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Placoolithus
Taxonomy
Placoolithus was named by Zhao (1979) [nomen nudum in this paper; properly named in Zhao and Zhao 1998]. It is considered to be a form taxon. Its type is Placoolithus taohensis.
It was assigned to Spheroolithidae by Zhao (1979), Mikhailov (1994), Mikhailov (1997); and to Dendroolithidae by Zhao and Zhao (1998), Cousin (2002), Liang et al. (2009), Zhang et al. (2018), Chen et al. (2025).
It was assigned to Spheroolithidae by Zhao (1979), Mikhailov (1994), Mikhailov (1997); and to Dendroolithidae by Zhao and Zhao (1998), Cousin (2002), Liang et al. (2009), Zhang et al. (2018), Chen et al. (2025).
Synonyms
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Synonymy list
| Year | Name and author |
|---|---|
| 1979 | Placoolithus Zhao p. 337 |
| 1994 | Placoolithus Mikhailov p. 151 |
| 1997 | Placoolithus Mikhailov p. 44 |
| 1998 | Placoolithus Zhao and Zhao pp. 284, 291 |
| 2002 | Placoolithus Cousin p. 47 |
| 2009 | Placoolithus Liang et al. p. 1591 |
| 2018 | Placoolithus Zhang et al. p. 673 |
| 2025 | Placoolithus Chen et al. |
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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. †Placoolithus Zhao 1979
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†Placoolithus taohensis Zhao and Zhao 1998
†Placoolithus tiantaiensis Jin 2008
†Placoolithus tumiaolingensis Zhou et al. 1998
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Invalid names: Dendroolithus hongzhaiziensis Zhou et al. 1998 [synonym], Paradendroolithus qinglongshanensis Zhou et al. 1998 [synonym]
Invalid names: Paradendroolithus Zhou and Ren [synonym]
Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| H. Zhao and Z. Zhao 1998 | See the diagnosis of Placoolithus taohensis oogen. et oosp. nov. | |
| S. Zhang et al. 2018 | The emended oogenus Placoolithus is characterized by the following unique combination of characters: oblate egg shape; an equatorial plane circular or sub-circular with long axis of 120–170 mm and short axis of 117–159 mm; eggshell thickness of 1.31–2.40 mm. Moreover, symmetric or asymmetric branches of eggshell unit usually appear in themiddle part of the eggshell, and occasionally near the outer surface of the eggshell (Figs. 3A, 4). |