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Quasiaulacera occidua
Taxonomy
Quasiaulacera occidua was named by Copper et al. (2013) [= 1857 “tree-like fossil” Richardson, p. 216.
= 1886? Beatricea nodulosa Billings; Nicholson, pl. 8, figs. 6, 7.
= 1982 “aulacerid” Petryk, 1982, pl. 1, figs. 1–3, pl. 2, fig. 1.
= 1994 “New aulacerid genus” Cameron and Copper, fig. 2b, 2d.
= 1998 “Quasiaulacera” (idealized reconstruction); Desrochers et al., fig. 3.
= 2011 “Quasiaulacera sp. B” Copper, Nestor, and Stock, fig. 1A, 1D, 1E.]. Its type specimen is GSC 129346 and is a 3D body fossil. Its type locality is A0972 Laframboise Creek, Anticosti Island, which is in a Hirnantian shallow subtidal limestone in the Ellis Bay Formation of Canada. It is the type species of Quasiaulacera.
Synonymy list
| Year | Name and author |
|---|---|
| 2013 | Quasiaulacera occidua Copper et al. pp. 671 - 672 figs. 3.3–3.6, 6, 7 |
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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.
†Quasiaulacera occidua Copper et al. 2013
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| P. Copper et al. 2013 | Quasiaulacera with relatively thick outer laminar layer of 10–20 concentric, closely spaced laminae penetrated by continuous, superposed pillars up to ∼10 mm long, 0.2–0.3 mm in diameter, protruding through successive outer laminae, and thicker at base of each lamina than at top. Pillars begin at base of outer laminar layer, but absent in intermediate microcyst-plate layer. Large, smooth-sided axial cavity filled with stack of single large cyst-plates. This is surrounded by middle layer of microcyst-plates, outer parts of which form grooves and ridges reflected in outer laminar envelope as fluting.
Long, continuous single columnar skeletons may be up to or exceed 2 m in length, with diameters in the range of 15–20 cm, and are longitudinally grooved on the outside; basal diameters of mature specimens measured in situ on the bedding plane average ∼20 cm in diameter (Fig. 3.5, 3.6). Specimens are commonly broken or crushed in the recumbent position, as the large hollow axial cavity, usually missing the central cyst-plates due to bioerosion or dissolution, led to fractures. Outer surface of well preserved specimens are minutely pustulose, due to the pillars in the outer laminae evident on the surface. Outer laminar layer consists of 10–20 distinctive laminae, cumulatively 1–3 cm thick, penetrated by numerous long, non-branching pillars over 10–12 mm (Figs. 6, 7) in extent, and 0.3 mm in diameter, evenly but irregularly spaced at 0.5 to 1.0 mm (Fig. 7.1–7.4). New pillars are inserted between older pillars with skeletal expansion (Fig. 6.2, 6.3). The laminae are more densely packed in the grooves (4 per mm) than in the ridges, where they are spaced at about 3 per mm (see Fig. 6.2). Middle layer (Fig. 6.1, 6.3) composed of small microcyst-plates up to ∼0.5 mm in diameter and 0.2–0.3 mm high; this layer may occupy 30–40 percent of the skeleton overall; wave-like expansion of the outer part of the middle layer, and expanded through variations in the spacing of the laminar layers, led to the fluted external skeletal form. The large axial cavity makes up about 40–50 percent of the skeleton, but cyst-plates are almost never preserved here, and thus their nature is obscure; where preserved, fragments of cyst-plates are extremely thin. |
Measurements
No measurements are available
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| Source: o = order | |||||
| Reference: Kiessling 2004 | |||||
Age range: Hirnantian or 445.20000 to 443.40000 Ma
Collections: one only
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Hirnantian | Canada (Quebec) | Quasiaulacera occidua (type locality: 113323) |