Development of the Skull of the Pantropical Spotted Dolphin (<i>Stenella attenuata</i>)

Moran, Meghan M.; Nummela, Sirpa; Thewissen, J. G. M.

doi:10.1002/ar.21388

Cited by 28 publications

(52 citation statements)

References 34 publications

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“…Thus, in typical mammals, the ossification phase is mostly completed in the fetal phase as the nose continues to grow (Rehorek et al, 2011(Rehorek et al, , 2015. The condition in S. attenuata deviates from this scheme, insofar that the duct originates in the upper eyelid (this study) at about the same time as the lacrimal bone begins to develop (Moran et al, 2011). Thus, the NLD develops later than expected (heterochronic shift) and too late to be covered by the lacrimal bone (thus no lacrimal foramen is formed).…”

Section: Timingmentioning

confidence: 99%

Ontogeny of the Orbital Glands and Their Environs in the Pantropical Spotted Dolphin (Stenella attenuata: Delphinidae)

Rehorek

Hillenius

Lovano

et al. 2017

The Anatomical Record

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The nasolacrimal duct (NLD) connects the orbital (often associated with the Deep Anterior Orbital gland: DAOG, a.k.a. Harderian gland) and nasal regions in many tetrapods. Adult cetaceans are usually said to lack an NLD, and there is little agreement in the literature concerning the identity of their orbital glands, which may reflect conflicting definitions rather than taxonomic variation. In this study, we examined an embryological series of the pantropical spotted dolphin (Stenella attenuata), and report numerous divergences from other tetrapods. Underdeveloped eyelids and a few ventral orbital glands are present by late Stage (S) 17. By S 19, circumorbital conjunctival glands are present. In S 20, these conjunctival glands have proliferated, eyelids (and scattered palpebral glands) have formed, and a duct similar to the NLD has appeared. Subsequently, both the palpebral glands and the NLD are progressively reduced by S 22, even as the conjunctival glands exhibit regional growth. In most tetrapods examined, the ontogeny of the NLD follows a series of three stages: Inception of NLD, Connection of orbit and nasal cavity by the NLD and Ossification (i.e., formation of the bony canal surrounding the NLD, emerging into the orbit via the lacrimal foramen in the lacrimal bone). In contrast, the dolphin NLD originates at the same time as the lacrimal bone, and a lacrimal foramen fails to develop. The cetacean fossil record shows that a lacrimal foramen was present in the earliest ancestral amphibious, freshwater forms, but was soon lost as the lineage invaded the oceans. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 301:77-87, 2018. © 2017 Wiley Periodicals, Inc.

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Section: Timingmentioning

confidence: 99%

Ontogeny of the Orbital Glands and Their Environs in the Pantropical Spotted Dolphin (Stenella attenuata: Delphinidae)

Rehorek

Hillenius

Lovano

et al. 2017

The Anatomical Record

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“…Thewissen et al (), Thewissen and Heyning (), and Moran et al () presented a developmental series of several embryos and one fetus of Stenella attenuata based on the Carnegie Stage System (e.g., Butler and Juurlink, ). In addition, there have been several other embryonic studies on odontocetes, for example, the studies by Pilleri and Gihr (, b) on river dolphins ( Platanista gangetica , Pontoporia blainvillei ).…”

Section: Introductionmentioning

confidence: 99%

“…Thus, most of our current knowledge of prenatal specimens derives from material collected from pregnant females and was taken abroad from whaling ships, whaling stations at land or from stranded animals. Thewissen et al (2003), Thewissen and Heyning (2007), and Moran et al (2011) presented a developmental series of several embryos and one fetus of Stenella attenuata based on the Carnegie Stage System (e.g., Butler and Juurlink, 1987). In addition, there have been several other embryonic studies on odontocetes, for example, the studies by Pilleri and Gihr (1976a, b) on river dolphins (Platanista gangetica, Pontoporia blainvillei).…”

Section: Introductionmentioning

confidence: 99%

Prenatal cranial ossification of the humpback whale (Megaptera novaeangliae)

Hampe

Franke

Hipsley

et al. 2015

Journal of Morphology

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Being descendants of small terrestrial ungulate mammals, whales underwent enormous transformations during their evolutionary history, that is, extensive changes in anatomy, physiology, and behavior were evolved during secondary adaptations to life in water. However, still only little is known about whale ontogenetic development, which help to identify the timing and sequence of critical evolutionary events, such as modification of the cetacean ear. This is particularly true for baleen whales (Mysticeti), the group including the humpback whale Megaptera novaeangliae. We use high-resolution X-ray computed tomography to reinvestigate humpback whale fetuses from the Kükenthal collection at the Museum für Naturkunde, Berlin, thus, extending historic descriptions of their skeletogenesis and providing for the first time sequences of cranial ossification for this species. Principally, the ossification sequence of prenatal Megaptera follows a typical mammalian pattern with the anterior dermal bones being the first ossifying elements in the skull, starting with the dentary. In contrast to other mammals, the ectotympanic bone ossifies at an early stage. Alveolar structure can be observed in both the maxillae and dentaries in these early prenatal specimens but evidence for teeth is lacking. Although the possibility of obtaining new embryological material is unlikely due to conservation issues, our study shows that reexamination of existing specimens employing new technologies still holds promise for filling gaps in our knowledge of whale evolution and ontogeny.

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“…The ontogenesis of the cetacean skeleton has been studied in dolphin species [13], and only partially in larger baleen whales [14]. We had access to a few fetal and newborn specimens of fin whale Balaenoptera physalus (Linnaeus, 1758) in which the ossification of the skull was incomplete and individual bones could be separated.…”

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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Development of the Skull of the Pantropical Spotted Dolphin (Stenella attenuata)

Cited by 28 publications

References 34 publications

Ontogeny of the Orbital Glands and Their Environs in the Pantropical Spotted Dolphin (Stenella attenuata: Delphinidae)

Ontogeny of the Orbital Glands and Their Environs in the Pantropical Spotted Dolphin (Stenella attenuata: Delphinidae)

Prenatal cranial ossification of the humpback whale (Megaptera novaeangliae)

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

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