Rostroconchia
The Rostroconchia is a class of extinct molluscs dating from the early Cambrian to the Late Permian. They were initially thought to be bivalves, but were later given their own class. They have a single shell in their larval stage, and the adult typically has a single, pseudo-bivalved shell enclosing the mantle and muscular foot. The anterior part of the shell probably pointed downward and had a gap from which the foot could probably emerge. Rostroconchs probably lived a sedentary semi-infaunal lifestyle. There were probably more than 1,000 species of members of this class.

Peter J. Wagner Mithril · Public Domain · 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- Sits inside
- MolluscaPBDB
- Diet
- suspension feederPBDB
- Life habit
- semi-infaunalPBDB
- Motility
- stationaryPBDB
- Vision
- blindPBDB
Time the record covers
At least 261 million years on record.
The record covers at least 516 Mya to 254.14 Mya. No occurrence read is dated outside 538.8 Mya to 251.902 Mya.
939 occurrences of Rostroconchia on record, most of them in the Ordovician. The Paleobiology Database records this as a living group, and the chart stops with its fossils rather than at the present. 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
939 occurrences- Cambrian12%
- Ordovician34%
- Silurian8%
- Devonian14%
- Carboniferous19%
- Permian13%
These 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
346 formations
- Ninmaroo Formation51
- Tomahawk Formation42
- Pacoota Formation27
- Delorme Formation25
- Shakhtau Reef Formation21
- Wan-wan-kou Formation17
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The named rock units Rostroconchia has been recovered from, largest first. Drawn where the rock is now, not where it formed. 322 further formations hold fewer occurrences each and are not listed. 57 occurrences have no formation on record, which is common for older literature.
Rostroconchia and its relatives
OrdovicianWhere Rostroconchia and its relatives were recorded in the Ordovician.
Found in the same rock
3,977 taxa- Conocardium58 sites
- Crinoidea41 sites
- Favosites35 sites
- Gastropoda32 sites
- Bryozoa30 sites
- Fenestella29 sites
- Conocardioidea26 sites
- Atrypa reticularis24 sites
- Nucleospira24 sites
- Rugosa24 sites
- Platyceras23 sites
- Ostracoda22 sites
- Schizophoria22 sites
- Trilobita22 sites
- Cypricardinia21 sites
- Schuchertella20 sites
- Syringopora20 sites
- Bivalvia19 sites
- Cleiothyridina19 sites
- Composita19 sites
- Cornulites19 sites
- Atrypa18 sites
- Camarotoechia18 sites
- Echinoidea18 sites
The Paleobiology Database records 738 sites for Rostroconchia, and this reads 240 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
288 references- Cambrian and Ordovician rostroconch molluscs from Northern Australia129
- The paleontology of rostroconch mollusks and the early history of the phylum Mollusca44
- Paleozoic Gastropod, Rostroconch, Helcionelloid and Tergomyan Database (2006 - 2023)40
- Some silicified Middle Silurian rostroconchs (Mollusca) from the Mackenzie Mountains, N.W.T., Canada19
- Faunal study of the Wanwanian (basal Ordovician) series with special notes on the Ribeiridae and the Ellesmereoceroids18
- The youngest representatives of the genus Ribeiria Sharpe, 1853 from the late Katian of the Prague Basin (Bohemia)17
- The genus Conocardium from Australian Palaeozoic rocks15
- Taxonomical diversity and morphology of rostroconch shells of the family Arceodomidae fam. nov. from the Early Permian Shakhtau reef massif (Mollusca; southern Cis-Urals)14
- Mississippian rostroconch molluscs from Ohio14
- Late Palaeozoic Mollusca and correlations from the south-east Bowen Basin, east Australia14
- Stauffer, 190914
- Structure, taxonomy, and epifauna of Pennsylvanian rostroconchs (Mollusca)12
Each of the 939 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. 276 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 Rostroconchia
- Source
- Wikipedia/Commons
- Credit
- Peter J. Wagner Mithril
- Licence
- Public Domain
- Commercial use
- the licence allows it
No 3D scan of Rostroconchia 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 itMollusca through timeFormations of the OrdovicianThe world it lived on
Occurrence data from the Paleobiology Database, CC BY 4.0. Pojeta et al. 1972