Biomechanics of Machaeracanthus pectoral fin spines provide evidence for distinctive spine function and lifestyle among early chondrichthyans
Acanthodians are a major group of Paleaozoic jawed vertebrates that constitute a paraphyletic assemblage of stem-chondrichthyans (Brazeau and Friedman, 2015). Representatives of this group are characterized, among other traits, by the presence of bony spines in front of all paired and median fins except the caudal (Denison, 1979), which has given rise to their colloquial name of 'spiny sharks'. The occurrence of pectoral fin spines is recognized as a potential gnathostome synapomorphy (Miller et al., 2003) or symplesiomorphy (Coates, 2003), being also present in other major groups of Paleaozoic jawed vertebrates, including placoderms (Young, 2010), 'non-acanthodian' chondrichthyans (Miller …
Biomechanical insights into the dentition of megatooth sharks (Lamniformes: Otodontidae)
AbstractThe evolution of gigantism in extinct otodontid sharks was paralleled by a series of drastic modifications in their dentition including widening of the crowns, loss of lateral cusplets, and acquisition of serrated cutting edges. These traits have generally been interpreted as key functional features that enabled the transition from piscivory to more energetic diets based on marine mammals, ultimately leading to the evolution of titanic body sizes in the most recent forms (including the emblematic Otodus megalodon). To investigate this hypothesis, we evaluate the biomechanics of the anterior, lateral, and posterior teeth of five otodontid species under different loading conditions by…
Biomechanics of Machaeracanthus pectoral fin spines provide evidence for distinctive spine function and lifestyle among early chondrichthyans
Biomechanics of Machaeracanthus pectoral fin spines provide evidence for distinctive spine function and lifestyle among early chondrichthyans