from pressure, probably caused by gypsum- and salt-flow rather than by tectonic events. Given their positions in the sediment and their preservation, the remains represent one individual. Only the size of the sacral and caudal vertebrae are problematic in this respect, which will be discussed in the respective descriptions.’ (my translation). Stromer later (1934 <i>b</i>, p. 21) stated that: ‘It remains questionable, if... especially the oversized anterior caudal vertebra n... belongs to <i>Spinosaurus</i> at all.’ (my translation). Judging from Stromer’s illustration (1915, pl. 1, fig. 1a -b) the vertebra in question looks more like an o rn ithischian caudal than a theropodan element. Given this probable mix of taxa in the original type material, it cannot be excluded that the rest of the material also represents more than one taxon. The following points may indicate that the holotype of <i>S. aegyptiacus</i> actually represents a mixture of remains of different theropods: 1. The dentary figured by Stromer (1915, pl. 1, figs 6, 12) agrees with dentaries of <i>Baryonyx</i> and material referred to <i>Suchomimus</i> in almost every detail and shows all the baryonychid synapomorphies listed above. 2. The dorsal vertebrae of the type of <i>Spinosaurus aegyptiacus</i> lack the strong pneumatisation and additional laminae seen in both <i>Baryonyx</i> and <i>Suchomimus.</i> Their principal characters are comparable to those seen in allosauroids, with the exception of the strongly elongated neural spines. Elongated neural spines are present in the carcharodontosaur <i>Acrocanthosaurus,</i> though to a lesser degree than in <i>S. aegyptiacus</i> (Stovall and Langston 1950). Since large carcharodontosaurs are present in Baharia, the vertebrae might represent these animals. 3. The cervical vertebrae figured by Stromer (1915, pl. 2, figs 1-2) differ significantly from the dorsal vertebrae in respect of the height of their neural spines. This difference is so marked that it might be questionable that they belong to the same taxon, although an abrupt change in spine height is present in other high-spined dinosaurs (e.g. <i>Ouranosaurus;</i> Taquet 1976). Given this uncertainty of the association of the holotype material of <i>Spinosaurus aegyptiacus,</i> it seems at present better to use the family name Baryonychidae than the name Spinosauridae until new material becomes available to clarify the status of <i>Spinosaurus.</i> However, the dentary of the type of <i>Spinosaurus</i> can at least be referred to the Baryonychidae. <i>Suchomimus tenerensis</i> from the Aptian of Niger is based on a partial postcranial skeleton (MNN GDF 500) and several referred specimens, including a partial skull (MNN GDF 501; see Sereno <i>et al.</i> 1998). All the material is very similar to <i>Baryonyx,</i> and can thus be referred to the Baryonychidae with certainty. Two baryonychids from South America were described in 1996: <i>Irritator challengeri,</i> based on a skull lacking the anterior part of the snout (SMNS 58022), by Martill <i>et al.,</i> and <i>Angaturama limai,</i> based on the tip of a snout, by Kellner and Campos. <i>Irritator</i> (SMNS 58022) shows the diagnostic angle in the lacrimal, as well as a braincase that is very similar to that of <i>Baryonyx</i> and can, therefore, be referred to the Baryonychidae. <i>Angaturama</i> can also be referred to this clade, based on the presence of a rostral rosette and a premaxilla with seven tooth positions (Kellner 1996; Kellner and Campos 1996). Since both specimens come from the same horizon, they might represent the same taxon (in which case the name <i>Irritator challengeri</i> would be the senior synonym), but more material is needed to confirm this (see Kellner 1996). The recently described species <i>Spinosaurus marocannus</i> Russell, 1996, and <i>Cristatusaurus lapparenti</i> Taquet and Russell, 1998, are regarded as <i>nomina dubia.</i>
description: Published as part of <i>Rauhut, Oliver W. M., 2003, The interrelationships and evolution of basal theropod dinosaurs, pp. 1-213 in Special papers in palaeontology 69</i> on pages 34-36, DOI: 10.5281/zenodo.3382576
description: {"references": ["STROMER, E. 1915. Ergebnisse der Forschungsreisen Prof. E. Stromers in den WUsten Agyptens. II. Wirbeltierreste der Baharije-Stufe (unterstes Cenoman). 3. Das Original des Theropoden Spinosaurus aegyptiacus nov. gen., nov. spec. Abhandlungen der Koniglich Bayerischen Akademie der Wissenschaften, Mathematisch-Physikalische Klasse, 28, 1 - 32.", "WILSON, J. a. and sereno, p. c. 1998. Early evolution and higher-level phylogeny of sauropod dinosaurs. Society of Vertebrate Paleontology, Memoir, 5, 1 - 68.", "BUFFETAUT, E. 1989. New remains of the enigmatic dinosaur Spinosaurus from the Cretaceous of Morocco and the affinities between Spinosaurus and Baryonyx. Neues Jahrbuch fur Geologie und Palaontologie, Monatshefte, 1989, 79 - 87.", "------ 1992. Remarks on the Cretaceous theropod dinosaurs Spinosaurus and Baryonyx. Neues Jahrbuch fur Geologie und Palaontologie, Monatshefte, 1992, 88 - 96.", "TAQUET, P. 1976. Geologie et paleontologie du gisement de Gadoufaoua (Aptien du Niger). Cahiers de Paleontologie du CNRS, 1 - 191.", "KELLNER, a. w. a. 1996. Remarks on Brazilian dinosaurs. Memoirs of the Queensland Museum, 39, 611 - 626."]}