Limits...
Evolutionary Patterns among Living and Fossil Kogiid Sperm Whales: Evidence from the Neogene of Central America.

Velez-Juarbe J, Wood AR, De Gracia C, Hendy AJ - PLoS ONE (2015)

Bottom Line: However, this organ is much reduced in kogiids and may have become functionally different.Furthermore our results show that reduction of the spermaceti organ has occurred iteratively in kogiids, once in Thalassocetus antwerpiensis in the early-middle Miocene, and more recently in Kogia spp.Finally, comparison of Nanokogia with the coeval Scaphokogia cochlearis from Peru shows that these two species display a greater morphological disparity between them than that observed between the extant members of the group.

View Article: PubMed Central - PubMed

Affiliation: Department of Mammalogy, Natural History Museum of Los Angeles County, Los Angeles, California, United States of America; John D. Cooper Archaeological and Paleontological Center, Department of Geological Sciences, California State University, Fullerton, California, United States of America.

ABSTRACT
Kogiids are known by two living species, the pygmy and dwarf sperm whale (Kogia breviceps and K. sima). Both are relatively rare, and as their names suggest, they are closely related to the sperm whale, all being characterized by the presence of a spermaceti organ. However, this organ is much reduced in kogiids and may have become functionally different. Here we describe a fossil kogiid from the late Miocene of Panama and we explore the evolutionary history of the group with special attention to this evolutionary reduction. The fossil consists of cranial material from the late Tortonian (~7.5 Ma) Piña facies of the Chagres Formation in Panama. Detailed comparison with other fossil and extant kogiids and the results of a phylogenetic analysis place the Panamanian kogiid, herein named Nanokogia isthmia gen. et sp. nov., as a taxon most closely related to Praekogia cedrosensis from the Messinian (~6 Ma) of Baja California and to Kogia spp. Furthermore our results show that reduction of the spermaceti organ has occurred iteratively in kogiids, once in Thalassocetus antwerpiensis in the early-middle Miocene, and more recently in Kogia spp. Additionally, we estimate the divergence between extant species of Kogia at around the late Pliocene, later than previously predicted by molecular estimates. Finally, comparison of Nanokogia with the coeval Scaphokogia cochlearis from Peru shows that these two species display a greater morphological disparity between them than that observed between the extant members of the group. We hypothesize that this reflects differences in feeding ecologies of the two species, with Nanokogia being more similar to extant Kogia. Nanokogia shows that kogiids have been part of the Neotropical marine mammal communities at least since the late Miocene, and gives us insight into the evolutionary history and origins of one of the rarest groups of living whales.

Show MeSH

Related in: MedlinePlus

Ventral views of kogiid skulls.Aprixokogia kelloggi (USNM 187015), 12A, Scaphokogia cochlearis (MNHN PPI 229), 12B, Praekogia cedrosensis (UCMP 315229), 12C, Nanokogia isthmia gen. et sp. nov. (UF 273554), 12D, and (UF 280000), 12E, Kogia sima (LACM 47142), 12F, and K. breviceps (LACM 95745), 12G. Each bone is color-coded for ease of comparison. Areas in white are reconstructed, light gray areas are covered with sediment; diagonal lines denote broken surfaces. Illustrations based on direct observations of the specimens listed.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4414568&req=5

pone.0123909.g012: Ventral views of kogiid skulls.Aprixokogia kelloggi (USNM 187015), 12A, Scaphokogia cochlearis (MNHN PPI 229), 12B, Praekogia cedrosensis (UCMP 315229), 12C, Nanokogia isthmia gen. et sp. nov. (UF 273554), 12D, and (UF 280000), 12E, Kogia sima (LACM 47142), 12F, and K. breviceps (LACM 95745), 12G. Each bone is color-coded for ease of comparison. Areas in white are reconstructed, light gray areas are covered with sediment; diagonal lines denote broken surfaces. Illustrations based on direct observations of the specimens listed.

Mentions: The palatal surface of the maxilla is flat to gently convex. There are no maxillary teeth and only faint indications of a vestigial upper alveolar groove (Figs 3 and 12E; c. 6[1]). The ventrolateral edges are flange-like (maxillary flange of Mead and Fordyce [19]) with their ventral surfaces transversely concave anteromedial to the antorbital notches. The anteriormost extension of the pterygoid sinus is represented by a shallow, oval concave fossa located anteromedial to the ventral infraorbital foramen (Figs 3 and 6), similar to the condition observed in Kogia spp. [30]. The infraorbital foramen is located far anteromedial to the frontal groove (Figs 3–5), being at the level of the middle of the supraorbital process of the frontal; the foramen seems to be bounded dorsally and medially by the maxilla, laterally and ventrally by the lacrimal, and posteriorly by the frontal (Figs 3, 4C, 4D and 5).


