Agaminae Spix, 1825
|
publication ID |
https://doi.org/10.1186/s13358-024-00332-7 |
|
persistent identifier |
https://treatment.plazi.org/id/E86287BF-FFC1-FFD5-BA71-A5EEFDEBFC24 |
|
treatment provided by |
Felipe |
|
scientific name |
Agaminae Spix, 1825 |
| status |
|
Agaminae Spix, 1825 View in CoL View at ENA
Agaminae indet.
Figure 41 View Fig
Material. Chalicorrema: one right maxilla ( UU RA 403), three dentaries ( UU RA 427– UU RA 429), two fragments of indeterminate tooth bearing bones ( UU RA 401 and UU RA 402), and five caudal vertebrae ( UU RA 404 and UU RA 430– UU RA 433).
Description.
UU RA 403 is a small bone fragment, representing the anterior end of the anterior premaxillary process of a right maxilla ( Fig. 41a, b View Fig ). In dorsal view, it has a straight anterior margin. Tere is no anterolateral process. An anteromedial process could, on the other hand, have been present in origin, but an evident breakage in the related area of the specimen hinders a clear evaluation of its possible development. Te dorsal surface of the anterior premaxillary process is strongly concave. Te specimen bears a single, well-preserved first tooth, plus fragments of a second one posteriorly. Te tooth is subpleurodont, straight and pointed. It has no striation and an unswollen base. In spite of being very poorly preserved, the second tooth also has a subpleurodont implantation. Te complete specimen is 2.4 mm long.
Tree anterior portions of dentaries are present in our material from Chalicorrema ( Fig. 41c–i View Fig ). UU RA 428
( Fig. 41f, g View Fig ) only preserves the anteriormost tip, where the subpleurodont teeth are located, whereas the other two specimens display also part of the acrodont part of the tooth row. In medial view, all specimens present a high subdental table. Te table is not distinctly developed medially in dorsal view, and bears no subdental ridge. Te Meckelian fossa is narrow and opens ventromedially. Anteriorly, the mandibular symphysis is wide. Te ventral margin of the dentaries is straight. Te lateral surface is smooth, with few anteroposteriorly-aligned mental foramina. In both most well-preserved dentaries, at least five foramina can be counted; these increase in width towards the posterior. Te dentition is heterodont, with two subpleurodont teeth followed by acrodont ones. UU RA 427 ( Fig. 41c–e View Fig ) and UU RA 429 ( Fig. 41h, i View Fig ) preserve five and three acrodont tooth positions, respectively. Only the first subpleurodont teeth in UU RA 428 ( Fig. 41f, g View Fig ) and UU RA 429 ( Fig. 41h, i View Fig ) are complete, whereas the second ones in these specimens and both ones in UU RA 427
( Fig. 41c–e View Fig ) preserve only their bases. Te most preserved subpleurodont teeth are straight, conical, non-striated, and with a rounded tip. A slightly-swollen base is visible in the first tooth of UU RA 428 ( Fig. 41f, g View Fig ). On both UU RA 427 ( Fig. 41c–e View Fig ) and UU RA 428 ( Fig. 41f, g View Fig ), the first subpleurodont tooth is clearly larger than the second one, whereas it is the opposite in UU RA 429 ( Fig. 41h, i View Fig ). Te acrodont teeth are triangular and closely packed. Ventrally, they extend to cover the underlying bone. Only in UU RA 427, distinct interdental grooves are present between each pair of acrodont teeth on the lateral surface of the bone
( Fig. 41d View Fig ). Te most preserved dentary, UU RA 427, is slightly more than 10 mm long ( Fig. 41c–e View Fig ).
Te two fragments of indeterminate tooth bearing bones from Chalicorrema are too poorly preserved to be assigned to either maxillae or dentaries ( Fig. 41j View Fig ). Tey are rather small. UU RA 402 carries one subpleurodont tooth and one acrodont tooth, whereas UU RA 401 carries two acrodont teeth and a small fragment of a third one. Te subpleurodont tooth is pointed, not swollen, and slightly posteromedially curved by the tip. It has no striae. Te acrodont ones extend on the lingual margin of the related tooth bearing bone. Tey are less preserved in UU RA 401 than in UU RA 402. In the latter specimen, the acrodont teeth are small and triangular, with no distinct accessory cusps. Teeth of UU RA 401 are larger, representing either a more posterior portion of the tooth row or an older individual. Te total length of UU RA 401 is 3.0 mm, whereas it is 2.0 mm in UU RA 402.
