Project 933: R. A. Racicot, T. D. Demere, B. L. Beatty, R. W. Boessenecker. 2014. Unique feeding morphology in a new prognathous extinct porpoise from the Pliocene of California. Current Biology. 24 (7):774-779.
Specimen: † Semirostrum ceruttii (SDSNH:65276)
View: dorsal

Abstract

Modern porpoises (Odontoceti: Phocoenidae) are some of the smallest cetaceans and usually feed near the seafloor on small fish and cephalopods [1, 2 and 3]. Within both extinct and extant phocoenids, no evidence for specialized mandibular morphology has been documented [4, 5, 6 and 7]. Here we describe a new species of extinct porpoise, Semirostrum ceruttii, from the marine Pliocene San Diego (4.2–1.6 mega-annum, Ma) and Purisima (5–2.5 Ma) formations of California. The mandibles comprise a long, fused, and nearly edentulous prognathous symphysis, extending farther beyond the rostrum than in any known mammal. Phylogenetic analyses based on morphology reconstruct Semirostrum ceruttii as sister to extant (crown) porpoise species with moderate support. We describe the spectacularly preserved holotype specimen based on computed tomography (CT) scans, which allowed visualization of the elongate mental and accessory canals within the symphysis. The elongate canals are similar to those found in Rynchops birds [ 8] and were likely involved in sensory function. Oblique labial wear facets present on numerous small conical mandibular teeth posterior to the symphysis suggest regular contact with benthic substrate. The unique mandibular and dental characteristics, along with robust scapulae, sternum, and unfused cervical vertebrae, support the interpretation that this species employed a form of benthic skim feeding by using its mandible to probe for and obtain prey.


Read the article »

Article DOI: http://dx.doi.org/10.1016/j.cub.2014.02.031

Project DOI: 10.7934/P933, http://dx.doi.org/10.7934/P933
This project contains
  • 5 Media
  • 3 Documents
  • 1 Taxon
  • 1 Specimen
Total size of project's media files: 10 MB

Download Project SDD File
Currently Viewing:
MorphoBank Project 933

    This research
    supported by



    Members

    member name taxa specimens media
    Rachel Racicot
    Project Administrator
    Last logged in 10/06/14
    115


    Project has no matrices defined.



    Project views

    type number of views Individual items viewed (where applicable)
    Total project views15317
    Project overview2844
    Media views5519Media search (3438 views); M326049 (1 view); M326050 (1 view); M330203 (421 views); M340680 (418 views); M340679 (405 views); M340681 (432 views); M340677 (403 views);
    Documents list1669
    Taxon list1384
    Specimen list1670
    Views for media list1580
    Bibliography651




    Project downloads

    type number of downloads Individual items downloaded (where applicable)
    Total downloads from project193
    Document downloads7Character list (3 downloads); Murakami Matrix with Semirostrum ceruttii (4 downloads);
    Media downloads3M340681 (2 downloads); M330203 (1 download);
    Project downloads183