Only isolated teeth are known (have been identified) from this genus, and those are limited to North America.

Pseudohypolophus mcnultyi:

  • Thurmond (1971: 220-222) provided a diagnosis for Hypolophus? mcnultyi (using Albian material from Texas) as:
        "Hexagonal or rhombic teeth with biparted root; no central cavity. Root slightly smaller than crown, not offset in hexagonal teeth but offset in rhombic specimens. Crown almost entirely of orthodentine, with osteodentine in root only; no pulp cavity".    
    In discussing these teeth, he went on to note:
    - Late Aptian-Late Cenomanian and that these specimens "are identical to those described by McNulty (1964)" from the Late Cenomanian of Texas.
    - rhombic teeth smaller than hexagonal or distorted (most common) hexagonal teeth and have proportionally taller roots that are offset anteriorly.
    Assuming Thurmond included teeth from a single species, the most important aspect of the description relates to dentition-design: hexagonal medial teeth, followed by 'distorted-hexagonal', and finally rhombic (offset) lateral-most positions.
    Most misleading could be the statement that these were "identical" to McNulty's (1964) Cenomanian specimens — were they and the dentition-design identical?
  • Meyer (1974: 156-57, unpublished) included an expanded design-envelope as Parahypolophus mcnultii noting its orthodentine crown rather than osteodentine (as present in the extant Hypolophus). Meyer included Albian-Campanian specimens (TX & MS); his figure 48 specimens appear to include examples of Protoplatyrhina (fig. 48a,b) and P. ellipsis (fig. 48c,d).
  • Cappetta & Case 1975b erected Pseudohypolophus and designated mcnultyi as type species,
  • Cappetta (1987: 142) included the genus in Rhinobatoidei (and maintained that position in his 2006 paper).
  • Welton & Farish (1993: 134, figs. 1-4) included P. mcnultyi in Texas as Aptian-Cenomanian only. Their imaged specimens were Albian in age and showed better detail than Thurmond's sketches, particularly the salient margino-lingual foramina — the examples include both the rhombic and ?"distorted hexagonal" teeth as included by Thurmond.
  • Cappetta & Case (1999:42; pls. 28.1-9, 29.1-4 ) reported P. mcnultyi from the Late Cenomanian of Texas. Their figured specimens are less angular than the Albian examples; lack the salient marginolateral foramina; elongate crowns are in more-lateral positions; and no rhombic laterals were depicted. The overall tooth and dentition-designs appear closer to P. ellipsis (below), rather than P. mcnultyi.

    Other reports of "Pseudohypolophus mcnultyi" include:

  • Lauginiger (1986: 56) - Campanian of New Jersey,
  • Schwimmer (1986:115) - Campanian of Georgia,
  • Robb (1989: 89; as Rhombodus levis) - Campanian of North Carolina,
  • Williamson et al (1989: 244; as cf Pseudohypolophus, fig. 4d-e only) - Sant., NM
  • Manning & Dockery (1992) - Santonian-Campanian of Mississippi,
  • Welton & Farish (1993: 134) - Common in Aptian-Cenomanian of Texas
  • Williamson et al. (1993) - Cenomanian-Turonian of Arizona,
  • Hoganson et al. (1996) - Maastrichtian of North Dakota.
  • Hartstein et al (1999: 18) - Maastrichtian of Maryland,
  • Welton & Farish (1993: 134) - Aptian-Cenomanian of Texas.
  • Johnson & Lucas (2002) - Coniacian–Santonian of New Mexico
  • Beker et al (2004: 786) - Maastrichtian of South Dakota,
  • Beker et al (2010: 259, figs. 6.8-11) - Turonian of Utah.
  • Spielmann et al (2011: 387, figs. 2a,b) included H. cf mcnultyi from the Cenomanian of NM.
  • Hamm & Cicimurri (2011:120) included as Pseudohypolophus sp a small (3mm) tooth from the Atco Formation (Early Coniacian) of Texas.
    Case & Cappetta (1997) did not include this genus in the Maastrichtian of Texas.

    Pseudohypolophus ellipsis:

  • Case et al (2001:92, pl 2, fig 37-42) erected Pseudohypolophus ellipsis for "mcnultyi"-like teeth from the Santonian of Georgia. They deemed the relevant differences to be the size (to 1 cm) and that "P. mcnultyi is rhomboid in its shape (oral view) whereas P. ellipsis nov. sp. is elliptical in its shape (oral view)".
    It is true that the reported size of their specimen far exceeds older examples and the P. mcnultyi type material tends to have an angular (4 or 6-sided) shape; but, tooth wear, ontogenetic variations and a gradual evolutionary trend could explain these differences. Subsequent reports from North America reverted to P. mcnultyi.
  • In reporting on the Santonian of New Mexico, Bourdon et al (2011:43) noted that not only were the crowns not angular, but pavement design (based on crown offset relative the nutritive groove) was contrary to Thurmond's description. They went on to note that a study of the P. ellipsis type specimen (Santonian, GA) found it to be actually 5 mm in width (not 10 as described). In this paper they reported these teeth as "Pseudohypolophus" ellipsis.
  • At this time elasmo.com will use "Pseudohypolophus" ellipsis for Atlantic and Gulf Coast teeth (Santonian-Campanian) that correspond with the Bourdon et al (2011) New Mexico reference images (figs. 25d-e, 26a-n). Lacking a good sample of Pseudohypolophus mcnultyi (ss Thurmond, 1971) teeth, that author's description will be adhered to, rather than the broader design-envelope of Meyer (1974) or the interpretation of Cappetta & Case (1999). Considering the similarity in tooth-design amongst Protoplatyrhina, the smooth-crowned Myledaphus and Pseudohypolophus, it wouldn't be surprising if one or more additional species were present during the Late Cretaceous of NA.

