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Species Sphenodiscus lobatus Tuomey 1854 | ||||||||||||||||||||||
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[1] 4d-g Ifrim et al. (2005) [2] 6 Ifrim et al. (2005) [3] Ifrim et al. (2005) [4] 5a-d Ifrim et al. (2005) | ||||||||||||||||||||||
Diagnosis / Definition: | ||||||||||||||||||||||
Ifrim et al. (2005): Description. Compressed, involute, oxycone shell with a tiny umbilicus of about 3% of the diameter. The venter is fastigiate or narrowly rounded and grades into slightly convex flanks. Maximum whorl breadth is at midflank. Towards the umbilicus the flank is slightly concave. The shell surface is smooth or may bear faint, low, broad, concave ribs which are crescent on the outer flank but, straight on the inner flank where visible. Our material contains some body chambers, but no complete aperture is preserved. The first lateral saddle of the suture line, E/L, is trifid, auxiliary saddles are numerous and entire with the exception of the outer one or two. Cobban & Kennedy (1995): DESCRIPTION.- Fragments rare in Prairie Bluff Chalk; most are short sections of phragmocone that have whorl heights of up to 75 mm, derived from oxycone shells with whorl breadth to height ratios of around 0.4. Shell surface smooth, or may bear faint, low, broad, concave, crescentic ribs on outer flank. Sutures include trifid first lateral saddle, and up to 10 auxiliary saddles on umbilical lobe, eight of which may have entire terminations. Other saddles narrow stemmed with variously incised sometimes subphylloid terminations. Kennedy & Cobban (1996): DESCRIPTION.- All specimens fragmentary internal molds of phragmocones with whorl heights of up to 110 mm. Earliest growth stages seen represented by NJSMl1328a, a juvenile with estimated original diameter of 23-24 mm. In this and other fragments shell is very compressed and oxycone; surface of mold smooth or with traces of morsiradiate striae and riblets. Suture line includes numerous aixiliary and adventitious elements, as is typical for genus. Landman et al. (2004): DESCRIPTION.- MAPS A2002a9 is one-third whorl of a large phragmocone (not illustrated). The whorl width and height at the adoral end of the specimen are approximately 66.6 mm and 164.0 mm, respectively; the ratio of whorl width to height is 0.41. The flanks are very broadly rounded and converge to an acute venter. Part of the suture on the adapical end of the specimen is illustrated (fig. 25A). MAPS A2002a8 is a large specimen, 285 mm in diameter, with the adoral end slightly crushed in (figs. 23, 24). Most of the specimen is phragmocone with barely less than one-eighth whorl of body chamber attached. However, part of the rest of the body chamber was still present but was not collected in the field because it was too crushed. Three oval to circular depressions appear on the midflanks of the body chamber on the left side, the largest of which is approximately 16 mm in diameter. The inner flanks are nearly flat and slightly divergent, the midflanks are very broadly rounded and subparallel, and the outer flanks are nearly flat and converge to an acute venter. The whorl width and height near the base of the body chamber are approximately 35.2 mm and 170 mm, respectively, although the whorl width is underestimated due to crushing; the ratio of whorl width to height is 0.21. The flanks are smooth without any nodes. The suture has a very broad and shallow external lobe with a low, little incised median saddle (fig. 25B). |
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Discussion / Comments: | ||||||||||||||||||||||
