Abstract
Modern beaked whales (Ziphiidae) are among the least known groups of mammals. This
family of toothed whales forage at great depths on cephalopods, their favored prey. The
origin and timing of their specialisation to deep diving is almost unknown. The discovery
of a new fossil beaked whale from Denmark may unveil the origin of deep diving in the
family.
This project had two mains objectives. First, describing a new fossil specimen from
the Miocene of Denmark. Second, investigating deep diving abilities in extinct beaked
whales.
The fossil specimen represent a new genus and species of Ziphiidae, called Dagonodum
mojnum. A cladistic analysis placed it in a basal group of the ziphiids. D. mojnum
provided new information about feeding strategies and sexual dimorphism in basal ziphiids.
Basal ziphiids were proposed to be predators feeding in shallow waters. This hypothesis
was supported by the morphology of basal ziphiids. Besides, geological context in
which basal ziphiids are discovered also support it. Finally, a unique discovery confirmed
it, the association predator-prey between a basal ziphiid and a presumed expelled stomach
content of several fish living in shallow waters.
Further investigation of the skeleton of basal ziphiids was performed. Muscle reconstructions
indicated the neck of basal ziphiids to allow lateral and dorsoventral movements.
This result contrasted with the rigid neck of modern ziphiids. By contrast, morphology
of the forelimb did not differ between basal and modern ziphiids. As a result,
changes in the shape of the flipper in ziphiids occurred before their specialization to deep
diving.
Finally, Stable isotopic analyses were tested as an independent proxy for deep diving.
Combined oxygen and carbon isotopes revealed sufficient to assess deep diving abilities.
family of toothed whales forage at great depths on cephalopods, their favored prey. The
origin and timing of their specialisation to deep diving is almost unknown. The discovery
of a new fossil beaked whale from Denmark may unveil the origin of deep diving in the
family.
This project had two mains objectives. First, describing a new fossil specimen from
the Miocene of Denmark. Second, investigating deep diving abilities in extinct beaked
whales.
The fossil specimen represent a new genus and species of Ziphiidae, called Dagonodum
mojnum. A cladistic analysis placed it in a basal group of the ziphiids. D. mojnum
provided new information about feeding strategies and sexual dimorphism in basal ziphiids.
Basal ziphiids were proposed to be predators feeding in shallow waters. This hypothesis
was supported by the morphology of basal ziphiids. Besides, geological context in
which basal ziphiids are discovered also support it. Finally, a unique discovery confirmed
it, the association predator-prey between a basal ziphiid and a presumed expelled stomach
content of several fish living in shallow waters.
Further investigation of the skeleton of basal ziphiids was performed. Muscle reconstructions
indicated the neck of basal ziphiids to allow lateral and dorsoventral movements.
This result contrasted with the rigid neck of modern ziphiids. By contrast, morphology
of the forelimb did not differ between basal and modern ziphiids. As a result,
changes in the shape of the flipper in ziphiids occurred before their specialization to deep
diving.
Finally, Stable isotopic analyses were tested as an independent proxy for deep diving.
Combined oxygen and carbon isotopes revealed sufficient to assess deep diving abilities.
| Original language | English |
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| Publisher | Natural History Museum of Denmark, Faculty of Science, University of Copenhagen |
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| Publication status | Published - 2016 |