Ontogenetic shape changes in Pomacentridae (Teleostei, Perciformes) and their relationships with feeding strategies: a geometric morphometric approach

The present study explores the shape changes of cranial structures directly involved in food capturing during growth after reef settlement in two species of Pomacentridae (Dascyllus aruanus and Pomacentrus pavo). Landmark-based geometric morphometrics were used to study allometric patterns and related shape changes in four skeletal units: neurocranium, suspensorium and opercle, mandible and premaxilla. At settlement, the larvae of both species have a relatively similar morphology, especially with respect to the mandible. Their shapes suggest a feeding mode defined as ram/suction-feeding. Ontogenetic shape changes show a shift to a suction feeding mode of prey capture. The main transformations involved are an increase in height of the suspensorium and the opercle, an elevation of the supraoccipital crest, a relative shortening of the mandible, and a lengthening of the ascending process of the premaxilla. Shape changes of the mandible in the two studied species also reflect an increase of biting capacities. The high disparity between adult shape results from differences in the rate and in the length of ontogenetic trajectories, from divergence of the ontogenetic trajectories (neurocranium, mandible, and premaxilla) and parallel shifts of the trajectories in the size-shape space (suspensorium and opercle). In an evolutionary context, allometric heterochronies during ontogeny of different skeletal unit of the head may be considered as a basis for the explanation of the diversity of damselfishes

Rock magnetic experiments conducted on a representative sample (P2-9), corresponding to Zijdervelt diagrams of the Figure 3A and B.

<p>A) Progressive isothermal remanent magnetization (IRM) acquisition curve. B) Back-field curve. C) Hysteresis loop (±1 T). D) Thermomagnetic curve; arrows indicate heating and cooling cycles. E) Heating cycle of the Figure 4 D was amplified.</p

Primary data from Iberian archaeological sites dating in the Early-Middle Pleistocene Transition time span (942 to 641 kyr).

a<p>MQ, Iberian biozones. ^bLCT: large cutting technology; PBC: pebble and core technology <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0103634#pone.0103634-Shea1" target="_blank">[14]</a>.</p

Barranc de la Boella large cutting tools (LCT).

<p>a) split cobble of schist showing trihedral pick configuration from level 2 at Pit 1 Locality (P1L) site; b) schist cleaver from level 2 at EF site.</p