Abra
Abra is a genus of saltwater clams, marine bivalve mollusks in the family Semelidae. Members of this genus are mostly under 1.5 centimeters long, and have thin shells which are usually white. These bivalves normally live under the surface of sandy and muddy sediments, in the neritic zone.

Jan Johan ter Poorten · CC BY-SA 3.0 · via Wikipedia/Commons. May be a photograph of a specimen, or an artist’s reconstruction — an interpretation of a skeleton, since colour and soft tissue are almost never preserved.
On record
Recorded, not inferred- Also called
- abraPBDB
- Sits inside
- SemelidaePBDB
- Diet
- deposit feeder, suspension feederPBDB
- Life habit
- infaunalPBDB
- Motility
- facultatively mobilePBDB
- Vision
- blindPBDB, for Bivalvia
Time the record covers
At least 48 million years on record.
The record covers at least 48.07 Mya to 11.7 ka. No occurrence read is dated outside 56 Mya to 0 Mya.
347 occurrences of Abra on record, most of them in the Pleistocene. The Paleobiology Database records this as a living group. Bar height is expected occurrences, not a count: each fossil is spread across the span it is dated to, so a tall narrow bar means tight dating and a low wide one means loose.
When
347 occurrencesThese are dates about fossils, not the animal: the record can only begin after it arose and end before it died out, so either end may reach further. Shares are expected occurrences: a fossil dated to a span is counted partly in each period it straddles. More on what this infers.
Found in
80 formations
- Cook Mountain Formation · Claiborne Group22
- Moodys Branch Formation · Jackson Group17
- Falun de Jeurs Formation12
- Morne l'Enfer Formation11
- Bowden Formation · Coastal Group8
- Norwich Crag Formation · Crag Group8
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The named rock units Abra has been recovered from, largest first. Drawn where the rock is now, not where it formed. 56 further formations hold fewer occurrences each and are not listed. 79 occurrences have no formation on record, which is common for older literature.
Abra and its relatives
PleistoceneWhere Abra and its relatives were recorded in the Pleistocene.
Found in the same rock
2,705 taxa- Turritella49 sites
- Varicorbula gibba39 sites
- Naticidae38 sites
- Parvicardium36 sites
- Odostomia31 sites
- Cyclocardia29 sites
- Cadulus28 sites
- Mitrella28 sites
- Gastropoda27 sites
- Euspira26 sites
- Nassarius26 sites
- Elphidium25 sites
- Limopsis25 sites
- Yoldia (Yoldia) glaberrima25 sites
- Aporrhais (Aporrhais)24 sites
- Astarte (Astarte) radiata24 sites
- Dentalina24 sites
- Lentigodentalium24 sites
- Limopsis (Limopsis) aurita24 sites
- Lunulites24 sites
- Reussirella24 sites
- Saccella westendorpi24 sites
- Spiroplectammina carinata24 sites
- Venus (Ventricoloidea) multilamella24 sites
The Paleobiology Database records 236 sites for Abra, and this reads all of them. Of that, one read hit the database's own return limit, so every count below is a floor rather than a total. The number is how many of those sites it was catalogued from too. The 24 sharing the most are listed.
This is not a list of everything alive at the time. It is only what has come out of the same ground as this animal and been written down.
Entered from
90 references- Die Fauna des marinen Miozäns von Kevelaer (Niederrhein). Band 2 Bivalvia, Scaphopoda, Cephalopoda, Bryozoa, Annelida, Brachiopoda34
- Biostratigraphie et paleoecologie des gisements types du Stampian de la region d''Etampes (Essonne)29
- Resilience of marine invertebrate communities during the early Cenozoic hyperthermals20
- Marine Molluscan Assemblages in the Early Pleistocene of Sidestrand, Bramerton and the Royal Society Borehole at Ludham, Norfolk20
- Unpublished census data from Atlantic coastal plain and circum-Caribbean Neogene assemblages and taxonomic opinions18
- Fossil assemblages of a marine transgressive sand, Moody''s Branch Formation (Upper Eocene), Louisiana and Mississippi15
- Miocene and Pliocene mollusks from Trinidad11
- Ecological control of evolutionary rates in Paleocene - Eocene marine molluscs9
- Mollusca from the Miocene and Lower Pliocene of Virginia and North Carolina. Part 1. Pelecypoda9
- The Neogene Bivalvia (Heterodonta and Anomalodesmata) and Scaphopoda from Kallo and Doel (Oost Vlaanderen, Belgium)8
- Faunal stability and environmental change in the middle Eocene Gulf Coastal Plain (PhD Thesis, Harvard University)8
- A paleobiotic survey of Caribbean faunas from the Neogene of the Isthmus of Panama7
Each of the 347 occurrences read was entered from one of these publications, ordered by how many each accounts for. This is not a search for papers mentioning the name. 78 further references are not listed. Entries link to doi.org where the Paleobiology Database holds an identifier, and to its own record where it does not. Relayed as the Paleobiology Database holds them, not checked against what they resolve to.
Media and terms
Media content1
Picture of Abra
- Source
- Wikipedia/Commons
- Credit
- Jan Johan ter Poorten
- Licence
- CC BY-SA 3.0
- Commercial use
- the licence allows it
No 3D scan of Abra was found in Sketchfab.
Smithsonian Open Access and MorphoSource were not reached for this taxon, so this list is what the others held rather than everything there is.
The description on this site
- Licence
- CC BY-SA 4.0
This is what the site found, which is not the same as what exists.
Keep going
What may have been alongside itSemelidae through timeFormations of the PleistoceneThe world it lived on
Occurrence data from the Paleobiology Database, CC BY 4.0. Lamarck 1818