Things that go bump in the night: evolutionary interactions between cephalopods and cetaceans in the tertiary
Article first published online: 23 JUL 2007
Volume 40, Issue 4, pages 335–343, December 2007
How to Cite
LINDBERG, D. R. and PYENSON, N. D. (2007), Things that go bump in the night: evolutionary interactions between cephalopods and cetaceans in the tertiary. Lethaia, 40: 335–343. doi: 10.1111/j.1502-3931.2007.00032.x
- Issue published online: 23 JUL 2007
- Article first published online: 23 JUL 2007
- Manuscript received on 21/01/2006; manuscript accepted on 15/05/2007.
Echolocation has evolved independently in several vertebrate groups, and hypotheses about the origin of echolocation in these groups often invoke abiotic mechanisms driving morphological evolution. In bats, for example, the ecological setting associated with the origin of echolocation has been linked to global warming during the Palaeocene–Eocene; similarly, the origin of toothed whales (odontocetes) has been broadly correlated with the establishment of the circum-Antarctic current. These scenarios, and the adaptational hypotheses for the evolution of echolocation with which they are associated, neglect a consideration of possible biotic mechanisms. Here we propose that the origin of echolocation in odontocetes was initially an adaptation for nocturnal epipelagic feeding – primarily on diel migrating cephalopods. We test this hypothesis using data on the temporal, geographical, and water column distributions of odontocetes and cephalopods, and other global events from their respective tertiary histories. From this analysis, we suggest that echolocation in early odontocetes aided nocturnal feeding on cephalopods and other prey items, and that this early system was exapted for deep diving and hunting at depths below the photic zone where abundant cephalopod resources were available 24 h a day. This scenario extends to the evolution of other cephalopod feeding (teuthophagous) marine vertebrates such as pinnipeds and Mesozoic marine reptiles.