Variations and anomalies in the vertebral column of the bottlenose dolphin (Tursiops truncatus) from southern Brazil

Costa, Ana P. B.; Loch, Carolina; Simões-Lopes, Paulo César

doi:10.5597/lajam00230

Cited by 8 publications

(11 citation statements)

References 15 publications

(19 reference statements)

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“…In cetaceans, the vertebral column is the primary scaffold to which muscles that generate the swimming movement attach. [ 3 ] These dorsoventral undulations of their tail flukes are powered by the large epaxial and hypaxial muscles which primarily attach to the spinous processes of the vertebral column. Dolphins demonstrate a method of travel called “porpoising,” long parabolic ballistic jumping alternating with periods of gliding during which no swimming occurs and an acceleration phase characterized by high thrust swimming.…”

Section: Discussionmentioning

confidence: 99%

“…In reality, vertebral anatomy does tend to vary with anomalies seen in over 50% of individual dolphins, representing developmental anomalies or adaptations to variable environments. [ 3 ] However, attention has been paid to gross features and their likely adaptive significance in comparison to that of humans. A more detailed morphological analysis and modeling of swimming movements will further elucidate the complex swimming mechanisms in this remarkable species.…”

Section: Discussionmentioning

confidence: 99%

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A morphological analysis of the cervical spine of the dolphin

Goel

Shah²,

Gaikwad

2021

J Craniovert Jun Spine

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Objective: Morphology of bones of cervical vertebrae of dolphin was studied. When compared to human vertebrae the structural modifications in terms of functional needs are evaluated. Material: Morphological analysis of duly prepared bones of species D. delphis was carried out. Result: The craniocervical junction and cervical spine of the dolphin ( Delphinus delphis ) has unique adaptations to allow for dorsoventrally undulating swimming movements as well as leaping out of water. The key differences from the human cervical spine include the absence of an odontoid process limiting rotatory movements, disproportionately short and wide vertebral bodies and a unilaterally elongated transverse process of the axis. Moreover, the cervical spine of the dolphin is disproportionally short compared to humans. These modifications give strength and stability to the cervical spine allowing maximal agility for flexion-extension movements of the lumbocaudal spine, which are keys for propulsion. The unilaterally elongated transverse process likely allows for rotatory spinning, suggesting possible lateral dominance of rotatory spin in this species. Conclusions: Despite the skeletal adaptations, the cervical spine is strongly resonant of a mammalian heritage with a remarkably similar form and structure to house neurovascular contents and to allow muscular attachments.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A morphological analysis of the cervical spine of the dolphin

Goel

Shah²,

Gaikwad

2021

J Craniovert Jun Spine

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“…The occurrence of morphological, traumatic, and pathological changes has been reported for cetaceans of different age group and sex. Changes are related to environmental, behavioral, or anthropic factors (Costa et al, 2016; Denuncio et al, 2016; Félix et al, 2007; Fettuccia et al, 2013; Kompanje, 1999; Montes et al, 2004; Niño‐Torres et al, 2019; San Martin et al, 2016; Sweeny et al, 2005; Tomo et al, 2018; Van Bressem et al, 2006, 2007).…”

Section: Figurementioning

confidence: 99%

Skull and mandible alterations in Amazon river dolphins (de Blainville, 1817) (Cetacea, Iniidae, Inia spp.)

Lara,

da Silva,

Amaral

2023

Marine Mammal Science

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Osteological studies help to understand biological issues such as locomotion, distribution, evolution, and ecology of a given species (Bell et al., 2002;Cooper et al., 2007). Such studies are widely used in taxonomy, making it possible to show phylogenetic relationships (Perrin, 1975;Tanaka & Fordyce, 2014). Macroscopic analysis of bones may provide relevant data on the life history of vertebrates (Bianucci et al., 2010;Simões-Lopes et al., 2008).The number of studies on bone changes in cetaceans has increased in recent decades. The occurrence of morphological, traumatic, and pathological changes has been reported for cetaceans of different age group and sex.

