Condition in which bones have an abnormally elevated density
Skull dome of Stegoceras (AMNH 5450) showing cross-section thickness
Pachyostosis[1] is a non-pathological condition in vertebrate animals in which the bones experience a thickening, generally caused by extra layers of lamellar bone. It often occurs together with bone densification (osteosclerosis), reducing inner cavities. This joint occurrence is called pachyosteosclerosis. However, especially in the older literature, "pachyostosis" is often used loosely, referring to all osseous specializations characterized by an increase in bone compactness and/or volume.[2] It occurs in both terrestrial and, especially, aquatic or semi-aquatic vertebrates.[2]
In aquatic animals, such as seacows (manatees and dugongs), Thalassocnus,[3] and plesiosaurs, pachyostosis in the thoracic region provides (or provided) ballast against the air-filled lungs. This maintains neutral buoyancy in aquatic habitats.
Most giant deer showed pronounced pachyostosis of the mandible and skull.[4][5] It has been suggested that this served to store minerals for antler growth.[6] Many Pachycephalosauria and most members of the Dinocephalia clade of therapsids had thickened skull bones, probably used in head-butting contests.[7]
^Domning, D. P.; Debuffrenil, V. (1991). "Hydrostasis in the Sirenia - Quantitative Data and Functional Interpretations". Marine Mammal Science. 7 (4): 331–368. Bibcode:1991MMamS...7..331D. doi:10.1111/j.1748-7692.1991.tb00111.x.
^ abHoussaye, A (2009). ""Pachyostosis" in aquatic amniotes: a review". Integrative Zoology. 4 (4): 325–340. doi:10.1111/j.1749-4877.2009.00146.x. PMID 21392306.
^Amson, E.; de Muizon, C.; Laurin, M.; Argot, C.; de Buffrenil, V. (2014). "Gradual adaptation of bone structure to aquatic lifestyle in extinct sloths from Peru". Proceedings of the Royal Society B: Biological Sciences. 281 (1782): 1–6. doi:10.1098/rspb.2014.0192. PMC 3973278. PMID 24621950.
^van der Made, J.; Tong, H. W. (2008). "Phylogeny of the giant deer with palmate brow tines Megaloceros from west and Sinomegaceros from east Eurasia" (PDF). Quaternary International. 179 (1): 135–162. Bibcode:2008QuInt.179..135V. doi:10.1016/j.quaint.2007.08.017.
^Vislobokova, I. A. (2013). "Morphology, taxonomy, and phylogeny of megacerines (Megacerini, Cervidae, Artiodactyla)". Paleontological Journal. 47 (8): 833–950. Bibcode:2013PalJ...47..833V. doi:10.1134/s0031030113080017. S2CID 86697746.
^Lister, A. M. (1994). "The evolution of the giant deer, Megaloceros giganteus (Blumenbach)". Zoological Journal of the Linnean Society. 112 (1–2): 65–100. doi:10.1111/j.1096-3642.1994.tb00312.x.
^Snively, E.; Cox, A. (2008). "Structural Mechanics of Pachycephalosaur Crania Permitted Head-Butting Behavior". Palaeontologia Electronica. 11: 17.
Pachyostosis is a non-pathological condition in vertebrate animals in which the bones experience a thickening, generally caused by extra layers of lamellar...
together with bone thickening (pachyostosis). This joint occurrence is called pachyosteosclerosis. Axial osteomalacia Pachyostosis Pachyosteosclerosis Heinrich...
be inconsistent if caused by some disease or other condition. Due to pachyostosis, the vertebrae are greatly inflated, making them nearly twice as voluminous...
notorious pachyostosis (bone thickening) during development, which ultimately modified the skull roof of adults. Consequently, pachyostosis was responsible...
jaws. The bones of the postcranial skeleton are thick, having undergone pachyostosis. Mesosaurus is unusual among reptiles in that it possesses a cleithrum...
the disadvantage of hampering coming up again. Young plesiosaurs show pachyostosis, an extreme density of the bone tissue, which might have increased relative...
holotype (AMNH 5550) and seven topotypes (AMNH 5551-5557). The degree of pachyostosis varies within the skulls of the specimens, and Broom believed this to...
Pachyosteosclerosis is a combination of thickening (pachyostosis) and densification (osteosclerosis) of bones. It makes bones more heavy, but also more...
thickening (pachyostosis) somewhat similar to that in Megaloceros, unlike Megaloceros, the vomer is largely unaffected. The pachyostosis is among the...
1111/1749-4877.12080. PMID 24148672. Morales, J.; Pickford, M.; Soria, D.; Pachyostosis (1993). "Lorancameryx pachyostoticus Nov. Gen. Nov. Sp. and Its Bearing...
160th. The ribs from the 45-48th and 105-108th vertebrae show signs of pachyostosis, bony thickening and growth. Along with its sister genus Pachyrhachis...
Jean-Claude; Bardet, Nathalie (12 September 2008). "An analysis of vertebral 'pachyostosis' in Carentonosaurus mineaui (Mosasauroidea, Squamata) from the Cenomanian...
surface when the jaws were shut. Most dinocephalians also developed pachyostosis of the bones in the skull, which seems to have been an adaptation for...
side of their lower jaw. Like other sirenians, the dugong experiences pachyostosis, a condition in which the ribs and other long bones are unusually solid...
water, which would be confirmed by their lack of gastroliths and of pachyostosis or dense bone. The tail would have served to keep the body in a descending...
layer groups in a tusk indicates the age of a dugong. Sirenians exhibit pachyostosis, a condition in which the ribs and other long bones are solid and contain...
than a coastal marine environment. Recently described embryos show that pachyostosis of the ribs (which were thicker and denser than in terrestrial tetrapods)...
flattened, boxy cross-section and its gastralia (belly ribs) exhibit pachyostosis (thickening). The total length of Tatenectes has been estimated at 2–3...
information is drawn from this segment, though all do display characteristic pachyostosis and osteosclerosis. Thickening proximal rib sections and notable emphasis...
Sinomegaceros, like those of Megaloceros giganteus, are robust and display pachyostosis with the robustness being the most extreme in S. pachyosteus. S. yabei...
It can be distinguished by other rubidgeines by its lack of cranial pachyostosis and rugosoties, and by its relatively small orbits. The classification...
skull and mandible of the Irish elk exhibit substantial thickening (pachyostosis), with the early and complete obliteration of cranial sutures. Based...
lost their flight abilities by the end of the Early Cretaceous, minimal pachyostosis in Brodavis suggests the possibility of some volant abilities. Longrich...
lost their flight abilities by the end of the Early Cretaceous, minimal pachyostosis in Brodavis suggests the possibility of some volant abilities. †Canadaga...
mass which can be caused by osteosclerosis (inner compaction of bone), pachyostosis (hyperplasy of compact cortices) or pachyeosclerosis (combination of...
pachyostic ribs and gastralia described as ‘sausage-like’ in profile. Pachyostosis is known from a number of Pliosaurid genera (for example Monquirasaurus)...
aquatic mammals, the ribs did not exhibit osteosclerosis. They did exhibit pachyostosis, and were made thicker and heavier with additional layers of lamellar...
Pyrohiv south of Kyiv. Although Gritsenko took note of the advanced pachyostosis of the material, likening it to what is seen in modern sirenians, he...
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