Contrasting with the suction feeding of modern relatives in the families Kogiidae and Physeteridae, Miocene physeteroids display a broad range of feeding strategies. Despite the continuous improvements of the fossil record, the transition from the earliest sperm whales to suction feeding forms as well as the once prominent macroraptorial forms remains poorly understood. Here, we investigate a partial skull from Lower Miocene (Burdigalian) strata of the Chilcatay Formation of the East Pisco Basin (southern Peru). This specimen is recognised as belonging to an undescribed species of Diaphorocetus, a genus previously known only by the holotype of Diaphorocetus poucheti, from a roughly coeval unit in Patagonia (Argentina). Differing from the latter in its smaller cranial dimensions, higher tooth count, and minor differences in the position of facial foramina, the Peruvian fossil confirms the presence of a key character of D. poucheti, the marked dorsoventral flattening of the maxillary portion of the rostrum. Such cranial proportions suggest that, compared to other physeteroids, Diaphorocetus spp. were more efficient at performing fast lateral sweeps of their rostra to capture small- to medium-sized prey items with their proportionally small teeth. Recovered as stem physeteroids in our phylogenetic analysis, these forms contribute to the ecomorphological disparity of the Early Miocene sperm whales, but without displaying any of the cranial and dental changes occurring in later, macroraptorial and suction-feeding sperm whales. The discovery of a member of Diaphorocetus in southern Peru increases the similarities between the toothed whale faunas from the local Chilcatay Formation and the Gaiman and Monte Leon formations of Argentinian Patagonia, pointing not only to dispersal routes between the southeastern Pacific and southwestern Atlantic during the Burdigalian, but also to overall similar ecological settings along the coasts of Peru and Patagonia at that time.
A FLAT-SNOUTED SPERM WHALE FROM THE LOWER MIOCENE OF THE SOUTHEASTERN PACIFIC (EAST PISCO BASIN, PERU) SUPPORTS AFFINITIES WITH THE SOUTHWESTERN ATLANTIC CETACEAN FAUNA
Olivier LAMBERTPrimo
;Alberto COLLARETA
Secondo
;Marco MERELLA;Giovanni BIANUCCIUltimo
2023-01-01
Abstract
Contrasting with the suction feeding of modern relatives in the families Kogiidae and Physeteridae, Miocene physeteroids display a broad range of feeding strategies. Despite the continuous improvements of the fossil record, the transition from the earliest sperm whales to suction feeding forms as well as the once prominent macroraptorial forms remains poorly understood. Here, we investigate a partial skull from Lower Miocene (Burdigalian) strata of the Chilcatay Formation of the East Pisco Basin (southern Peru). This specimen is recognised as belonging to an undescribed species of Diaphorocetus, a genus previously known only by the holotype of Diaphorocetus poucheti, from a roughly coeval unit in Patagonia (Argentina). Differing from the latter in its smaller cranial dimensions, higher tooth count, and minor differences in the position of facial foramina, the Peruvian fossil confirms the presence of a key character of D. poucheti, the marked dorsoventral flattening of the maxillary portion of the rostrum. Such cranial proportions suggest that, compared to other physeteroids, Diaphorocetus spp. were more efficient at performing fast lateral sweeps of their rostra to capture small- to medium-sized prey items with their proportionally small teeth. Recovered as stem physeteroids in our phylogenetic analysis, these forms contribute to the ecomorphological disparity of the Early Miocene sperm whales, but without displaying any of the cranial and dental changes occurring in later, macroraptorial and suction-feeding sperm whales. The discovery of a member of Diaphorocetus in southern Peru increases the similarities between the toothed whale faunas from the local Chilcatay Formation and the Gaiman and Monte Leon formations of Argentinian Patagonia, pointing not only to dispersal routes between the southeastern Pacific and southwestern Atlantic during the Burdigalian, but also to overall similar ecological settings along the coasts of Peru and Patagonia at that time.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
