Pristiophorus, MULLER AND HENLE, 1837
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publication ID |
https://doi.org/ 10.5070/P939056976 |
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publication LSID |
lsid:zoobank.org:pub:13E6A6E9-DE0F-4C71-BE40-2957F48D9F70 |
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persistent identifier |
https://treatment.plazi.org/id/03DF0849-4132-FFC1-3DDE-F9E2FB12F910 |
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treatment provided by |
Felipe |
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scientific name |
Pristiophorus |
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PRISTIOPHORUS MÜLLER AND HENLE, 1837 View in CoL PRISTIOPHORUS SP.
FIG. 6I, K View Figure 6
Type species — Pristis cirratus Latham, 1794 ; Recent , Port Jackson, New Holland .
Referred specimen (n=1) —SC2015.29.20.
Description —The specimen is an incomplete crown measuring 1 mm in width as preserved. Although the mesial side is missing, the crown was mesio-distally wide. There is a large, medially located, distally inclined, pointed cusp, which is flanked by perpendicular lateral heels (not preserved on the mesial side). The labial face is weakly convex and covered with smooth enameloid, and the labial crown foot appears to have been uniformly convex ( Fig. 6K View Figure 6 ). The lingual face is separated from the labial face by a continuous, smooth cutting edge that curls slightly lingually at its distal end ( Fig. 6I View Figure 6 ). The lingual crown face is convex and there is a short lingually directed medial protuberance.
Remarks —The fossil record of sawsharks consists predominantly of isolated rostral spines, and three Cenozoic genera have been identified. These include the extant Pristiophorus Müller and Henle, 1837 (which has smooth rostral spines) and Pliotrema Regan, 1906b (which has serrations on the posterior edge of the rostral spines), and extinct Ikamauius Keyes, 1979 (which has serrations on the anterior and posterior edges of the spine). Teeth of Ikamauius are unknown, but those of Pliotrema have a distinctive labial uvula that is clearly separated from the remainder of the crown foot ( Reinecke et al. 2020, Weigmann et al. 2020). In contrast, the labial crown foot of Pristiophorus teeth is straight to uniformly convex ( Steurbaut and Herman,1978, Engelbrecht et al. 2020, Reinecke et al. 2020).
Although broken, SC2015.29.20 appears to have had a uniformly convex labial crown foot, indicating it is Pristiophorus as opposed to Pliotrema . Müller (1999) documented Pristiophorus sp. from the Oligocene Old Church Formation of Virginia, and SC2015.29.20 represents the first fossil record of the genus in South Carolina. Pristiophorus remains are known from Eocene to Pliocene-aged deposits of the Pacific ( Welton 1972, Philips et al. 1976, Barnes et al. 1981, Olson and Welton 1986) and Atlantic ( Case 1980, Müller 1999, Purdy et al. 2001) coastal plains. Unfortunately, the poor preservation of the single specimen available to us inhibits meaningful comparison to the several described Oligo-Miocene species ( Steurbaut and Herman 1978, Reinecke et al. 2020).
BATOMORPHII CAPPETTA, 1980a RAJIFORMES BERG, 1940
RAJINAE (SENSU MCEACHRAN AND DUNN, 1998)
RAJA MCCOLLUMI CICIMURRI AND KNIGHT 2009a
FIG. 7A–D View Figure 7
Type species — Raja batis Linnaeus, 1758 View in CoL ; Recent.
Referred specimens (n=56) —SC2007.36.29, SC2007.36.30, SC2007.36.31 ( Fig. 7C, D View Figure 7 ) SC2007.36.32,
SC2007.36.131 (two teeth), SC2007.36.132 ( Fig. 7A, B View Figure 7 ), SC2007.36.148 (three teeth), SC2007.36.154 (three teeth), SC2007.36.155 (ten teeth), SC2007.36.156 (two teeth), SC2007.36.157, SC2007.36.158, SC2007.36.218, SC2007.36.219(four teeth),SC2007.36.220,SC2007.36.241, SC2015.29.3, SC2015.29.4, SC2015.29.12, SC2015.29.33 (eight teeth), SC2015.29.34, SC2015.29.35, SC2015.29.37, SC2015.29.38 (two teeth), SC2015.29.39, SC2015.29.40,
SC2015.29.41 (three teeth).
