Atractosteus sp.
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publication ID |
https://doi.org/ 10.4202/app.01117.2023 |
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persistent identifier |
https://treatment.plazi.org/id/03E18741-1309-EF0D-DC22-FCA6FAB8FD57 |
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treatment provided by |
Felipe |
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scientific name |
Atractosteus sp. |
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Fig. 3H View Fig .
Material.— Eleven teeth ( SOM 1 : table 1): two (RU-EFP-00265-2, 268-2) from the lower Hornerstown Formation below the MFL; five (RU-EFP-00159-3, 2761, 2939, 2970, 4068) from the MFL; one (RU-EFP-00234-1) from the lower Hornerstown Formation above the MFL; and three (RU- EFP-00157-23, 3374, 4152) collected as float. All from the Maastrichtian– Danian Hornerstown Formation , Edelman Fossil Park, Mantua Township, New Jersey, USA .
Description.—The teeth are apicobasally tall and exhibit the plicidentine structure unique to lepisosteids ( Grande 2010): a circular cross section with longitudinal striae/grooves present along the lower half of the dentine tooth base. The enameled crown is restricted to the tip of the tooth and comprises 10% or less of the apicobasal height; its ventral border is broadly concave in labial and lingual views. The crown is lanceolate in form, being labiolingually flattened with distinct, unserrated carinae along the mesial and distal edges that gently curve inward to meet the dentine at their bases. This morphology gives the impression of a slight constriction beneath the crown, but it is actually due to broadening of the basal crown rather than narrowing of the subjacent dentine. The tip of the crown forms a rounded, obtuse angle in most specimens, but one exhibits a semicircular profile without an angled apex.
Remarks.—Plicidentine tooth structure and enamel restricted to the tip of the crown identify these teeth as belonging to a lepisosteid gar ( Grande 2010). Among lepisosteids, only Lepisosteus Lacépède, 1803 , and Atractosteus possess tall, fang-like teeth ( Grande 2010). Though teeth of these genera are morphologically similar in most respects, Atractosteus possesses more lanceolate, bladelike crowns with a slight constriction beneath the enamel tip ( Sigé et al. 1997; Szabó et al. 2016); whereas the enamel tip in Lepisosteus is rounder and lacks such constriction ( Grande 2010). We therefore refer the teeth described here to Atractosteus . At present, no features of the teeth are known to be diagnostic at the species level, so we refer the specimens to Atractosteus sp.
Fossils of gars have previously been described from the Cretaceous of New Jersey, including remains of Lepisosteus collected from the Campanian Marshalltown, Wenonah, and Mount Laurel formations ( Gallagher 1993) and Atractosteus material from the Marshalltown Formation at Ellisdale ( Denton et al. 1996). Scales of an indeterminate lepisosteid have also been recovered from the basal portion of the Maastrichtian Navesink Formation at Holmdel Park in Monmouth County ( Callahan et al. 2014). The six teeth described here thus constitute the first gar fossils from the Hornerstown Formation and include the first records of Atractosteus in the Paleocene (Danian) in New Jersey and a new addition to the fauna of Edelman Fossil Park.
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