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Species Baculites ovatus Say 1820

[1]
[2]
[3]
[4]
[5]
[6]
[1] 9d-h Ifrim et al. (2005) [2] 9i-l Ifrim et al. (2005) [3] 5i-j Ifrim et al. (2005) [4] pl. 3, figs. 1-3 Ifrim et al. (2004) [5] text-fig. 11a-e Ifrim et al. (2004) [6] text-fig. 12a-d Ifrim et al. (2004)

Diagnosis / Definition:
Ifrim et al. (2005):
Description. Straight phragmocone with moderate expansion rate and ovate whorl section. The dorsum is widely rounded to flattened and passes into more or less widely rounded shoulders. Convex flanks converge towards the venter which is also rounded. Where shell is preserved, faint crescent ribs are observed dorsolaterally. Suture line with broad, moderately incised, subquadrate to moderately rounded bifid saddles and lobes with phylloid terminations. Distance between sutures varies from overlapping to full separation of lobe lines.
Ifrim et al. (2004):
Description: The test is ovate in cross section and expands moderately quickly to fast with an apical angle of c. 8 degrees. The venter is more rounded in juveniles. Convex flanks grade into a widely rounded dorsum. Maximum breadth is above the middle flank. The flank is ornamented dorsolaterally with faint crescentic ribs, which are weak or absent in juveniles but more pronounced in adult individuals (rib index about 2). These ribs cross the dorsum in a convex arch. Ribs split into straight prorsiradiate striae on the flanks. Striae bend forward shortly before the venter and are then strongly projected. The rib index of these secondary ribs is c. 4. The suture line is composed of broad, little incised and subreetangular bifid saddles with phylloid saddle terminations. The dorsal saddle is lower than the lateral saddles. Lobes are also bifid and subrectangular. Two subsequent sutures overlap deeply at the LlU saddle, but are gradually separated during ontogeny and with increasing grade of incision. In more adult phragmocones, saddles and lobes become more rounded in outline.
Discussion / Comments:
Ifrim et al. (2005):
Type: The holotype, by original designation of Say (1820, p. 41), was recorded at the Academy of Natural Sciences, Philadelphia. According to Cobban (1974, p. 4), it may be lost. Material: Six fragments from the Potrerillos Formation, 5 km north of Minas, N.L. Occurrence: Baculites ovatus has been recorded from the Late Campanian of the basal Navesinsk Formation in New Jersey (Cobban, 1974) and the Saratoga Chalk in Arkansas (Kennedy and Cobban, 1993a). In Mexico, it was described from the Maastrichtian part of the Potrerillos Formation in the La Popa Basin (Wolleben, 1977; Vega et al., 1995, but only listed), and the Early Maastrichtian of the Méndez Formation (Ifrim et al., 2004). Discussion: The ovate whorl section and weak ornamentation are characteristic of this species.
Ifrim et al. (2004):
Remarks: Some specimens assigned to B. ovatus are similar to Late Maastrichtian B. vertebralis (Lamarck, 1801). Particu1ar1y, specimens with rounded venter and distant, faint ribs look very much a1ike, but differ from B. vertebralis in having a slightly higher WB/WH ratio (e.g. UANL CE MAAS-094 and 095, Textfig. 11c-D; see also Cobban 1974b, pl. 1, figs 21, 27-31). Baculites undatus Stephenson (1941) is strong1y omamented and differs from B. ovatus in having astout, subelliptica1 whorl section and a lower rib index (primary rib index of B. undatus is c. 1). Small growth stages of B. ovatus are simi1ar to B. occidentalis (Meek 1862), but no comparison exists so far for juveniles of these two species. Baculites occidentalis is known from the uppermost Campanian-1owest Maastrichtian of Madagascar and the northem Pacific region (Ward 1978). Occurrence: Baculites ovatus Say is known to occur in the Navesinsk Formation in New Jersey (Cobban 1974b) and the Saratoga Chalk of Arkansas (Kennedy and Cobban 1993b). It has also been described from the Potrerillos Formation of the Difunta Group in north-east Mexico (Wolleben 1977; Vega et al. 1995, but only listed). The species seems to be restricted to the northern Gulf of Mexico region and the Atlantic coast of North America.
Synonym list:
Ifrim et al. (2005):
1820 Baculites ovata Say. - Say : p.41
1974 Baculites ovatus Say. - Cobban : p.3 pl. 1, figs. 1-32; pl. 2, figs. 1-14; pl. 3, figs. 1-6, 9-11; fig. 4 (with full synonymy)
1977 Baculites ovatus Say. - Wolleben : p.389 pl. 3, fig. 22
? 1990 Baculites ovatus Say. - Vega-Vera & Perrilliat : p.19 pl. 4, figs. 1-2
1993 Baculites ovatus Say. - Kennedy & Cobban : p.426 text-figs. 12.3-4, 14.5, 14.12, 14.15-17, 14.20, 14.22-42, 15.1-12, 15.14-24
1995 Baculites ovatus Say. - Vega et al. : p.347
2004 Baculites ovatus Say. - Ifrim et al. : pl. 3, figs. 1-3; text-figs. 11a-e, 12a-d
2005 Baculites ovatus Say. - Ifrim et al. : 55, 61 fig. 5i-j, fig. 9d-l
Ifrim et al. (2004):
1820 Baculites ovata Say. - Say : p.41
1974 Baculites ovatus Say. - Cobban : p.3 pl. 1, figs. 1-31; pl. 2, figs. 1-14; pl. 3, figs. 1-6, 9-11; text-fig. 4 (with full synonymy)
1977 Baculites ovatus Say. - Wolleben : p.389 pl. 2, fig. 22
1990 Baculites ovatus Say. - Vega-Vera & Perrilliat : p.19 pl. 4, figs. 1-2
1993 Baculites ovatus Say. - Kennedy & Cobban : p.426 text-figs. 12.3-4, 14.5, 14.12, 14,15-17, 14.20, 14.22-42, 15.1-12, 15.14-24
1993 Baculites ovatus Say. - Kennedy & Cobban : p.426 text-figs. 12.3-4, 14.5, 14.12, 14,15-17, 14.20, 14.22-42, 15.1-12, 15.14-24
1995 Baculites ovatus Say. - Vega et al. : p.347
2004 Baculites ovatus Say. - Ifrim et al. : 29, 30, 31 pl. 3, figs. 1-3; text-figs. 11a-e, 12a-d
Was used in synonym list of:
Baculites spp.
Stratigraphy - relative ages:
lower Maastrichtian - upper Campanian: Ifrim et al. (2005)
References:

