Haresiceras placentiforme, from Cretaceous Atlas of Ancient Life.

Belongs within: Stephanocerataceae.
Contains: Scaphites.

The Scaphitaceae are a group of often heteromorphic ammonites known from the Cretaceous (Upper Albian to Maastrichtian) with an initial spiral opening into a more or less distinct hook. In many derived genera, the hook becomes less distinct and the conch is more or less consistently coiled. Members of the family may be divided between two lineages with microconches of the Otoscaphitinae possessing long lateral lappets that are absent in Scaphitinae. Otoscaphitinae became extinct in the Santonian or Campanian whereas Scaphitinae survived into the Maastrichtian (Wright et al. 1996).

Characters (from Wright et al. 1996): Coiled in loose or tight, plane spiral followed by long or short shaft and terminal hook, but shaft tending to shorten and hook may wrap around spire. Ornament varying, from almost none to strong ribs and numerous rows of tubercles. Suture initially quinquelobate followed by quadrilobate, but in later genera one or more auxiliary lobes appearing in saddle U/L; L bifid or trifid. Synaptychi known for several species. Markedly dimorphic; in Otoscaphitinae microconchs have long lateral lappets; in Scaphitinae microconchs lack such lappets. Microconchs with umbilicus less occluded by inner seam of shaft than macroconchs.

<==Scaphitidae [Scaphitaceae, Scaphitoidea]
    |--Otoscaphitinae [Worthoceratidae]WCH96
    |    |--Eorhaeboceras Alabushev 1989WCH96
    |    |    `--*E. derivatum Alabushev 1989WCH96
    |    |--Worthoceras Adkins 1928WCH96
    |    |    |--*W. platydorsum (Scott 1924) [=Macroscaphites platydorsus]WCH96
    |    |    |--W. gibbosumK79
    |    |    `--W. vermiculusWCH96
    |    `--Yezoites Yabe 1910 [incl. Hyposcaphites Wiedmann 1965, Otoscaphites Wright 1953]WCH96
    |         |--*Y. perrini (Anderson 1902) [=Scaphites perrini]WCH96
    |         |--Y. bladenensis (Schlüter 1871) [=Ammonites bladenensis, *Otoscaphites bladenensis]WCH96
    |         |--Y. puerculusWCH96 [=Otoscaphites puerculusK81]
    |         |--Y. seabeensisWCH96
    |         `--Y. stephanoceroides (Yabe 1909) [=Scaphites stephanoceroides, *Hyposcaphites stephanoceroides]WCH96
         |  i. s.: Desmoscaphites Reeside 1927WCH96
         |           `--*D. bassleri Reeside 1927WCH96
         |         Argentoscaphites Blasco de Nullo, Nullo & Proserpio 1980WCH96
         |           `--*A. mutans Blasco de Nullo, Nullo & Proserpio 1980WCH96
         |         Pteroscaphites Wright 1953WCH96
         |           `--*P. auriculatus (Cobban 1952) [=Scaphites auriculatus]WCH96
         |         Hoploscaphites Nowak 1911 [incl. Jeletzkytes Riccardi 1983, Mesoscaphites Atabekian 1979 (n. n.)]WCH96
         |           |--*H. constrictus (Sowerby 1817) [=Scaphites constrictus]WCH96
         |           |    |--H. c. constrictusP93
         |           |    `--H. c. crassusP93
         |           |--H. elatensis (Lewy 1969) [=Scaphites (Hoploscaphites) elatensis, *Mesoscaphites elatensis]WCH96
         |           |--‘Jeletzkytes’ nebrascensisHE05
         |           `--‘Scaphites (Ammonites)’ nodosus Owen 1852 [=*Jeletzkytes nodosus]WCH96
         |         Discoscaphites Meek 1870WCH96, EK02
         |           |  i. s.: D. abyssinusK79
         |           |         D. erucoideusK79
         |           |         D. mandensisK79
         |           |         D. nebrascensisK79
         |           |         D. roanensisK79
         |           |--D. (Discoscaphites)WCH96
         |           |    |--*D. (D.) conradi (Morton 1834) [=Ammonites conradi]WCH96
         |           |    `--D. (D.) cheyennensisWCH96
         |           `--D. (Trachyscaphites Cobban & Scott 1964)WCH96
         |                `--D. (*T.) redbirdensis (Cobban & Scott 1964) [=*Trachyscaphites redbirdensis]WCH96
         |         Acanthoscaphites Nowak 1911WCH96
         |           `--*A. tridens (Kner 1850) [=Scaphites tridens]WCH96
         |                |--A. t. tridensWCH96
         |                `--A. t. trispinosusWCH96
         |         Ponteixites Warren 1934WCH96
         |           `--*P. robustus Warren 1934WCH96
         |         Indoscaphites Spath 1953WCH96
         |           |--*I. cunliffei (Forbes 1846) [=Ammonites cunliffei]WCH96
         |           `--I. pavana [=Scaphites (Indoscaphites) pavana]W69
         |         Parabinneyites Leanza 1964 [=Patagoniceras Leanza 1963 non Wetzel 1960]WCH96
         |           `--*P. paynensis (Favre 1908) [=Leopoldia paynensis, *Patagoniceras paynense]WCH96
         |--Clioscaphites Cobban 1952WCH96
         |    |--*C. montanensis Cobban 1952WCH96
         |    |--C. choteauensisK79
         |    |--C. novimexicanusK79
         |    |--C. saxitonianusK79
         |    `--C. vermiformisWCH96
         `--+--Eoscaphites Breistroffer 1947WCH96
            |    |--*E. circularis (Sowerby 1836) [=Ammonites circularis]WCH96
            |    `--E. subcircularisWCH96
               |--Rhaeboceras Meek 1876W69, WCH96
               |    `--*R. halli (Meek 1876) [=Phylloceras halli, Ammonites halli Meek & Hayden 1857 (n. n.)]WCH96
               `--Haresiceras Reeside 1927W69, WCH96
                    |  i. s.: H. montanaenseK79
                    |         H. natronenseK79
                    |--*H. (Haresiceras) placentiforme Reeside 1927WCH96
                    `--H. (Mancosiceras Cobban 1964)WCH96
                         `--H. (*M.) mancosense Reeside 1927) [=Puzosia (Latidorsella) mancosensis]WCH96