Ifrim et al. (2005): Type: The holotype is lost (fide Stephenson, 1941, p. 434). It was from Noxubee County, Mississippi. Material: 34 specimens from the Cerro del Pueblo Formation at Rincón Colorado, Coahuila. Occurrence: This Maastrichtian species was described from the Escondido Formation in northeastern Mexico and Trans-Pecos, Texas (Böse, 1928), Alabama, and Mississippi (Cobban and Kennedy, 1995), and northeast Texas (Kennedy and Cobban, 1993b). Other records are from North Carolina, Maryland, New Jersey, Israel and Nigeria (fide Cobban and Kennedy, 1995). In the Western Interior, S. lobatus was recorded from the Hoploscaphites nicolletii and Jeletzkytes nebrascensis ammonite zones and may also exist in the H. birkelundi zone (see Kennedy et al., 1997). Discussion: According to Cobban and Kennedy (1995) and Kennedy et al. (1997), this species is morphologically variable. Kennedy et al. (1997) include S. lenticularis intermedius into the synonymy of S. lobatus. Sphenodiscus pleurisepta, another common species in the Gulf of Mexico area, clearly differs by a stronger ornamentation. Cobban & Kennedy (1995): TYPE.- The holotype, from Noxubee County, Mississippi, is lost (tide Stephenson, 194 1, page 434). MATERIAL.- Five specimens, USNM 463 109-463 1 14. DISCUSSION.- A second Sphenodiscus present in the Prairie Bluff Chalk is S. pleurisepta (Conrad, 1857, page 159, plate 15, figure 1; see below). This differs from S. lobatus in having midlateral and outer lateral tubercles when young linked by sickle shaped ribs. The outer lateral tubercle develops into a crescentic rib in middle and later growth. OCCURRENCE.- Maastrichtian, Prairie Bluff Chalk at locality 45 in Wilcox County, Alabama, and at localities 21 and 24 in Noxubee County, Mississippi. It also occurs in the Escondido Formation in Trans-Pecos Texas and northern Mexico; Corsicans Formation in northeast Texas; upper part of Ripley Formation in Mississippi; Providence Sand in the Chatahoochee River area of eastern Alabama; Peedee Formation in North Carolina; Severn Formation in Maryland; Red Bank Sand and Tinton Sand of New Jersey; and in the Western Interior. Elsewhere, the species is known from Israel and Nigeria. Kennedy & Cobban (1996): TYPE.- The holotype, from Noxubee County, Mississippi, is lost (fide Stephenson, 1941, p. 434). DISCUSSION.- See Cobban and Kennedy (1995) for a discussion of the present species and its synonyms and differences from allied species. MATERIAL.- More than 50 fragments including NJSM 103 15, 11328a-z, cc, ee, ff, from the main fossiliferous layer of the Hornerstown Formation at the Inversand Marl Pit, Gloucester County, New Jersey. OCCURRENCE.- Escondido Formation in Trans-Pecos Texas and northern Mexico; Corsicana Formation in northeast Texas; upper part of Ripley Formation in Mississippi; Prairie Bluff Chalk in Alabama and Mississippi; Providence Sand in the Chattahoochee River area, Alabama and Georgia; upper part of Peedee Formation in North Carolina; Severn Formation in Maryland; Red Bank Sand and Tinton Sand in New Jersey. In the Western Interior the species occurs in the Hoploscaphites nicolletii and Jeletzkytes nebrascensis zones, and may also be present in the underlying H. birkelundi zone. Landman et al. (2004): TYPE.- The holotype, from Noxubee County, Mississippi, is lost (fide Stephenson, 1941: 434). MATERIAL.- There are two specimens: MAPS A2002a8 and A2002a9 from the Tinton Formation, AMNH loc. 3348, 0.2 km north of the intersection of Water Street and Tinton Avenue, Tinton Falls, Monmouth County, New Jersey. DISCUSSION.- These specimens lack the two rows of nodes characteristic of Sphenodiscus pleurisepta and are referred to Sphenodiscus lobatus. Cobban and Kennedy (1995) fully discussed S. lobatus and the differences with congeneric species. The shallow circular depressions and crushed body chamber may indicate predation. OCCURRENCE.