Terranectes, Rahmat & Koretsky & Osborne & Alford, 2017

Rahmat, S. J., Koretsky, I. A., Osborne, J. E. & Alford, A. A., 2017, New Miocene Monachinae From The Western Shore Of The Chesapeake Bay (Maryland, Usa), Vestnik Zoologii (Vestn. Zool.) 51 (3), pp. 221-242 : 224-225

Terranectes gen. n.

urn:lsid:zoobank.org:act:2B7F666A-7524-4755-8215-C165407FAF90

Etymology. Terra (Latin word for “ground, Earth”) and nectes (Greek word for “swimmer”), implying a semi-aquatic animal adapted more for terrestrial movement than aquatic.

Type species. Terranectes magnus , sp. n.

Included species. In the Upper Miocene of the Chesapeake Group two new monachine species are recorded: T. magnus and T. parvus .

Diagnosis. Monachine seals of medium to large size. Posterior border of glenoid fossa of skull forms deep, wide postglenoid groove in tympanic bone; postglenoid foramen located at end of postglenoid groove, not floored by tympanic bone; long axis of tympanic bulla parallel to midline of skull; carotid canal parallel to surface of basioccipital, its posterior aperture opens ventrally, medial side has fully formed margin.

Humeral deltoid crest strongly developed, short, terminates at middle of diaphysis (similar to Piscophoca pacifica and in contrast to Acrophoca longirostris , Pontophoca sarmatica , Callophoca obscura , Pliophoca etrusca ); greater width of deltoid crest located on its proximal part (similar to Pontophoca sarmatica , Pliophoca etrusca ; and opposite to both Pis. pacifica and Acr. longirostris , where entire deltoid crest approximately same width); in lateral view deltoid crest flattened and oval (similar to Pis. pacifica , Pliophoca etrusca ; and opposite from Acr. longirostris , where deltoid crest significantly elongated; opposite to Callophoca obscura , with flattened and square-shape); proximal end of deltoid crest higher than head (similar to Pliophoca etrusca ; opposite to both Pis. pacifica and Acr. longirostris , where they have same height; opposite to Pontophoca sarmatica , with lesser trochanter higher than head and deltoid crest; opposite to Callophoca obscura , with deltoid crest located below lesser tubercle and below or at same level as head).

Femoral greater trochanter extends proximally slightly higher than head (similar to Pontophoca sarmatica ; and opposite to Acr. longirostris , where greater trochanter extends much higher; opposite to Callophoca obscura , with head extending higher than greater trochanter; opposite to Pliophoca etrusca , with head at same level as greater trochanter); greater trochanter proximal part wider than distal (similar to Acr. longirostris , Pontophoca sarmatica , Callophoca obscura ); trochanteric fossa deep, wide, and open distally, reaching the distal border of head (similar to Callophoca obscura ; opposite to Acr. longirostris , Pontophoca sarmatica and Pliophoca etrusca ); intertrochanteric line disappears at middle of diaphysis (opposite to Acr. longirostris , with longer intertrochanteric line; opposite to Callophoca obscura , with very short intertrochanteric line; opposite to Pliophoca etrusca and Pontophoca sarmatica , with undeveloped line); supracondylar fossa shallow, slender, elongated, and located above lateral condyle (similar to Callophoca obscura ; opposite to Acr. longirostris , with deeper and larger supracondylar fossa; opposite to Pontophoca sarmatica and Pliophoca etrusca , with more horizontally-directed supracondylar fossa); condyles unequal in size (similar to Acr. longirostris , Callophoca obscura , Pliophoca etrusca ).

Innominate bone similar to typical monachines, without lateral excavation (same as Pis. pacifica , Acr. longirostris , Callophoca obscura ); wide, flattened iliac crest (opposite to Pis. pacifica , with rounded and short iliac crest and opposite to Acr. longirostris , with rounded iliac crest that is less wider than Terranectes and more wider than Pis. pacifica ; opposite to Callophoca obscura , with rounded, thick and wide iliac crest); thick specifically across acetabulum (similar to Pis. pacifica and opposite to Acr. longirostris ); reduced iliopectineal eminence (opposite to both Pis. pacifica and Acr. longirostris ); and shallow acetabulum (similar to Callophoca obscura ; opposite to Pis. pacifica and Acr. longirostris , which are deeper and more conical).

Tibia and fibula fused proximally ( Muizon and Hendey, 1980).