Te caudal vertebrae from Chalicorrema are slenderly built and elongated ( Fig. 41k, l View Fig ). Tey have wide and subelliptical anterior cotyle and posterior condyle. In anterior view, the neural canal is small, being roughly half as high as the cotyle. When preserved, the zygapophyses have subovoid and subvertical facets. Te ventral surface of the centrum is smooth, with no traces of haemapophyses or pedicles for the chevron bone. Tere is no autotomy plane. Te bases of laminar transverse processes are preserved in at least some vertebrae, being located roughly at mid-length. Te longest and most-preserved vertebra is slightly less than 10 mm long.
Remarks. An agamid is represented in the Chalicorrema assemblage by a few fragmentary fossils. Te main character supporting this identification for the tooth bearing bones is the presence of both (sub)pleurodont and acrodont teeth in the dentition (Augé, 2005; Blain et al., 2014; Delfino et al., 2008; Georgalis et al., 2023a; Moody, 1980; Smith, 2011; Smith et al., 2011; Villa & Delfino, 2019a). Another character that is commonly used to discriminate agamids from chamaeleonids is the extension of the acrodont teeth onto the lingual surface of the tooth bearing bone (Evans et al., 2002; Georgalis et al., 2023a; Villa & Delfino, 2019a). Te validity of the latter distinction was doubted by Rage and Bailon (2011), but there is no evidence indicating the presence of a chamaeleonid in Chalicorrema and thus we here refer the only tooth bearing bone fragment not presenting subpleurodont teeth to the same taxon as the other specimens due to comparable size and overall morphology of the acrodont teeth. Te presence of two subpleurodont teeth is indicative of an agamine identity of this taxon (Maul et al., 2011). Te caudal vertebrae are also attributed to Agaminae due to shared morphology with comparative specimens at our disposal (in i.e., overall elongated shape, subelliptical anterior cotyle, subvertical prezygapophyses). Te poor preservation of the remains does not allow a more precise identification. Smith et. al. (2016) reported sexual dimorphism in the size of subpleurodont teeth in the agamid Stellagama stellio (Linnaeus, 1758) , with the second tooth being larger than the first one in males. Even though identification of the Chalicorrema material is limited to the suprageneric rank, a similar variation in tooth size is observed in the three dentaries available, possibly suggesting a comparable dimorphism.
Agamidae indet.
Figure 42 View Fig
Material. Vevi: one fragment of tooth bearing bone ( UU VE 501).
Description. Te fragment of tooth bearing bone (UU VE 501) from Vevi cannot be clearly assigned to a specific element, likely being either part of a maxilla or a dentary. It bears two acrodont teeth, which are triangular and provided with an incipient accessory cusp on both mesial and distal sides ( Fig. 42 View Fig ). A low degree of wearing possibly due to tooth abrasion is visible, thus giving a rounded shape to the tip of both teeth. No distinct striae are visible on the labial and lingual sides. Te medial side of the tooth base expands ventrally to cover the alveolar surface of the tooth bearing bone. Te two teeth are separated by a distinct space. On the lateral side of the tooth bearing bone there are two vertical, deep and wide interdental grooves. Te fragment is 3.8 mm long.
Remarks. Te bone fragment from Vevi is here referred to an agamid lizard because of the widely-separated acrodont teeth, which expand ventrally on the medial side of the bone (Delfino et al., 2008; Evans et al., 2002; Georgalis et al., 2023a; Villa & Delfino, 2019a; but note possible variability, regarding features also present in chamaeleonids, reported by Rage & Bailon, 2011 and Georgalis et al., 2023a). A more precise determination of this Vevi fragment within Agamidae is not possible. It could be likely that the Vevi specimen could pertain to Agaminae , as is the more complete material from Chalicorrema described above.
| UU |
University of Uppsala |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.