- Tinton Formation, near Tinton Falls, northeastern Monmouth County, New Jersey (Weller, 1907; Reeside, 1962; see also Gallagher, 1993). Sphenodiscus lobatus has also been reported in New Jersey from the MFL at the Inversand Marl Pit, Gloucester County (Gallagher, 1993; Kennedy et al., 1995; Kennedy and Cobban, 1996). Elsewhere on the Gulf and Atlantic Coastal Plains, this species is known from the Corsicana Formation in northeast Texas (Kennedy and Cobban, 1993); the upper part of the Ripley Formation in Mississippi; the Prairie Bluff Chalk in Alabama and Mississippi (Cobban and Kennedy, 1995); the Providence Sand in the Chattahoochee River area, Alabama and Georgia; the upper part of the Peedee Formation in North Carolina (Landman et al., 2004); and the Severn Formation in Prince Georges County, Maryland (Kennedy et al., 1997). It is known from the Escondido Formation in Trans-Pecos Texas and northern Mexico (Stephenson, 1941, 1955). In the Western Interior, this species occurs in the Hoploscaphites nicolletii and Jeletzkytes nebrascensis Zones of the Fox Hills Formation in north-central South Dakota (Landman and Waage, 1993) and in the J. nebrascensis Zone of the Pierre Shale in southeastern South Dakota and northeastern Nebraska (Kennedy et al., 1998). |
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Systematics: | ||||||||||||||||||||||
36 Ordo Ammonoidea Subordo Ammonitina Superfamilia Acanthocerataceae Familia Sphenodiscidae Subfamilia Sphenodiscinae Genus Sphenodiscus Species Sphenodiscus lobatus 44 Classis Cephalopoda Subclassis Nautiloidea Ordo Ammonoidea Subordo Ammonitina Superfamilia Acanthocerataceae Familia Sphenodiscidae Genus Sphenodiscus Species Sphenodiscus lobatus 46 Ordo Ammonoidea Subordo Lytoceratina Superfamilia Acanthocerataceae Familia Sphenodiscidae Species Sphenodiscus lobatus 48 Ordo Ammonoidea Subordo Ammonitina Superfamilia Acanthocerataceae Familia Sphenodiscidae Genus Sphenodiscus Species Sphenodiscus lobatus |
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Synonym list: | ||||||||||||||||||||||
Ifrim et al. (2005): 1852 Ammonites lenticularis Owen. - Owen : p.579 pl. 8, fig. 5
1854 Ammonites lobata Tuomey. - Tuomey : p.168
1928 Sphenodiscus lenticularis Owen. - Böse : p.293 pl. 14, figs. 9-11
1941 Sphenodiscus tirensis Stephenson. - Stephenson : p.435 pl. 93, figs. 1-3; pl. 94, figs. 1-2
1995 Sphenodiscus lobatus Tuomey. - Cobban & Kennedy : p.12 figs. 6.2-6.3, 8.4, 8.6-8.11, 12.18-12.19, 16.16-16.17
1996 Sphenodiscus lobatus Tuomey. - Kennedy & Cobban : p.802 figs. 2.4-2.6, 2.13-2.14, 2.19-2.21
1997 Sphenodiscus lobatus Tuomey. - Kennedy et al. : p.4 figs. 3-8,9a-i,10
2005 Sphenodiscus lobatus Tuomey. - Ifrim et al. : 54, 55, 57, 59 figs. 4d-g; 5a-d, 6a-e, 7d-f
Cobban & Kennedy (1995): 1852 Ammonites lenticularis Owen. - Owen : p.579 pl. 8; fig. 5
1854 Ammonites lobatus Tuomey. - Tuomey : p.168
1871 Ammonites (Sphenodiscus) lobatus Tuomey. - Meek : p.298
1876 Placenticeras (Sphenodiscus) lobatus Tuomey. - Meek : p.473 pl. 34, fig. 1;
text-fig. 66
1892 Ammonites (Sphenodiscus) lobatus Tuomey. - WHITFIELD : p.258 pl. 41; fig 8, 9
1894 Sphenodiscus lenticularis Owen. - Grossouvre : p.139 text-fig. 56
1903 Sphenodiscus lenticularis Owen. - Hyatt : p.71 pl. 8, fig. 1, 2;
pl. 9, fig. 1-6
1903 Sphenodiscus lobatus Tuomey. - Hyatt : p.66 pl. 6, fig. 1, 2;
pl. 7, fig. 1, 2;
pl. 9, fig. 11-13
1903 Sphenodiscus lenticularis var. splendens Hyatt. - Hyatt : p.75 pl. 8, fig. 3-7
1903 Sphenodiscus lenticularis var. mississippiensis Hyatt. - Hyatt : p.77 pl. 9; fig. 7-9
1903 Sphenodiscus stantoni Hyatt. - Hyatt : p.70 pl. 5, fig. 4,
pl. 6, fig. 5
1903 Sphenodiscus beecheri Hyatt. - Hyatt : p.78 pl. 6, fig. 3, 4;
pl. 9, fig. 10
1908 Sphenodiscus lenticularis Owen. - Grossouvre : p.20 pl. 1, fig. 6;
text-fig. 5-8
