Alexandrium spp.
Alexandrium is a genus of dinoflagellates. It contains some of the dinoflagellate species most harmful to humans, because it produces toxic harmful algal blooms (HAB) that cause paralytic shellfish poisoning (PSP) in humans. There are about 30 species of Alexandrium that form a clade, defined primarily on morphological characters in their thecal plates.

Philippe Garcelon · CC BY 2.0 · 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 most 7.1 million years on record.
The one occurrence read is dated to somewhere between 48.07 Mya and 41.03 Mya, which is a dating window rather than a span.
1 occurrence of Alexandrium spp. on record, most of them in the Eocene. 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
1 occurrences- Eocene100%
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
Loading coastlines…
The named rock units Alexandrium spp. has been recovered from, largest first. Drawn where the rock is now, not where it formed.
Alexandrium spp. and its relatives
EoceneWhere Alexandrium spp. and its relatives were recorded in the Eocene.
Found in the same rock
7 taxa- Areoligera1 site
- Chiropteridium1 site
- Cooksonidium capricornum1 site
- Dracodinium1 site
- Glaphyrocysta1 site
- Hemisphaeridium fenestratum1 site
- Rhombodinium1 site
The Paleobiology Database records 1 site for Alexandrium spp., and this reads all of them. The number is how many of those sites it was catalogued from too.
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
1 referenceEach of the 1 occurrence 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. Each entry links to doi.org. Relayed as the Paleobiology Database holds them, not checked against what they resolve to.
Media and terms
Media content1
Picture of Alexandrium spp.
- Source
- Wikipedia/Commons
- Credit
- Philippe Garcelon
- Licence
- CC BY 2.0
- Commercial use
- the licence allows it
No 3D scan of Alexandrium spp. 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 itFormations of the EoceneThe world it lived on
Occurrence data from the Paleobiology Database, CC BY 4.0.