     

     

    Selected References

    Becker, M.A., Chamberlain, J.A., jr., and Terry, D.O., 2004. Chondrichthyans from the Fairpoint Member of the Fox Hills Formation (Maastrichtian), Meade County, South Dakota. Journal of Vertebrate Paleontology, 24:780–793.
    Becker, M.A., Wellner, R.W., Mallery, C.S., jr. and Chamberlain, J.A., jr., 2010. Chondrichthyans from the lower Ferron Sandstone Member of the Mancos Shale (Upper Cretaceous: Middle Turonian) of Emery and Carbon Counties, Utah, USA; Journal of Paleontology, 84(2): 248–266.
    Bourdon, J., Wright, K., Lucas, S.G., Spielmann, J.A. and Pence, R., 2011. Selachians from the Upper Cretaceous (Santonian) Hosta Tongue of the Point Lookout Sandstone, central New Mexico. New Mex. Mus. Nat. His. and Sc., Bulletin 52; 54pp.
    Cappetta, H., 1987. Chondrichthyes II. Mesozoic and Cenozoic Elasmobranchii. In: Handbook of Paleoichthyologie, vol. 3b, Gustav Fischer Verleg, Stuttgart, 193 pp.
    Cappetta, H., 2006.. Elasmobranchii post-Triadici (index generum et specierum). In: Riegraf, W. (Ed) Fossilium Catalogus I:Animalia 142. Leiden, Backhuys Publish, 472pp.
    Cappetta, H. and Case, G., 1975b. Sélaciens nouveaux du Crétecé du Texas. Géobios, 8, (40: 303-307.
    Case, G. and Cappetta, H.. 1997. A new selachian fauna from the late Maastrichtian of Texas. Münchener Geowissenschaften Abhandungen 34:131-189.
    Case, G, D. Schwimmer, P. Borodin and J. Leggett, 2001. A new selachian fauna from the Eutaw Formation (Upper Cretaceous/Early to Middlew Santonian) of Chattahoochee County, Georgia. Palaeontographica Abt. A, 261:83-102.
    Hamm, S.A. and D.J. Cicimurri, 2011. Early Coniacian (Late Cretaceous) selachian fauna from the basal Atco Formation, Lower Austin Group, north central Texas; Paludicola [Rochester Institute of Vertebrate Paleontology] 8(3):107-127.
    Hartstein, E., Decina, L. and Keil, R., 1999. A Late Cretaceous (Severn Formation) Vertebrate Assemblage from Bowie, Maryland. The Mosasaur, VI:17-23.
    Hoganson, J., Erickson, M. and Holland, F., 1996. Vertebrate paleontology of the Timber Lake Member, Fox Hills Formation (Maastrichtian) North Dakota. Journal of Vertebrate Paleontology 16(3,supplement):41A
    Johnson, S.C. and Lucas, S.G., 2002b. Histological study of the ray Pseudohypolophus mcnultyi (Thurmond) from the Late Cretaceous (Coniacian–Santonian) of central New Mexico. New Mexico Geology, 24:88–90.
    Lauginiger, E., 1986.An Upper Cretaceous vertebrate assemblage from Big Brook, New Jersey. The Mosasaur, III:53-62.
    Manning, E., 2006. Late Campanian vertebrate fauna of the Frankstown site, Prentiss County, Mississippi; systematics, paleoecology, taphonomy, sequence stratigraphy. Unpub. PhD dissertation, Tulane Univ., New Orleans, xvii+419 p., 16 pls.
    Manning, E, and Dockery III, D, 1992. A guide to the Frankstown vertebrate fossil locality (Upper Cretaceous), Prentiss County, Mississippi. Mississippi Dept. of Env. Qual., Office of Geology, Circular 4, 43 p., 12 pls.
    Meyer, R., 1974. Late Cretaceous elasmobranchs from the Mississippi and East Texas embayments of the Gulf Coastal Plain. Unpubl. PhD dissertation, Southern Methodist Univ., Dallas, xiv+419 p.
    Robb, A., 1989. The Upper Cretaceous (Campanian, Black Creek Formation) Fossil Fish Fauna of Phoebus Landing, Bladen County, North Carolina, The Mosasaur, Vol 4, pp 75-92.
    Schwimmer, D., 1986. Late Cretaceous fossils from the Blufftown Formation (Campanian) in western Georgia. The Mosasaur, III:109-119.
    Spielmann, J.A., R. Pence, K.W.Wright and S.G. Lucas, 2011. A selachian-dominated assemblage from the Upper Cretaceous (Cenomanian) Clay Mesa Member, Mancos Formation, Santa Fe County, NM, in: Sullivan et al., eds., 2011, Fossil Record 3. New Mexico Museum of Natural History and Science, Bulletin 53.
    Thurmond, J., 1971. Cartilaginous fishes of the Trinity Group and related rocks (Lower Cretaceous) of North Central Texas. Southeast. Geol., 13, (4), pp 207-227.
    Welton, B. and Farish, R., 1993. The Collector's Guide to Fossil Sharks and Rays from the Cretaceous of Texas. Before Time, Texas. 204 pp.
    Williamson, T., J. Kirkland and S. Lucas, 1993. Selachians from the Greenhorn cyclothem ("Middle" Cretaceous: Cenomanian-Turonian), Black Mesa, Arizona, and the paleogeographic distribution of Late Cretaceous selachians. Journal of Paleontology 67(3), pp 447-474.

     

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