Hexanchus nakamurai

The bigeyed sixgill shark is a cow shark of the family Hexanchidae. Its dorsal surface has a brownish-gray color, and is sharply separated from the light coloring of its ventral surface. The eyes are a fluorescent green while the shark is alive. The body of this shark is small, slim, and fusiform in shape. As the name suggests, this shark has six gill slits, unusual among most shark species. The head is narrow and somewhat flattened, and the mouth contains 5 rows of large, comb-shaped teeth. This shark's single dorsal fin is pushed back towards the caudal fin, and is behind the pelvic fins. The upper caudal fin is much longer than the lower, with a deep notch near the tip. All fins have thin white margins on the edge. In juveniles, the upper caudal fin has a black tip.

Hexanchus nakamurai

Haplochromis · CC0 · 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
bigeyed sixgill sharkPBDB
Sits inside
HexanchusPBDB
Diet
carnivorePBDB, for Hexanchiformes
Life habit
nektonicPBDB, for Hexanchiformes
Motility
actively mobilePBDB, for Hexanchiformes

Time the record covers

At most 2.2 million years on record.

Every occurrence read is dated to somewhere between 13.82 Mya and 11.63 Mya, and nothing in the dating separates them, so that window is what the record shows rather than a span.

Miocene — about 2 of 2 occurrencesMiocene14–14 Mya — about 0.0 occurrences14–14 Mya — about 0.1 occurrences14–14 Mya — about 0.1 occurrences14–13 Mya — about 0.1 occurrences13–13 Mya — about 0.1 occurrences13–13 Mya — about 0.1 occurrences13–13 Mya — about 0.1 occurrences13–13 Mya — about 0.1 occurrences13–13 Mya — about 0.1 occurrences13–13 Mya — about 0.1 occurrences13–13 Mya — about 0.1 occurrences13–13 Mya — about 0.1 occurrences13–13 Mya — about 0.1 occurrences13–12 Mya — about 0.1 occurrences12–12 Mya — about 0.1 occurrences12–12 Mya — about 0.1 occurrences12–12 Mya — about 0.1 occurrences12–12 Mya — about 0.1 occurrences12–12 Mya — about 0.1 occurrences12–12 Mya — about 0.1 occurrences12–12 Mya — about 0.1 occurrences12–12 Mya — about 0.0 occurrences14.32 Mya11.13 Mya

2 occurrences of Hexanchus nakamurai 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

2 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.

Hexanchus nakamurai and its relatives

Miocene

Where Hexanchus nakamurai and its relatives were recorded in the Miocene.

Found in the same rock

29 taxa

The Paleobiology Database records 2 sites for Hexanchus nakamurai, 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

1 reference

Each of the 2 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. Each entry links to the Paleobiology Database's own record for the work.

Media and terms

Media content1

Picture of Hexanchus nakamurai

Credit
Haplochromis
Licence
CC0
Commercial use
the licence allows it

No 3D scan of Hexanchus nakamurai 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 itHexanchus through timeFormations of the MioceneThe world it lived on

Occurrence data from the Paleobiology Database, CC BY 4.0. (Teng 1962)