{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T10:19:40Z","timestamp":1790158780685,"version":"4.1.0"},"reference-count":22,"publisher":"Wiley","issue":"6","license":[{"start":{"date-parts":[[2007,5,21]],"date-time":"2007-05-21T00:00:00Z","timestamp":1179705600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["The Anatomical Record"],"published-print":{"date-parts":[[2007,6]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>Previous analyses have shown that secondarily aquatic tetrapods, including whales, exhibit osteological adaptations to life in water as part of their complex buoyancy control systems. These structural specializations of bone span hyperostosis through osteoporosis. The past 15 years of paleontological effort has provided an unprecedented opportunity to examine the osteological transformation of whales as they make their transition to an obligate aquatic lifestyle over a 10\u2010million\u2010year period. It is hypothesized that whales manifest their osteological specialization in the same manner as extant semiaquatic and fully aquatic mammals. This study presents and analysis of the microstructural features of bone in early and late archaic cetaceans, and in a comparative sample of modern terrestrial, semiaquatic, and aquatic mammals. Bone histology was examined from the ribs of 10 fossilized individuals representing five early cetacean families, including Pakicetidae, Ambulocetidae, Protocetidae, Remintonocetidae, and Basilosauridae. Comparisons were then made with rib histology from nine genera of extant mammals including: <jats:italic>Odocoileus<\/jats:italic> (deer), <jats:italic>Bos<\/jats:italic> (cow), <jats:italic>Equus<\/jats:italic> (horse), <jats:italic>Canis<\/jats:italic> (dog), <jats:italic>Lutra<\/jats:italic> (river otter), <jats:italic>Enhydra<\/jats:italic> (sea otter), <jats:italic>Choeropsis<\/jats:italic> (pygmy hippo), <jats:italic>Trichechus<\/jats:italic> (sea cow), and <jats:italic>Delphinus<\/jats:italic> (dolphin). Results show that the transition from terrestrial, to semiaquatic, to obligate aquatic locomotion in archaeocetes involved a radical shift in bone function achieved by means of profound changes at the microstructural level. A surprising finding was that microstructural change predates gross anatomical shift in archaeocetes associated with swimming. Histological analysis shows that high bone density is an aquatic specialization that provides static buoyancy control (ballast) for animals living in shallow water, while low bone density is associated with dynamic buoyancy control for animals living in deep water. Thus, there was a shift from the typical terrestrial form, to osteopetrosis and pachyosteosclerosis, and then to osteoporosis in the first quarter of cetacean evolutionary history. Anat Rec, 290:638\u2013653, 2007. \u00a9 2007 Wiley\u2010Liss, Inc.<\/jats:p>","DOI":"10.1002\/ar.20533","type":"journal-article","created":{"date-parts":[[2007,5,25]],"date-time":"2007-05-25T12:21:02Z","timestamp":1180095662000},"page":"638-653","source":"Crossref","is-referenced-by-count":119,"title":["Sink or swim? Bone density as a mechanism for buoyancy control in early cetaceans"],"prefix":"10.1002","volume":"290","author":[{"given":"Noel\u2010Marie","family":"Gray","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kimberly","family":"Kainec","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sandra","family":"Madar","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lucas","family":"Tomko","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Scott","family":"Wolfe","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2007,5,21]]},"reference":[{"key":"e_1_2_6_2_1","doi-asserted-by":"publisher","DOI":"10.1007\/978-1-4899-0159-0_7"},{"key":"e_1_2_6_3_1","doi-asserted-by":"publisher","DOI":"10.1002\/ar.20534"},{"key":"e_1_2_6_4_1","doi-asserted-by":"publisher","DOI":"10.1080\/02724634.1990.10011828"},{"key":"e_1_2_6_5_1","doi-asserted-by":"publisher","DOI":"10.1016\/8756-3282(95)00373-8"},{"key":"e_1_2_6_6_1","doi-asserted-by":"publisher","DOI":"10.1093\/icb\/36.6.628"},{"key":"e_1_2_6_7_1","doi-asserted-by":"publisher","DOI":"10.1002\/ar.20546"},{"key":"e_1_2_6_8_1","doi-asserted-by":"publisher","DOI":"10.1007\/978-1-4757-0878-3_7"},{"key":"e_1_2_6_9_1","unstructured":"GingerichPD UhenMD.1996.Ancalecetus simonsi a new dorudontine archaeocete (Mammalia Cetacea) from the early late Eocene of Wadi Hitan Egypt. Contributions from the University of Michigan Museum of Paleontology Vol. 29. 13:359\u2013401."},{"key":"e_1_2_6_10_1","doi-asserted-by":"publisher","DOI":"10.1007\/978-1-4899-0159-0_8"},{"key":"e_1_2_6_11_1","doi-asserted-by":"publisher","DOI":"10.1101\/gad.13.23.3037"},{"key":"e_1_2_6_12_1","doi-asserted-by":"publisher","DOI":"10.1139\/z01-188"},{"key":"e_1_2_6_13_1","doi-asserted-by":"publisher","DOI":"10.1007\/978-1-4899-0159-0_12"},{"key":"e_1_2_6_14_1","doi-asserted-by":"publisher","DOI":"10.1666\/0022-3360(2007)81[176:TPSOEE]2.0.CO;2"},{"key":"e_1_2_6_15_1","first-page":"289","volume-title":"Secondary adaptation of tetrapods to life in water","author":"Ricqles A","year":"2001"},{"key":"e_1_2_6_16_1","doi-asserted-by":"publisher","DOI":"10.1017\/S0094837300019850"},{"key":"e_1_2_6_17_1","doi-asserted-by":"publisher","DOI":"10.1126\/science.263.5144.210"},{"key":"e_1_2_6_18_1","first-page":"1","article-title":"Ambulocetus natans, an Eocene cetacean (Mammalia) from Pakistan","volume":"191","author":"Thewissen JGM","year":"1996","journal-title":"Courier Forsch\u2010Inst Senckenberg"},{"key":"e_1_2_6_19_1","doi-asserted-by":"publisher","DOI":"10.1038\/35095005"},{"key":"e_1_2_6_20_1","doi-asserted-by":"publisher","DOI":"10.1080\/10292380009380550"},{"key":"e_1_2_6_21_1","doi-asserted-by":"publisher","DOI":"10.1007\/978-1-4899-0159-0_2"},{"key":"e_1_2_6_22_1","doi-asserted-by":"publisher","DOI":"10.1002\/ar.20545"},{"key":"e_1_2_6_23_1","doi-asserted-by":"publisher","DOI":"10.1007\/978-1-4899-0159-0_1"}],"container-title":["The Anatomical Record"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/api.wiley.com\/onlinelibrary\/tdm\/v1\/articles\/10.1002%2Far.20533","content-type":"unspecified","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/anatomypubs.onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/ar.20533","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,8]],"date-time":"2025-10-08T14:46:59Z","timestamp":1759934819000},"score":1,"resource":{"primary":{"URL":"https:\/\/anatomypubs.onlinelibrary.wiley.com\/doi\/10.1002\/ar.20533"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2007,5,21]]},"references-count":22,"journal-issue":{"issue":"6","published-print":{"date-parts":[[2007,6]]}},"alternative-id":["10.1002\/ar.20533"],"URL":"https:\/\/doi.org\/10.1002\/ar.20533","archive":["Portico"],"relation":{},"ISSN":["1932-8486","1932-8494"],"issn-type":[{"value":"1932-8486","type":"print"},{"value":"1932-8494","type":"electronic"}],"subject":[],"published":{"date-parts":[[2007,5,21]]}}}