Exceptional bone density DXA values of the rostrum of a deep-diving marine mammal: a new technical insight in the adaptation of bone to aquatic life

Zotti, Alessandro; Poggi, Roberto; Cozzi, Bruno

doi:10.1007/s00256-009-0647-4

Cited by 11 publications

(8 citation statements)

References 17 publications

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“…Elongation of the facial skull, coalescence of the cervical spine, and absence of pelvic limbs, are well known key features of the whale and dolphin structure. Imaging evidenced peculiar features of cetacean bones, including absence of a medullary cavity in the humerus, radius and ulna substituted by an hour-glass shaped trabecular architecture [8], [9]; modification of the mandible to increase sound-receiving properties [10]; presence of atypical gradients of density of the rostrum in deep-divers [11], [12]. These morphological features are considerably different from the equivalent of terrestrial mammals, and constitute a peculiar acquisition of the order.…”

Section: Introductionmentioning

confidence: 99%

Fetal and Early Post-Natal Mineralization of the Tympanic Bulla in Fin Whales May Reveal a Hitherto Undiscovered Evolutionary Trait

et al. 2012

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The evolution of the cetacean skeleton followed a path that differentiated this group from other terrestrial mammals about 50 million years ago [1], and debate is still going on about the relationships between Cetacea and Artiodactyla [2], [3], [4]. Some skeletal traits of the basilosaurids (the more advanced forms of Archaeocetes), such as the expansion of the peribullary air sinuses, dental modification and vertebral size uniformity [5] are maintained and further emphasized also in contemporary odontocetes and mysticetes. Using Dual-Energy X-Ray Absorptiometry here we report that the deposition of bone mineral in fetal and newborn specimens of the fin whale Balaenoptera physalus is remarkably higher in the bulla tympanica than in the adjacent basal skull or in the rest of the skeleton. Ossification of the tympanic bulla in fetal Artiodactyla (bovine, hippopotamus) is minimal, becomes sensible after birth and then progresses during growth, contrarily to the precocious mineralization that we observed in fin whales. Given the importance of the ear bones for the precise identification of phylogenetic relationship in therian evolution [6], this feature may indicate a specific evolutionary trait of fin whales and possibly other cetacean species or families. Early mineralization of the tympanic bulla allows immediate sound conduction in the aquatic medium and consequently holds potential importance for mother-calf relationship and postnatal survival.

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Section: Introductionmentioning

confidence: 99%

Fetal and Early Post-Natal Mineralization of the Tympanic Bulla in Fin Whales May Reveal a Hitherto Undiscovered Evolutionary Trait

et al. 2012

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“…The changes embrace also the structure of the (formerly) long bones of the arm and forearm, whose medullary cavity has been lost and replaced by a complex cancellous trabecular texture (Felts and Spurrel, , ), able to resist the torsion forces applied by the resistance of water. A highly specialized skeletal adaptation, the high density of the rostrum in deep‐diving Ziphiidae, was discovered relatively early in modern cetacean research (Forbes, ), and later on quantified by bone‐density analyses (Currey, 1969; Zioupos et al, ; Zylberberg et al, ; de Buffrenil et al, ; Zotti et al, ; Cozzi et al, ). The latter techniques, based on density analyses, recently led to characterize the early mineralization of the tympanic bulla in fin whales, a potentially significant specific evolutionary trait (Cozzi et al, ).…”

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confidence: 99%

Precocious Ossification of the Tympanoperiotic Bone in Fetal and Newborn Dolphins: An Evolutionary Adaptation to the Aquatic Environment?

