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Exilia stechesonae (snail)
Taxonomy
Exilia stechesonae was named by Squires and Stecheson (2017) [The correct authorship for this taxon is "Squires in Squires & Stecheson, 2017".]. Its type specimen is LACMIP 10715.19 (=LACMIP Type 10496), a shell, and it is a 3D body fossil. Its type locality is CIT loc. 1159, Dayton Canyon, which is in a Campanian marine siliciclastic in the Chatsworth Formation of California.
Sister species lacking formal opinion data
Synonymy list
| Year | Name and author |
|---|---|
| 2017 | Exilia stechesonae Squires and Stecheson p. 236 figs. 2-19 |
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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.
†Exilia stechesonae Squires and Stecheson 2017 [snail]
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| R. L. Squires and M. S. Stecheson 2017 | Shell approximately 10 to 101 mm height; most shells 15 to 55 mm height. Height/width ratio ranges from 3.2 to 5.3. Fusiform, long and narrow to moderately short and moderately wide. Spire high to, less commonly, short. On unbroken specimens, height of spire commonly greater than height of aperture. Spire outline evenly tapered or knobby/angulate. Spire (pleural) angle 13° to approximately 30°. Protoconch smooth, 0.8 to 3 whorls (paucispiral or multispiral), depending on larval development. Teleoconch with up to approximately eight or nine whorls, or, much less commonly, four to five whorls. Whorls convex (rarely somewhat flat-sided), with convexity weak to moderately strong; whorls can be angulate (rarely tabulate). Sculpture varies considerably in strength, from very weak to strong. Most shells with obvious sculpture (especially on spire), whereas some shells overall smooth- looking. Axial ribs weak to strong and commonly stronger than spiral sculpture. Axial ribs narrow to moderately wide in size and spacing; straight or curved, commonly elongate and extending from suture to suture, but not aligned with axial ribs on adjacent whorls. Axial ribs can be noded. Axial ribs common on spire and most of last whorl; or axial ribs only on upper spire. Spiral ribs very weak to strong, narrow to moderately wide, commonly closely spaced. Spiral ribs strongest on shoulder and neck but can be nearly obsolete on shoulder of last whorl. Cancellate sculpture moderately common. Aperture narrow to moderately wide, narrowly elongate. No anal sulcus. Outer lip thin and smooth. Columella callus slight, with zero or two to four concealed plaits of variable strength. Siphonal canal commonly long but can be relatively short (attenuated). Siphonal notch narrow to moderately narrow. Anterior end very rarely upturned slightly but untwisted (i.e., no siphonal fasciole). Operculum absent, or very small with subcentral nucleus, or medium sized with terminal nucleus. Growth line straight or inclined on spire whorls; slightly sinuous on last whorl, with deflections near suture, on angulation at periphery, and on neck (Bentson, 1940; Kantor et al. 2001; herein). |
Measurements
No measurements are available
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| Source: o = order, c = class | |||||
| Reference: Kiessling 2004 | |||||
Age range: Late/Upper Campanian or 83.60000 to 72.20000 Ma
Collections: one only
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Late/Upper Campanian | USA (California) | Exilia stechesonae (type locality: 185168) |