1908 Sphenodiscus lobatus Tuomey. - Grossouvre : p.20 pl. 1; fig. 7
1910 Sphenodiscus lenticularis Owen. - Grabau & Shimer : p.216 fig. 1491a-c
1910 Sphenodiscus lobatus Tuomey. - Grabau & Shimer : p.216
1912 Sphenodiscus lenticularis Owen. - Douville : p.317 text-fig. 67
1913 Sphenodiscus lenticularis Owen. - Böse : p.20 pl. 1; fig. 2-5
1916 Sphenodiscus lobatus Tuomey. - Gardner : p.388 pl. 13; fig. 10
1919 Sphenodiscus lenticularis Owen. - SALFELD : p.456 pl. 1; fig. 16
1923 Sphenodiscus lobatus var. allisonensis Stephenson. - Stephenson : p.397 pl. 99; fig. 1, 2
1928 Sphenodiscus lenticularis Owen. - Böse : p.293 pl. 14; fig. 9-11
1929 Sphenodiscus n sp. aff. stantoni Hyatt. - Picard : p.451 text-fig. 11
1938 Sphenodiscus lenticularis Owen. - Roman : p.504
1938 Sphenodiscus lobatus Tuomey. - Roman : p.503 pl. 53; fig. 493, 493a
1941 Sphenodiscus tirensis Stephenson. - Stephenson : p.435 pl. 93, fig. 1-3,
pl. 94, fig. 1, 2
1945 Sphenodiscus lenticularis Owen. - Morgan & Petsch : pl. 5; fig. 3
1952 Sphenodiscus lenticularis Owen. - Basse : pl. 1; fig. 12, fig. 14 on p. 601
1955 Sphenodiscus aff. lobatus Tuomey. - Reyment : p.87 pl. 22, fig. 1;
text-fig. 44
1962 Sphenodiscus lobatus Tuomey. - Reeside : p.136 pl. 74, fig. 1;
pl. 75, fig. 3
1982 Sphenodiscus lobatus lobatus Tuomey. - Zaborski : p.316 fig. 21, 24, 25
1982 Sphenodiscus lobatus costatus Zaborski. - Zaborski : p.320 fig. 22, 23, 26-35
1993 Sphenodiscus lobatus Tuomey. - Kennedy & Cobban : fig. 3a, v
1995 Sphenodiscus lobatus Tuomey. - Cobban & Kennedy : p. 9, 11, 19, 24 fig. 6.2, 6.3, 8.4-8.11, 12.18, 12.19, 16.16, 16.17
Kennedy & Cobban (1996): 1852 Ammonites lenticularis Owen. - Owen : p.579 pl. 8; fig. 5
1854 Ammonites lobatus Tuomey. - Tuomey : p.168
1995 Sphenodiscus lobatus Tuomey. - Cobban & Kennedy : p.12 fig. 6.2, 6.3, 8.4, 8.6-8.11, 12.18, 12.19, 16.16, 16.17 [with full synonymy]
1996 Sphenodiscus lobatus Tuomey. - Kennedy & Cobban : p.800 fig. 2.4-2.6, 2.13, 2.14, 2.19-2.21
Landman et al. (2004): 1852 Ammonites lenticularis Owen. - Owen : p.579 pl. 8; fig. 5
1856 Ammonites lobatus Tuomey. - Tuomey : p.168
1995 Sphenodiscus lobatus Tuomey. - Cobban & Kennedy : p.12 fig. 6.2, 6.3, 8.4, 8.6-8.11, 12.18, 12.19, 16.16, 16.17 [with full synonymy]
1996 Sphenodiscus lobatus Tuomey. - Kennedy & Cobban : p.802 fig. 2.4-2.6, 2.13, 2.14, 2.19-2.21
1997 Sphenodiscus lobatus Tuomey. - Kennedy et al. : p.4 fig. 3-8, 9A-I, 10
2004 Sphenodiscus lobatus Tuomey. - Landman et al. : p. 52-54 fig. 23-25
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Stratigraphy - relative ages: | ||||||||||||||||||||||
Maastrichtian, Ifrim et al.: () |
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References: | ||||||||||||||||||||||
Owen,D.D.. (1852): Tuomey,M.. (1854): Tuomey,M.. (1856): Meek,F.B.. (1871): Meek,F.B.. (1876): WHITFIELD,R.P.. (1892): Grossouvre,d.A.. (1894): Hyatt,A.. (1903): Grossouvre,d.A.. (1908): Grabau,A.W.. and Shimer,H.W.. (1910): Douville,H.. (1912): Böse,E.. (1913): Gardner,J.. (1916): SALFELD,H.. (1919): Stephenson,L.W.. (1923): Böse,E.. (1928): Picard,L.. (1929): Roman,F.. (1938): Stephenson,L.W.. (1941): Stephenson,L.W.. (1941): Morgan,R.E.. and Petsch,B.C.. (1945): Basse,E.. (1952): Reyment,R.A. (1955): Reeside,J.J.B.. (1962): Zaborski,P.M.P.. (1982): Kennedy,W.J.. and Cobban,W.A.. (1993): Cobban,W.A.. and Kennedy,W.J.. (1995): Kennedy,W.J.. and Cobban,W.A.. (1996): Kennedy,W.J..; Landman,N.H.. and Cobban,W.A.. (1997): Landman,N.H..; Johnson,R.O.. and Edwards,L.E.. (2004): Ifrim,C..; Stinnesbeck,W.. and Schafhauser,A.. (2005): |
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Anonymous: Unedited TaxonConcept data | ||||||||||||||||||||||
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Taxon relations
Ranking (experimental) |