*Type species of generic name indicated


[EK02] Engeser, T., & H. Keupp. 2002. Phylogeny of the aptychi-possessing Neoammonoidea (Aptychophora nov., Cephalopoda). Lethaia 35: 79–96.

[HE05] Hoganson, J. W., & J. M. Erickson. 2005. A new species of Ischyodus (Chondrichthyes: Holocephali: Callorhynchidae) from Upper Maastrichtian shallow marine facies of the Fox Hills and Hell Creek Formations, Williston Basin, North Dakota, USA. Palaeontology 48: 709–721.

[K79] Kauffman, E. G. 1979. Cretaceous. In: Robison, R. A., & C. Teichert (eds) Treatise on Invertebrate Paleontology pt A. Introduction. Fossilisation (Taphonomy), Biogeography and Biostratigraphy pp. A418–A487. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

[K81] Klinger, H. C. 1981. Speculation on buoyancy control and ecology in some heteromorph ammonites. In: House, M. R., & J. R. Senior (eds) The Ammonoidea: The evolution, classification, mode of life and geological usefulness of a major fossil group pp. 337–355. Academic Press.

[P93] Page, K. N. 1993. Mollusca: Cephalopoda (Ammonoidea: Phylloceratina, Lytoceratina, Ammonitina and Ancyloceratina). In: Benton, M. J. (ed.) The Fossil Record 2 pp. 213–227. Chapman & Hall: London.

[W69] Wiedmann, J. 1969. The heteromorphs and ammonoid extinction. Biological Reviews 44: 563–602.

[WCH96] Wright, C. W., J. H. Calloman & M. K. Howarth. 1996. Treatise on Invertebrate Paleontology pt L. Mollusca 4, revised vol. 4. Cretaceous Ammonoidea. The Geological Society of America, Inc.: Boulder (Colorado), and The University of Kansas: Lawrence (Kansas).

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