Say,T.. (1820):
Observations on some species of zoophytes, shells, etc, principally fossil . American Journal of Science, 1st series Vol. 2 p. 34–45

Cobban,W.A.. (1974):
Ammonites from the Navesink Formation at Atlantic Highlands, New Jersey . United States Geological Survey Professional Paper Vol. 845 p. 1-46

Wolleben,J.A.. (1977):
Paleontology of the Difunta Group (Upper Cretacous– Tertiary) in northeastern Mexico . Journal of Paleontology Vol. 51(2) p. 373–398

Vega-Vera,F.J.. and Perrilliat,M.C.. (1990):
Moluscos del Maastrichtiano de la Sierra de la Antrisco, estado de Nuevo León . Paleontología Vol. 55 p. 42

Kennedy,W.J.. and Cobban,W.A.. (1993):
Ammonites from the Saratoga Chalk (Upper Cretaceous), Arkansas . Journal of Paleontology Vol. 67(3) p. 404–434

Vega,F.J..; Feldmann,R.M.. and Sour-Tovar,F.. (1995):
Fossil Crabs (Crustacea: Decapoda) from the Late Cretaceous Cárdenas Formation, eastcentral Mexico . Journal of Paleontology Vol. 69(2) p. 340-350

Ifrim,C..; Stinnesbeck,W.. and López-Oliva,J.G.. (2004):
Maastrichtian cephalopods from Cerralvo, north-eastern Mexico . Palaeontology Vol. 47(6) p. 1575–1627

Ifrim,C..; Stinnesbeck,W.. and Schafhauser,A.. (2005):
Maastrichtian shallow-water ammonites of northeastern Mexico . Revista Mexicana de Ciencias Geológicas Vol. 22(1) p. 48-64

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