Internal vascularity of the dermal plates of Stegosaurus (Ornithischia, Thyreophora)

Farlow, James O.; Hayashi, Sachio; Tattersall, Glenn J.

doi:10.1007/s00015-010-0021-5

Cited by 57 publications

(85 citation statements)

References 60 publications

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“…These theories include the use of dorsal plates for display (Carpenter 1998;Main et al 2005;Hayashi et al 2009), thermoregulation (Farlow et al 1976Buffrénil et al 1986;Farlow et al 2010) and defence (Marsh 1877;Gilmore 1914;Bakker 1986, Mallison 2010. The fact that the plates had a keratinous covering has implications on all these hypotheses, and must therefore be considered when evaluating these suggestions.…”

Section: The Function Of the Dorsal Plates In Stegosauriansmentioning

confidence: 99%

“…Moreover, keratinous covering in reptiles and birds, like the beaks of birds, are often coloured and interpreted as being used for display (e.g., Tattersall et al 2009). Thermoregulation A thermoregulatory function for the plates has been discussed extensively (e.g., Farlow et al 1976;Buffrénil et al 1986;Main et al 2005;Hayashi et al 2009;Farlow et al 2010), with recent studies accepting a possible exaptation of the plates for this use, although they do not consider it the main function (Main et al 2005;Hayashi et al 2009;Farlow et al 2010). As noted by Farlow et al (1976), a thermoregulatory use would not be optimized through the existence of a keratinous covering.…”

Section: Displaymentioning

confidence: 99%

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Exceptional stegosaur integument impressions from the Upper Jurassic Morrison Formation of Wyoming

Christiansen

Tschopp

2010

Swiss J Geosci

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Dinosaur skin impressions are rare in the Upper Jurassic Morrison Formation, but different sites on the Howe Ranch in Wyoming (USA), comprising specimens from diplodocid, camarasaurid, allosaurid and stegosaurian dinosaurs, have proven to be a treasure-trove for these softtissue remains. Here we describe stegosaurian skin impressions from North America for the first time, as well as the first case of preservation of an impression of the integument that covered the dorsal plates of stegosaurian dinosaurs in life. Both have been found closely associated with bones of a specimen of the stegosaurian Hesperosaurus mjosi CARPENTER, MILES and CLOWARD 2001. The scales of the skin impression of H. mjosi are very similar in shape and arrangement to those of Gigantspinosaurus sichuanensis OUYANG 1992, the only other stegosaurian dinosaur from which skin impressions have been described. Both taxa show a ground pattern of small polygonal scales, which in some places is interrupted by larger oval tubercles surrounded by the small scales, resulting in rosette-like structures. The respective phylogenetic positions of G. sichuanensis as a basal stegosaurian and H. mjosi as a derived form suggest that most stegosaurians had very similar skin structures, which also match the most common textures known in dinosaurs. The integumentary impression from the dorsal plate brings new data to the long-lasting debate concerning the function of dorsal plates in stegosaurian dinosaurs. Unlike usual dinosaur skin impressions, the integument covering the dorsal plates does not show any scale-like texture. It is smooth with long and parallel, shallow grooves, a structure that is interpreted as representing a keratinous covering of the plates. The presence of such a keratinous covering has affects on all the existing theories concerning the function of stegosaurian plates, including defense, thermoregulation, and display, but does not permit to rule out any of them.

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Section: The Function Of the Dorsal Plates In Stegosauriansmentioning

confidence: 99%

Section: Displaymentioning

confidence: 99%

Exceptional stegosaur integument impressions from the Upper Jurassic Morrison Formation of Wyoming

Christiansen

Tschopp

2010

Swiss J Geosci

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“…Until recently, most attention for histological patterns in the Thyreophora has been paid to their osteoderms, focusing on the armor of ankylosaurs [16], [20], [58] and on stegosaur plates and spikes [15], [17], [19]–[21], [58]. The first insights in their long bone histology were provided by the studies of Padian et al [23], describing long bone histology of Scutellosaurus , and by the detailed work on stegosaur long and girdle bone histology by Hayashi et al [19] and Redelstorff and Sander [24].…”

Section: Discussionmentioning

confidence: 99%

Long Bone Histology and Growth Patterns in Ankylosaurs: Implications for Life History and Evolution

