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Hummelichelys
Taxonomy
Hummelichelys was named by Chkhikvadze (2000).
It was assigned to Trionychidae by Chkhikvadze (2000).
It was assigned to Trionychidae by Chkhikvadze (2000).
Synonymy list
| Year | Name and author |
|---|---|
| 2000 | Hummelichelys Chkhikvadze |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
G. †Hummelichelys Chkhikvadze 2000
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| V. M. Chkhikvadze 2000 | Nuchal is moderately wide, narrow or very narrow (extreme variants: sagatus and reesidei); shape of this plate is also variable – its anterior margin either strongly projecting forward or abrupted (extreme variants: sagatus, grangeri – from one side and subquadratus, robustus from other side). There are 8 pairs of costals (the most wedge-shaped are II and V). VII and VIII costals are the smallest. Costals and neurals strongly reduced in the caudal part of the carapace. These are VII and VIII pairs of costals and VI, VII and VIII neurals, of which VIII neural, probably, always absent (with exception of singularis; see below for details); VII neural usually also absent (in reduced condition this plate present in several species only), and VI neural always present. In all cases the last neural has subtrigonal or subpentagonal shape. All (other – I. D.) neurals are hexagonal and, as a rule, all has short sides posteriorly (this character also shared by Plastomenus and Paleotrionyx). Tetragonal neural (if present) is V or VI. Significant decreasing in size of neurals in posterior direction is also characteristic for this genus (shared by Plastomenus).
Plastra of Hummelichelys is similar with plastra of recent Apalone sensu stricto on the one side and with Zangerlichelys and Paleotrionyx on the other (see below). Usually the medial fontanelle between the hyoplastra and hypoplastra is well developed with exception of “Plastomenus” robustus, in which it absent. This case represent the direct analogue with Apalone ferox. In old individuals of this species, unlike young and adults, such fontanelle is absent. Antero-medial process of hypoplastron usually well separated from other medial processes (with exception of late Cretaceous foveatus, which has relatively weak separation of this process). Antero-medial process of hyoplastron also weakly developed; it is clearly shorter, than in Paleotrionyx. Xiphiplastra are relatively short (annae) or elongated (guttatus); their external surface is covered with ornamentation. |