Bdelloidea

Bdelloidea is a class of rotifers found in freshwater habitats all over the world. There are over 450 described species of bdelloid rotifers, distinguished from each other mainly on the basis of morphology. The main characteristics that distinguish bdelloids from related groups of rotifers are exclusively parthenogenetic reproduction and the ability to survive in dry, harsh environments by entering a state of desiccation-induced dormancy (anhydrobiosis) at any life stage. They are often referred to as "ancient asexuals" due to their unique asexual history that spans back to over 25 million years ago through fossil evidence. Bdelloid rotifers are microscopic organisms, typically between 150 and 700 μm in length. Most are slightly too small to be seen with the naked eye, but appear as tiny white dots through even a weak hand lens, especially in bright light. In June 2021, biologists reported the restoration of bdelloid rotifers after being frozen for 24,000 years in the Siberian permafrost.

Bdelloidea

Diego Fontaneto · CC BY 2.5 · 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
EurotatoriaPBDB

Time the record covers

At least 51 million years on record.

The record covers at least 72.2 Mya to 20.45 Mya. No occurrence read is dated outside 83.6 Mya to 13.82 Mya.

Late Cretaceous — about 1 of 4 occurrencesLate CretaceousPaleocene — about 0 of 4 occurrencesEocene — about 1 of 4 occurrencesEoceneOligocene — about 0 of 4 occurrencesMiocene — about 2 of 4 occurrencesMiocene85–83 Mya — about 0.1 occurrences83–80 Mya — about 0.2 occurrences80–78 Mya — about 0.2 occurrences78–75 Mya — about 0.2 occurrences75–73 Mya — about 0.2 occurrences73–70 Mya — about 0.1 occurrences39–37 Mya — about 0.3 occurrences37–34 Mya — about 0.6 occurrences34–32 Mya — about 0.1 occurrences22–20 Mya — about 0.2 occurrences20–17 Mya — about 0.7 occurrences17–15 Mya — about 0.7 occurrences15–12 Mya — about 0.3 occurrences72.2 Mya20.45 Mya85 Mya12 Mya

4 occurrences of Bdelloidea on record, most of them in the Miocene. 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

4 occurrences

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

1 formation

La Toca — 19.55°N, 70.61°W

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The named rock units Bdelloidea has been recovered from, largest first. Drawn where the rock is now, not where it formed. 2 occurrences have no formation on record, which is common for older literature.

Bdelloidea and its relatives

Miocene

Where Bdelloidea and its relatives were recorded in the Miocene.

Found in the same rock

466 taxa

The Paleobiology Database records 3 sites for Bdelloidea, and this reads all of them. 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

4 references

Each of the 4 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. 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 Bdelloidea

Credit
Diego Fontaneto
Licence
CC BY 2.5
Commercial use
the licence allows it

No 3D scan of Bdelloidea was found in MorphoSource and Sketchfab.

Smithsonian Open Access was 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 itEurotatoria through timeFormations of the MioceneThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. Hudson 1884