Zygnema

Zygnema is a genus of freshwater filamentous thalloid alga comprising about 100 species. A terrestrial species, Z. terrestre, is known from India. Zygnema grows as a free-floating mass of filaments, although young plants may be found anchored to streambeds with a holdfast. The filaments form a yellow-green to bright green colored tangled mat, and are composed of elongate barrel-shaped cells, each with two star-shaped (stellate) chloroplasts arrayed along the axis of the cell.

A picture published with the record for Zygnema. What it shows has not been checked.

Bob Blaylock · 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.

Time the record covers

At least 10 million years on record.

The record covers at least 33.9 Mya to 23.04 Mya. No occurrence read is dated outside 48.07 Mya to 11.63 Mya.

Eocene — about 1 of 5 occurrencesEoceneOligocene — about 1 of 5 occurrencesOligoceneMiocene — about 3 of 5 occurrencesMiocene49–48 Mya — about 0.0 occurrences48–46 Mya — about 0.1 occurrences46–45 Mya — about 0.1 occurrences45–44 Mya — about 0.1 occurrences44–42 Mya — about 0.1 occurrences42–41 Mya — about 0.1 occurrences41–40 Mya — about 0.1 occurrences40–39 Mya — about 0.1 occurrences39–37 Mya — about 0.1 occurrences37–36 Mya — about 0.1 occurrences36–35 Mya — about 0.1 occurrences35–34 Mya — about 0.1 occurrences27–26 Mya — about 0.2 occurrences26–25 Mya — about 0.2 occurrences25–24 Mya — about 0.2 occurrences24–22 Mya — about 0.3 occurrences22–21 Mya — about 0.4 occurrences21–20 Mya — about 0.4 occurrences20–18 Mya — about 0.4 occurrences18–17 Mya — about 0.4 occurrences17–16 Mya — about 0.4 occurrences16–15 Mya — about 0.4 occurrences15–13 Mya — about 0.4 occurrences13–12 Mya — about 0.4 occurrences12–11 Mya — about 0.2 occurrences33.9 Mya23.04 Mya48.8 Mya10.9 Mya

5 occurrences of Zygnema on record. 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

5 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

2 formations

Cullen — 53.00°S, 68.67°WCullen — 52.87°S, 68.41°WHuitrera — 40.67°S, 71.08°W

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The named rock units Zygnema has been recovered from, largest first. Drawn where the rock is now, not where it formed.

Found in the same rock

79 taxa

The Paleobiology Database records 2 sites for Zygnema, 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

3 references

Each of the 5 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 Zygnema

Credit
Bob Blaylock
Licence
CC BY-SA 3.0
Commercial use
the licence allows it

No 3D scan of Zygnema 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 itThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. Agardh 1817