Remarks —This taxon was erected by Cicimurri and Knight (2009a) based on several hundred specimens from the Chattian Chandler Bridge Formation of South Carolina. Male and female morphologies were described, and both morphotypes are represented in the Ashley Formation sample. Müller (1999) reported Raja sp. 1 from the Ashley Formation and the Oligocene Old Church Formation of Virginia, but Cicimurri and Knight (2009a) could not determine if that material was conspecific with R. mccollumi . However, our direct comparison of Ashley Formation teeth to R. mccollumi from the Chandler Bridge Formation (SC2005.2) leads us to conclude that they are indeed conspecific. Thus, the paleobiogeographic range of R. mccollumi is herein extended to the Oligocene Salisbury Embayment of Virginia. Müller (1999) noted large numbers of Raja teeth in the Oligocene samples he examined, and our analyses indicate that the taxon was also common in South Carolina during the Oligocene.This diminutive species is easily missed unless a #20 (0.8 mm) or finer screen is used to process matrix.
The R. mccollumi male morphology ( Fig. 7A, B View Figure 7 ) clearly differs from that of Atlantoraja cecilae ( Steurbaut and Herman, 1978) from the Oligocene of Europe by having a less laterally compressed cusp that bears short apical carinae on the mesial and distal sides. Male teeth of Raja thiedei Reinecke, 2015 from the Chattian of Germany, although of comparable size to R. mccollumi , have more elongated lateral cutting edges, a depressed rather than convex area below the labial cusp base, and the lingual crown foot is more expansive. We herein retain the mccollumi species within Raja following Reinecke (2015) but note that they could represent one of the many skate genera that were once assigned to Raja (see McEachran and Dunn 1998). For example, A. cecilae was originally assigned to Raja by Steurbaut and Herman (1978) but placed within Atlantoraja by Reinecke (2015).
“ RAJA ” SP.
FIG. 7E–H View Figure 7
2009a Raja sp. ; Cicimurri and Knight, page 637, fig. 7A–B.
Referred specimens (n=18) —SC2007.36.33 ( Fig. 7E, F View Figure 7 ), SC2007.36.34, SC2007.36.35, SC2007.36.36, SC2007.36.37, SC2007.36.38, SC2007.36.124 ( Fig. 7G, H View Figure 7 ), SC2007.36.150 (two teeth), SC2007.36.151, SC2007.36.221 (two teeth), SC2007.36.222, SC2007.36.223, SC2007.36.242, SC2015.29.5, SC2015.29.15, SC2015.29.36.
Remarks —These teeth appear to be conspecific with Raja sp. of Cicimurri and Knight (2009a) from the Chattian Chandler Bridge Formation. The low-crowned teeth in our Ashley Formation sample, as well as low-crowned teeth of the Raja sp. reported by Cicimurri and Knight (2009a), have a small, medially located cusp, which is lingually directed and may be distally inclined ( Fig. 7G, H View Figure 7 ). A sharp transverse ridge may extend across the entire width of the tooth (including the cusp), but on some teeth the transverse cutting edge is best developed on the mesial and distal sides of the crown, but it becomes inconspicuous at the base of the cusp and is not evident apically.
Other teeth in the sample have a very tall and conical cusp that curves lingually, and cutting edges are restricted to the postero-mesial and postero-distal sides of the upper part of the cusp ( Fig. 7E, F View Figure 7 ). We interpret this variation in tooth morphology to reflect gynandric heterodonty, with the low-crowned, weakly cuspidate teeth representing females, and those teeth with distinctive conical cusps being from male individuals. Differences in cusp inclination likely reflect jaw position, with erect and symmetrical teeth occupying more anterior files, whereas those with a distally directed cusp occupying more lateral positions.
It is interesting to note that a large skate taxon ( Raja sp. ) is coeval with a smaller taxon ( R. mccollumi ) in both the Ashley Formation and overlying Chandler Bridge Formation. This scenario has also been documented in the Oligocene of Europe, where Atlantoraja cecilae (equivalent in size to R. mccollumi ) and Dipturus casieri ( Steurbaut and Herman, 1978) co-occur ( Steurbaut and Herman 1978, Müller 1983, Hovestadt and Hovestadt-Euler 1995, Reinecke et al. 2005). The latter taxon was originally identified as Raja casieri by Steurbaut and Herman (1978), but the species was recently referred to Dipturus by Reinecke (2015) because of the presence of transverse cutting edges on male and female teeth ( Herman et al. 1995). It is possible that the Raja sp. teeth from both the Ashley and Chandler Bridge Formations represent a species of Dipturus , but this seems unlikely because the male teeth in our sample lack complete cutting edges, and neither male nor female teeth possess a low cusplet at the mesial and/or distal crown foot ( Herman et al. 1995, Reinecke 2015). These features, combined with the uniformly convex labial margin, preclude assignment of these Oligocene teeth to Rostroraja Hulley, 1972 ( Herman et al. 1995). These Ashley Formation teeth are similar to extant Bathyraja Ishiyama, 1958 and Rajella lintea ( Fries, 1838) ( Herman et al. 1995) , but for the purposes of this report we tentatively assign them to Raja due to the lack of comparative skeletal material.
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