2013

Self Cite

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The ankylosaurs are one of the major dinosaur groups and are characterized by unique body armor. Previous studies on other dinosaur taxa have revealed growth patterns, life history and evolutionary mechanisms based on their long bone histology. However, to date nothing is known about long bone histology in the Ankylosauria. This study is the first description of ankylosaurian long bone histology based on several limb elements, which were sampled from different individuals from the Ankylosauridae and Nodosauridae. The histology is compared to that of other dinosaur groups, including other Thyreophora and Sauropodomorpha. Ankylosaur long bone histology is characterized by a fibrolamellar bone architecture. The bone matrix type in ankylosaurs is closest to that of Stegosaurus. A distinctive mixture of woven and parallel-fibered bone together with overall poor vascularization indicates slow growth rates compared to other dinosaurian taxa. Another peculiar characteristic of ankylosaur bone histology is the extensive remodeling in derived North American taxa. In contrast to other taxa, ankylosaurs substitute large amounts of their primary tissue early in ontogeny. This anomaly may be linked to the late ossification of the ankylosaurian body armor. Metabolically driven remodeling processes must have liberated calcium to ossify the protective osteodermal structures in juveniles to subadult stages, which led to further remodeling due to increased mechanical loading. Abundant structural fibers observed in the primary bone and even in remodeled bone may have improved the mechanical properties of the Haversian bone.

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“…However, it is well known that animals such as crocodilians are able to increase and decrease the flow of blood between the core and surface of the body to affect heating and cooling rates [14], and birds are able to increase breathing rates to effect elimination of excess body heat (“panting”) [38]. There is also the ability of lizards to change their skin color from light to dark to improve their ability to absorb the warmth of the sun, with the converse being that a lighter colored skin will absorb less infrared radiation and slow the rate of heating.…”

Section: Discussionmentioning

confidence: 99%

“…The dorsal ‘sails’ of late Palaeozoic synapsids such as those of Dimetrodon and Edaphosaurus have been argued to have functioned as radiators [9]–[12]. Stegosaurian dinosaurs, with their prominent, plate-like osteoderms mounted high on their backs, have also inspired speculations about their ability to lose heat via the extensive vascularization of the plates [13], [14]. However, in the case of the synapsids, it has been shown that the sails were more likely to have been for sexual display based on scaling arguments, and that dorsal sails in small species of Dimetrodon would have been ineffective as radiators [15].…”

Section: Introductionmentioning

confidence: 99%

Sauropod Necks: Are They Really for Heat Loss?

Henderson

2013

PLoS ONE

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Three-dimensional digital models of 16 different sauropods were used to examine the scaling relationship between metabolism and surface areas of the whole body, the neck, and the tail in an attempt to see if the necks could have functioned as radiators for the elimination of excess body heat. The sauropod taxa sample ranged in body mass from a 639 kg juvenile Camarasaurus to a 25 t adult Brachiosaurus. Metabolism was assumed to be directly proportional to body mass raised to the ¾ power, and estimates of body mass accounted for the presence of lungs and systems of air sacs in the trunk and neck. Surface areas were determined by decomposing the model surfaces into triangles and their areas being computed by vector methods. It was found that total body surface area was almost isometric with body mass, and that it showed negative allometry when plotted against metabolic rate. In contrast, neck area showed positive allometry when plotted against metabolic rate. Tail area show negative allometry with respect to metabolic rate. The many uncertainties about the biology of sauropods, and the variety of environmental conditions that different species experienced during the groups 150 million years of existence, make it difficult to be absolutely certain about the function of the neck as a radiator. However, the functional combination of the allometric increase of neck area, the systems of air sacs in the neck and trunk, the active control of blood flow between the core and surface of the body, changing skin color, and strategic orientation of the neck with respect to wind, make it plausible that the neck could have functioned as a radiator to avoid over-heating.

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Internal vascularity of the dermal plates of Stegosaurus (Ornithischia, Thyreophora)

Cited by 57 publications

References 60 publications

Exceptional stegosaur integument impressions from the Upper Jurassic Morrison Formation of Wyoming

Exceptional stegosaur integument impressions from the Upper Jurassic Morrison Formation of Wyoming

Long Bone Histology and Growth Patterns in Ankylosaurs: Implications for Life History and Evolution

Sauropod Necks: Are They Really for Heat Loss?

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