Evolutionary Patterns among Living and Fossil Kogiid Sperm Whales: Evidence from the Neogene of Central America.

Velez-Juarbe J, Wood AR, De Gracia C, Hendy AJ - PLoS ONE (2015)

Ventral views of kogiid skulls.Aprixokogia kelloggi (USNM 187015), 12A, Scaphokogia cochlearis (MNHN PPI 229), 12B, Praekogia cedrosensis (UCMP 315229), 12C, Nanokogia isthmia gen. et sp. nov. (UF 273554), 12D, and (UF 280000), 12E, Kogia sima (LACM 47142), 12F, and K. breviceps (LACM 95745), 12G. Each bone is color-coded for ease of comparison. Areas in white are reconstructed, light gray areas are covered with sediment; diagonal lines denote broken surfaces. Illustrations based on direct observations of the specimens listed.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4414568&req=5

pone.0123909.g012: Ventral views of kogiid skulls.Aprixokogia kelloggi (USNM 187015), 12A, Scaphokogia cochlearis (MNHN PPI 229), 12B, Praekogia cedrosensis (UCMP 315229), 12C, Nanokogia isthmia gen. et sp. nov. (UF 273554), 12D, and (UF 280000), 12E, Kogia sima (LACM 47142), 12F, and K. breviceps (LACM 95745), 12G. Each bone is color-coded for ease of comparison. Areas in white are reconstructed, light gray areas are covered with sediment; diagonal lines denote broken surfaces. Illustrations based on direct observations of the specimens listed.
Mentions: The palatal surface of the maxilla is flat to gently convex. There are no maxillary teeth and only faint indications of a vestigial upper alveolar groove (Figs 3 and 12E; c. 6[1]). The ventrolateral edges are flange-like (maxillary flange of Mead and Fordyce [19]) with their ventral surfaces transversely concave anteromedial to the antorbital notches. The anteriormost extension of the pterygoid sinus is represented by a shallow, oval concave fossa located anteromedial to the ventral infraorbital foramen (Figs 3 and 6), similar to the condition observed in Kogia spp. [30]. The infraorbital foramen is located far anteromedial to the frontal groove (Figs 3–5), being at the level of the middle of the supraorbital process of the frontal; the foramen seems to be bounded dorsally and medially by the maxilla, laterally and ventrally by the lacrimal, and posteriorly by the frontal (Figs 3, 4C, 4D and 5).

Bottom Line: However, this organ is much reduced in kogiids and may have become functionally different.Furthermore our results show that reduction of the spermaceti organ has occurred iteratively in kogiids, once in Thalassocetus antwerpiensis in the early-middle Miocene, and more recently in Kogia spp.Finally, comparison of Nanokogia with the coeval Scaphokogia cochlearis from Peru shows that these two species display a greater morphological disparity between them than that observed between the extant members of the group.

View Article: PubMed Central - PubMed

Affiliation: Department of Mammalogy, Natural History Museum of Los Angeles County, Los Angeles, California, United States of America; John D. Cooper Archaeological and Paleontological Center, Department of Geological Sciences, California State University, Fullerton, California, United States of America.

ABSTRACT
Kogiids are known by two living species, the pygmy and dwarf sperm whale (Kogia breviceps and K. sima). Both are relatively rare, and as their names suggest, they are closely related to the sperm whale, all being characterized by the presence of a spermaceti organ. However, this organ is much reduced in kogiids and may have become functionally different. Here we describe a fossil kogiid from the late Miocene of Panama and we explore the evolutionary history of the group with special attention to this evolutionary reduction. The fossil consists of cranial material from the late Tortonian (~7.5 Ma) Piña facies of the Chagres Formation in Panama. Detailed comparison with other fossil and extant kogiids and the results of a phylogenetic analysis place the Panamanian kogiid, herein named Nanokogia isthmia gen. et sp. nov., as a taxon most closely related to Praekogia cedrosensis from the Messinian (~6 Ma) of Baja California and to Kogia spp. Furthermore our results show that reduction of the spermaceti organ has occurred iteratively in kogiids, once in Thalassocetus antwerpiensis in the early-middle Miocene, and more recently in Kogia spp. Additionally, we estimate the divergence between extant species of Kogia at around the late Pliocene, later than previously predicted by molecular estimates. Finally, comparison of Nanokogia with the coeval Scaphokogia cochlearis from Peru shows that these two species display a greater morphological disparity between them than that observed between the extant members of the group. We hypothesize that this reflects differences in feeding ecologies of the two species, with Nanokogia being more similar to extant Kogia. Nanokogia shows that kogiids have been part of the Neotropical marine mammal communities at least since the late Miocene, and gives us insight into the evolutionary history and origins of one of the rarest groups of living whales.

Show MeSH
Related in: MedlinePlus