Ornithocheiriformes Andres, 2021
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publication ID |
https://doi.org/ 10.4202/app.01122.2023 |
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DOI |
https://doi.org/10.5281/zenodo.13891709 |
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persistent identifier |
https://treatment.plazi.org/id/03A29F40-FFE2-2536-374D-F8E0FBE3FADF |
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treatment provided by |
Felipe |
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scientific name |
Ornithocheiriformes Andres, 2021 |
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Ornithocheiriformes Andres, 2021
Figs. 3–6 View Fig View Fig View Fig View Fig .
Material.— Twenty isolated teeth: MCF-PVPH-879-4, 879- 6, 879-8, 879-10 ( Fig. 4 View Fig ); MCF-PVPH-739-2, 743, 879-9, 880-1, 880-2, 880-3, and 880-4 ( Fig. 5 View Fig ); MCF-PVPH-741, 875, 879-1, 879-2, 879-3, 879-5, 879-7, 879-11, and 880-5 ( Fig. 6 View Fig ). All from the Cretaceous Cerro de los Leones locality, Albian, Lower Cretaceous, Picún Leufú, Argentina.
Description.—All specimens here described are represented by isolated tooth crowns with reabsorbed or lacking roots ( Fig. 3 View Fig ). In this sense, the apical wear facets, when present, and the lack of the roots do not seem to have been caused by weathering events and/or taphonomic processes, suggesting that the teeth could have been lost in life. The tooth-crowns are conidont (cone-shaped, sensu Hendrickx et al. 2015), apicobasally elongated and slightly recurved. The cross-sections are diversified in shape, subcircular, oval or elliptical. Taking into account the general morphology of the teeth, we identify three morphotypes, which are defined on the basis of three morphological features ( Table 1 View Table 1 ): tooth crown curvature, shape of the crown cross-section, and presence of carinae.
Morphotype 1.—MCF-PVPH-879-4, 879-6, 879-8, 879-10 ( Fig. 4 View Fig ). These tooth crowns are apicobasally elongated and strongly lingually recurved. The basal cross-section is subcircular, and weakly labiolingually compressed. All specimens lack carinae. In MCF-PVPH-879-4, 879-8, and 879-10 the enamel layer is fragmentary, exposing the underlying dentine layer. The dentine surface is mainly smooth, but several transversal and longitudinal fractures are present, especially on the lingual and apical surfaces. The preserved enamel surface is slightly wrinkled, showing a set of anastomosed, apicobasally extended ridges and grooves, which are more pronounced basally and progressively weaker apically. On the other hand, MCF-PVPH-879-6 preserves small fragments of enamel on the labial and lingual surfaces, resulting in an almost smooth surface. The specimens where the apical portion is preserved (MCF-PVPH-879-6 and 879-8) show wear facets in apical, labial or mesial position. In MCF-PVPH-879-8 the apical wear facet is wide and rounded, extending basally to the half of the crown ( Fig. 4 View Fig ).
Morphotype 2.—MCF-PVPH-739-2, 743, 879-9, 880-1, 880-2, 880-3, and 880-4 ( Fig. 5 View Fig ). These tooth crowns are slightly lingually recurved and almost straight in mesial view. The basal cross-section is elliptical, with a labiolingual compression. The dentine surface is almost smooth. MCF-PVPH-739-2 is incomplete, lacking part of the basal and apical portion, whereas small and smooth patches of enamel are preserved on the labial surface of the crown. Conversely, the surface of MCF-PVPH-743 is slightly wrinkled on the lingual side of the crown base, whereas in MCF-PVPH-880-1 it has several longitudinal grooves that fade apically ( Fig. 5 View Fig ). The crowns show different wear facets, of which the apical is rounded and wide, whereas the mesial and distal ones are narrower and apicobasally extended. All the specimens, except MCFPVPH-879-9, have both distal and mesial carinae, without denticles. MCF-PVPH-879-9 is incomplete, lacking part of the basal and apical portions. Moreover, it seems to have only one distal carina; however, taking into account that the crown is heavily weathered, without most of the dentine and the enamel surface, especially on the mesial surface, the loss of the mesial carina due to diagenetic process should be taken into consideration.
Morphotype 3.—MCF-PVPH-741, 875, 879-1, 879-2, 879-3, 879-5, 879-7, 879-11, and 880-5 ( Fig. 6 View Fig ). These tooth crowns are more recurved distally than lingually, with oval, labiolingually compressed cross-sections, and smooth dentine surfaces. The apical wear facet is rounded, worn at the apex from multiple directions, especially mesially and distally. All the specimens lack carinae. MCF-PVPH-875 preserves two portions of smooth enamel on the labial and distal surfaces, whereas in MCF-PVPH-879-2 the enamel is well preserved, especially on the basal half of the crown, and wrinkled, showing several apicobasally oriented and anastomosed ridges and grooves, slightly deeper on the lingual surface. A similar condition is observed on the preserved enamel of MCF-PVPH-879-1, 879-5, and 880-5, whereas in MCF-PVPH-879-3 the enamel is apically worn, with apicobasally oriented grooves on the basal half of the crown. The crowns of MCF-PVPH-875, 879-2, and 879-3 feature labial wear on their apexes and mesial and distal wear that visibly rounds their apices.
MCF-PVPH-741 shows a wide and smooth groove, slightly deeper basally and apicobasally extended to the apical third of the crown.
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