We used iodine‐enhanced and traditional CT scanning to visualize the internal anatomy of five fetuses of humpback whale representing the first two‐thirds of gestation, and we combine these data with previously published reports to provide the first comprehensive qualitative description of the sequence of developmental changes that characterize the skull and dentition. This trait can be used to stage balaenopterid specimens only as extensive throat grooves are absent in other extant mysticetes (Fig.In the lower jaw, 36 and 38 tooth germs are visible in the left and right sides, respectively.

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Squares = humpback specimens included in this study and retro‐fitted to the growth curve; crosses = lengths at which important steps in the teeth to baleen transition were recorded in the species (not necessarily observed in specimens); diamonds = estimates of length at birth (m).

The alveolar groove appears shallower in the lower jaw as well.Balaenopterids are strikingly diverse in size as adults, a condition also reflected in newborns, which range from 2.5 m in length for the minke whale to 8 m for the blue whale (Laws.The humpback whale specimens described here are labeled on the graph (Fig.By comparing the growth curves among species, it appears that the rorquals have faster fetal growth than odontocetes, with a marked increase in growth rate in the last one third of gestation. The morphological features of the skull are summarized as follows: the supra-orbital process of the frontal is elongated laterally and its posterior margin is straight; the orbit is relatively short considering the skull size; the squamosal is slender and protrudes anterolaterally at an obtuse angle; the squamosal sulcus is not developed at the base of the zygomatic process; the dorsal shape of the supra-occipital is equilaterally triangular; the basioccipital and the basisphenoid are fused, forming a wide plane on the ventral surface; the alisphenoid is not exposed in the temporal region. Bowhead whale skull (Balaena mysticetus) at the abandoned Kekerten Island whaling station, Nunavut, Canada, North America. Read our.Etsy uses cookies and similar technologies to give you a better experience, enabling things like:Detailed information can be found in Etsy’s.Some of the technologies we use are necessary for critical functions like security and site integrity, account authentication, security and privacy preferences, internal site usage and maintenance data, and to make the site work correctly for browsing and transactions.Cookies and similar technologies are used to improve your experience, to do things like:Without these technologies, things like personalized recommendations, your account preferences, or localisation may not work correctly. The only living species is,A new specimen of the humpback whale was discovered in Chiba Prefecture, central Japan. (,Regarding the development of dentition in dolphins, Armfield et al.

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Embryo/fetus line is based on the age estimate for balaenopterids listed by Roston et al. Share your thoughts, experiences and the tales behind the art. Lists of the Japanese fossil cetaceans have been reported (.We would like to thank the students of the Earth Science Club of Kogane Senior High School for their help with excavations and preparations of the fossil. © 2018 American Association for Anatomy.Cetaceans (baleen whales or Mysticeti and toothed whales or Odontoceti) evolved from terrestrial ancestors related to modern artiodactyl taxa such as hippos and cows (Gatesy et al..Heterodont dentition was a key feature in early mammals, which allowed them to diversify and occupy a variety of ecological niches (Hunter and Jernvall.Considerable information about how the transition from the ancestral mammalian dentition and raptorial feeding to baleen‐aided filter feeding occurred in evolutionary time is available thanks to an extensive fossil record of mysticetes (e.g., Deméré and Berta,The goal of this article is provision of a different perspective on the teeth‐to‐baleen transition debate by investigating changes in the internal skull anatomy during the prenatal development of one species of Balaenopteridae, the humpback whale (,In the context of better understanding the relationship between ontogeny and evolution in mysticetes, we identify three major objectives. The description of a blue whale specimen of comparable age by Ridewood (.In addition to elucidating cranial ossification patterns in mysticetes, another focus of our investigation of development of the humpback whale is the teeth‐to‐baleen transition.

Moreover, the Procrustes superimposition performed in MorphoJ (Klingenberg.After a rapid growth at the end of the embryonic period, the braincase increases in size at a constant rate, while the rostrum progressively elongates (Figs.By considering the evolution of skull shape in stem mysticetes (Fig.In postnatal development, the rostrum, frontal and squamosal bones are known to grow proportionally larger relative to the rest of the skull at least in an another Balaenopteridae species, the minke whale (,In order to place various ontogenetic events associated with the teeth‐to‐baleen transition in a broader context we constructed growth curves that also enable comparison of mysticete growth patterns with those of close relatives, namely odontocetes, and terrestrial artiodactyls.

The number of germs in the lower jaw is always fewer than in the upper jaw. However, it is only a general assessment of whether the specimens are in the first, mid or last portion of gestation, given the assumptions used to produce the growth curves as well as possible inaccuracies of the original data.The only data available on tooth resorption in the humpback whale come from Eschricht (,Outside of Balaenopteridae, the only description of the teeth‐to‐baleen transition during ontogeny was provided by Thewissen et al. Humpback Whale Skull 3D Model Highly detailed 3d model of humpback whale skull.