File:Tentaculite in Devonian limestone (48873661118).jpg
Original file (1,871 × 1,006 pixels, file size: 1.86 MB, MIME type: image/jpeg)
Captions
Captions
Summary
[edit].jpg&action=edit§ion=1){kind=link}
| Description |
Tentaculites are problematic fossils - their high-level taxonomic placement is uncertain, but they may be molluscs. Tentaculite fossils consist of small to very small calcitic shells. The shells are straight to slightly curving and are slightly tapering tubes. The pointed end of the shell is closed. In some forms, the pointed end is slightly bulbous, with an apical spine (usually broken off). Externally, tentaculite shells usually have ringed ornament and thin, delicate, longitudinal striations. The tip of the shell is the embryonic part. After that is the juvenile portion of the shell, which consists of internal septa, or walls that divide the shell into chambers. Septa have no external expression and number 5 to 20 in one specimen. The adult portion of the shell is nonseptate - it is referred to as the living chamber, which occupies more than half the entire length of the shell. No aperture-like structure has ever been found at the distal end of the shell. The soft-part morphology of tentaculites is poorly known. X-ray images of specimens from the Lower Devonian of Germany seem to show multiple "tentacles" protruding from the large end of the shell. Muscle impressions on the interior have been reported in some tentaculites. Tentaculites are entirely extinct - their geologic range depends on how inclusive the term "tentaculite" is. Tentaculites first definitely appear in Ordovician rocks. Their maximum abundance and diversity was during the Devonian. Tentaculites were entirely marine. They are known from shallow and deep-water deposits. Larger, thick-shelled forms are local in their distribution, and so appear to have been benthic. Smaller, thin-shelled forms have world-wide distributions, and so appear to have been planktonic. Planktonic forms, such as the styliolinids, may not be tentaculites at all. Sometimes, encrusters are found on tentaculite shells. The distribution of encrusting organisms suggests that benthic tentaculites had the apex of the shell pointed downward and the aperture was upward during life. Almost all tentaculite fossils are found parallel to bedding. Very few have been found with the pointed end of the shell vertically inserted into the sediments. Classification: Animalia incertae sedis, Tentaculita, Tentaculitida, Tentaculitidae Locality: building stone at Marion Depot, Marion, Ohio, USA |
| Date | |
| Source | Tentaculite in Devonian limestone |
| Author | James St. John |
Licensing
[edit].jpg&action=edit§ion=2){kind=link}
- You are free:
- to share – to copy, distribute and transmit the work
- to remix – to adapt the work
- Under the following conditions:
- attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
|
This image was originally posted to Flickr by James St. John at https://flickr.com/photos/47445767@N05/48873661118 (archive). It was reviewed on 7 December 2019 by FlickreviewR 2 and was confirmed to be licensed under the terms of the cc-by-2.0. |
File history
Click on a date/time to view the file as it appeared at that time.
| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 19:10, 7 December 2019 | | 1,871 × 1,006 (1.86 MB) | Ser Amantio di Nicolao (talk | contribs) | Transferred from Flickr via #flickr2commons |
You cannot overwrite this file.
File usage on Commons
The following page uses this file:
File usage on other wikis
The following other wikis use this file:
- Usage on ia.wikipedia.org
- Usage on www.wikidata.org
- Usage on zh.wikipedia.org
.jpg&oldid=890734437){kind=link}