Cozzi

Podestà

Vaccaro

et al. 2015

The Anatomical Record

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The present study, performed with a dual-energy X-ray (DXA) bone densitometer on a series of fetal and newborn striped and short-beaked common dolphins, shows that the bone density of the area of the tympanic bulla within the tympanoperiotic complex starts with 0.483 g cm 22 in 5-to 6-month-old specimens of striped (or common) dolphin fetuses and reaches 1.841 g cm 22 in newborn striped dolphins, with values consistently higher than in other parts of the skull or elsewhere in the skeleton. The same results apply to the common bottlenose dolphins, in which the area of the tympanic bulla has a density of 0.312 g cm 22 in 5-month-old specimens and becomes four times as much in newborns. Regardless of the areal bone density results correlated to the DXA-technique, comparisons with DXAbone density data in the literature referred to other mammals emphasize the presence of very high mineral deposition in the area of the tympanoperiotic bone in fetal and newborn dolphins and the most dense part of it belongs to the tympanic bulla. The early osseous maturation of the tympanic bulla area may be compared to what described in fin whales and may represent an unique ontogenetic and phylogenetic feature of cetaceans, possibly related to the development of essential acoustic sense and establishment of immediate post-natal mother-calf relationship.

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“…Till now, the only studies addressing cetaceans in which this technique has been used concerned the flippers of S. coeruleoalba (Guglielmini et al, 2002) and of T. truncatus (Butti et al, 2007), and the rostrum of M. densirostris (Zotti et al, 2009). To the best of our knowledge, this is the first systematic application of DXA to the comparative study of BMD of the rostrum of toothed whales.…”

Section: Discussionmentioning

confidence: 99%

“…It is unclear whether bone formation arises from ossification of the cartilage (McCann, 1965;MacLeod, 2002), or derives from a dorsal growth and intrusion of the vomer (Fraser, 1942;Heyning, 1989). In beaked whales, this ossification may produce in some species a very dense and compact bone (Raven, 1942;Heyning, 1989;de Buffrènil and Casinos, 1995;de Buffrènil et al, 2000;Zotti et al, 2009). This unique feature is one of the anatomical characteristics that clearly distinguish the skull of beaked whales from that of the family Delphinidae, including an elevated wide vertex and reduced dentition.…”

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confidence: 99%

Bone Density Distribution Patterns in the Rostrum of Delphinids and Beaked Whales: Evidence of Family‐Specific Evolutive Traits

Cozzi

Panin

Butti

et al. 2010

The Anatomical Record

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Toothed whales have undergone a profound telescopic rearrangement of the skull, with elongation of facial bones and formation of a hollow rostrum, filled in vivo by the mesorostral cartilage. In most species of the family Ziphiidae, this latter cartilage becomes secondarily ossified, producing in some cases the densest bone existing in nature. Starting from this observation, we wanted to investigate the patterns of distribution of bone mineral density (BMD) in the rostrum of two families of toothed whales with different ecological and behavioral traits: Delphinidae and Ziphiidae. We analyzed BMD non invasively by means of the dual energy X-ray absorptiometry technology, and found two different density distribution patterns that distinctly set the two families apart. Namely, BMD values decrease from the proximal to the distal region of the rostrum in delphinids, whereas the beaked whales show a BMD peak in the central region. Possible functions such as ballast or protection against clashes might be likely, although more data about the species of both families is needed to give better evidence. Anat Rec, 293:235-242, 2010. V V C 2009 Wiley-Liss, Inc.

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Exceptional bone density DXA values of the rostrum of a deep-diving marine mammal: a new technical insight in the adaptation of bone to aquatic life

Cited by 11 publications

References 17 publications

Fetal and Early Post-Natal Mineralization of the Tympanic Bulla in Fin Whales May Reveal a Hitherto Undiscovered Evolutionary Trait

Fetal and Early Post-Natal Mineralization of the Tympanic Bulla in Fin Whales May Reveal a Hitherto Undiscovered Evolutionary Trait

Precocious Ossification of the Tympanoperiotic Bone in Fetal and Newborn Dolphins: An Evolutionary Adaptation to the Aquatic Environment?

Bone Density Distribution Patterns in the Rostrum of Delphinids and Beaked Whales: Evidence of Family‐Specific Evolutive Traits

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