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Tannuolina zhangwentangi
Taxonomy
Tannuolina zhangwentangi was named by Qian and Bengtson (1989). It is not extant. Its type locality is Bed Mb13, Meishucun section, which is in a Nangaoian/Atdabanian carbonate siltstone/phosphorite in the Qiongzhusi Formation of China.
Synonymy list
| Year | Name and author |
|---|---|
| 1989 | Tannuolina zhangwentangi Qian and Bengtson p. 82 |
| 2004 | Tannuolina zhangwentangi Li and Xiao figs. 2.1-2.3, 4, 5 |
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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.
†Tannuolina zhangwentangi Qian and Bengtson 1989
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| G. Li and S. Xiao 2004 | Sclerites of Tannuolina zhangwentangi have been described in detail in the literature (Qian and Bengtson, 1989; Conway Morris and Chen, 1990). The Xiaotan population is largely consistent with previous descriptions. Sclerites consist of growth lamellae variably spaced at about 0–60 mm intervals (Fig. 4.12). Mitral sclerites are asymmetrical and have one carina on the interior surface of the carinate side (Fig. 5.10). The carina on the interior surface usually corresponds to a depression on the outer surface. The decrescent side is flat and triangular in shape and it does not expand outwardly as much as the other three sides (Fig. 5.7). Bilateral symmetrical sellate sclerites are triangular, with an apical divergence angle of about 50–80 degrees. Sella may or may not be well developed. There may be a narrow furrow in the middle of the sella (arrows in Fig. 4.4). Duplicature typically adpressed to inner surface of the sella, more so in specimens with a well-developed sella (Fig. 4.5–4.7, 4.10). Duplicature occupies about two-thirds of the length of the sellate sclerite. Pores and canals, about 8–25 mm in diameter, are present on both types of sclerites (including the apical area, Fig. 5.16), but are sparse or absent on the duplicature, sella (if developed), and decrescent sides; growth lines are closely spaced on these sides, too (Fig. 4.11).
In a composite specimen (Fig. 4.1, 4.2), a small sellate (about 0.8 mm in maximum width) lies in the sella of a larger sellate (about 1.5 mm in maximum width). This specimen resembles the composite specimen illustrated by Qian and Bengtson (1989, fig. 55), and can also be interpreted as ontogenetic merging. No sella is developed on the smaller sellate, but a shallow furrow (arrows in Fig. 4.2) suggests that the presumed sella side faces away from the larger sellate. The merging occurs near the apertural margin, indicating the specimen was fossilized shortly after ontogenetic merging. In contrast, the specimen illustrated by Qian and Bengtson (1989) was preserved long after the ontogenetic merging occurred and the smaller sellate was aborted. In another rare composite specimen, two mitral sclerites are opposingly adpressed in left-right symmetry, along the apertural margins of the decrescent sides (Fig. 5.2–5.4). The apices of these two sclerites, however, are separated by a short distance of 0.65 mm. |
Measurements
No measurements are available
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| Source: g = genus, o = order, c = class, p = phylum, uc = unranked clade | |||||
| References: Hendy et al. 2009, Kiessling 2004, Nesnidal et al. 2013, Aberhan et al. 2004, Hendy 2009 | |||||
Age range: base of the Meishucunian to the top of the Atdabanian or 530.70000 to 516.00000 Ma
Collections (11 total)
| Time interval | Ma | Country or state | Original ID and collection number |
|---|---|---|---|
| Meishucunian | China (Yunnan) | Tannuolina zhangwentangi (96290 96291 96292 96296) | |
| Meishucunian - Tommotian | China (Yunnan) | Tannuolina zhangwentangi (96301 96302) | |
| Atdabanian | China (Shaanxi) | Tannuolina zhangwentangi (8091) | |
| Atdabanian | China (Yunnan) | Tannuolina zhangwentangi (86691) | |
| Atdabanian | China | Tannuolina zhangwentangi (8331 8333) | |
| Nangaoian - Atdabanian | China (Yunnan) | Tannuolina zhangwentangi (type locality: 96446) |