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“…Although a variety of vertebral column malformations have been documented in cetaceans (Alstrup et al, 2013;Beatty and Rothschild, 2008;Berghan and Visser, 2000;Bertulli et al, 2015;Costa et al, 2016;Hellier et al, 2011;Félix et al, 2007;Kompanje, 1999 and the references therein), reports of osteological trauma akin to shear-compression fractures are exceedingly rare (Watson et al, 2004;Godfrey and Altman, 2005; and possibly Thomas et al, 2008, fig. 2B LACM 151218).…”

Section: Introductionmentioning

confidence: 99%

A Miocene cetacean vertebra showing a partially healed longitudinal shear-compression fracture, possibly the result of domoic acid toxicity or failed predation

Godfrey¹,

Beatty²

2022

Palaeontol Electron

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CT-scans of a cetacean pathological vertebra from the Calvert Formation of the Miocene Chesapeake Group of Maryland, show features characteristic of a shear-compression fracture with comminution and significant periosteal reaction. The etiology of the injury suggests an intense hyperflexion of vertebrae in at least the lumbar region of the axial column. The trauma was sufficiently forceful to break much of the lower twofifths of the centrum away from the anterior end of the body of the vertebra. However, the trauma was not immediately fatal as significant fusion of fragmented elements was well underway at the time of death. Much of the lateral and ventral surfaces of the centrum are covered with a thick layer of periosteal reactive bone. This reactive periosteal bone growth could be due to spondyloarthritis, infection, or from the traumatic event itself, if the direct muscle attachments on the vertebra were avulsed.A single megatoothed shark tooth from Otodus megalodon was found with the vertebra. It is not known if the tooth came to be there serendipitously, or if it was associated because it was lost as a result of the possible originating failed predation event, or during a final successful predation or subsequent scavenging event.The fractures are severe and unlikely to have had an endogenous origin like convulsions, seizures, or spasms. Seizures can cause vertebral fractures in humans, including elderly adults with poor bone health as well as physically fit younger individuals. Seizures causing injuries of this magnitude have not been observed in cetaceans, though domoic acid toxicity from harmful algal blooms are known to cause seizures in cetaceans, and are implicated in the deaths of neonatal skim-feeding mysticetes. It is unlikely, but possible, that a large mysticete would be affected by domoic acid toxicity to the point of a spinal fracture-causing seizure. Similarly, protozoal infections are known to cause seizures in cetaceans, though physical diagnosis of this is impossible in a fossil. Partly healed bone fractures of the face from possible collisions with the seafloor have been reported from fossil mysticetes of shallower regions of this fauna, but a spinal fracture this far back in the spinal column seems unlikely to be the result of a seafloor collision. Even though the cause of the vertebral hyperflexion and resulting trauma is unknown, a plausible cause was a crushing ambush delivered by a macro-predatory shark or macroraptorial physeteroid. In spite of extant cetaceans being subjected to anthropogenically-induced trauma, which include vessel-strike blunt force injuries of many different kinds, shear-compression fractures and periosteal reactions like the ones detailed here have not yet been reported in extant cetaceans. Therefore, we consider the fracture as likely due to an impact from a predator, such as Otodus megalodon, or possibly from seizures due to a harmful algal bloom and resulting domoic acid toxicity. In either scenario, the cetacean survived.

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Variations and anomalies in the vertebral column of the bottlenose dolphin (Tursiops truncatus) from southern Brazil

Abstract: This paper describes cases of morphological variation and bone anomalies in the axial skeleton of the bottlenose dolphin, with emphasis on the vertebral column and considering the physical maturity of those specimens.

Cited by 8 publications

References 15 publications

A morphological analysis of the cervical spine of the dolphin

A morphological analysis of the cervical spine of the dolphin

Skull and mandible alterations in Amazon river dolphins (de Blainville, 1817) (Cetacea, Iniidae, Inia spp.)

A Miocene cetacean vertebra showing a partially healed longitudinal shear-compression fracture, possibly the result of domoic acid toxicity or failed predation

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