Norrisia norrisii
The marine snail Norrisia norrisii is a medium-sized gastropod mollusk within the family Tegulidae. It has several common names, including Norris's top snail, Norris's topsnail, norrissnail, smooth brown turban snail, or kelp snail. It was first described by G.B. Sowerby I under the name Trochiscus norrisii. It is the only species in the genus Norrisia.

Ed Bierman · 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.
On record
Recorded, not inferred- Also called
- Norris's top-shellPBDB
- Sits inside
- NorrisiaPBDB
- Diet
- grazerPBDB, for Trochoidea
- Life habit
- epifaunalPBDB, for Trochoidea
- Motility
- actively mobilePBDB, for Trochoidea
- Vision
- limitedPBDB, for Gastropoda
Time the record covers
At least 2.4 million years on record.
The record covers at least 2.58 Mya to 129 ka. No occurrence read is dated outside 11.63 Mya to 0 Mya.
44 occurrences of Norrisia norrisii on record, most of them in the Pleistocene. The Paleobiology Database records this as a living group. 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
44 occurrences- Miocene2%
- Plioceneunder 1%
- Pleistocene98%
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
7 formations
- Discovery Point Formation10
- Palos Verdes Sand Formation5
- Quaternary terrace Formation2
- Lomita Marl Formation2
- Unnamed Formation1
- Palos Verdes Formation1
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The named rock units Norrisia norrisii has been recovered from, largest first. Drawn where the rock is now, not where it formed. 22 occurrences have no formation on record, which is common for older literature.
Norrisia norrisii and its relatives
PleistoceneWhere Norrisia norrisii and its relatives were recorded in the Pleistocene.
Found in the same rock
931 taxa- Fissurella volcano31 sites
- Californiconus californicus30 sites
- Callianax biplicata24 sites
- Epilucina californica24 sites
- Lottia limatula22 sites
- Thylacodes squamigerus22 sites
- Lottia scabra21 sites
- Megastraea undosa20 sites
- Chlorostoma funebrale19 sites
- Glans carpenteri19 sites
- Homalopoma (Homalopoma) luridum18 sites
- Lottia insessa18 sites
- Crepipatella lingulata17 sites
- Littorina (Littorina) scutulata17 sites
- Mexacanthina lugubris17 sites
- Amphissa versicolor16 sites
- Chama exogyra16 sites
- Crossata ventricosa16 sites
- Hipponix tumens16 sites
- Leukoma staminea16 sites
- Littorina (Neritrema) keenae16 sites
- Caesia fossatus15 sites
- Calliostoma canaliculatum15 sites
- Chlorostoma gallina15 sites
The Paleobiology Database records 39 sites for Norrisia norrisii, 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
21 references- Invertebrate megafossils of Pleistocene (Sangamon Interglacial) age from Isla de Guadalupe, Baja California, Mexico11
- Paleontology of the Pleistocene of Point Loma, San Diego County, California7
- Late Pleistocene faunas from the northwestern coast of Baja California, Mexico4
- Late Pleistocene molluscan faunas from upper terraces of the Palos Verdes Hills, California3
- Habitats and Sources of Pleistocene Mollusks at Torrey Pines Park, California2
- Late Pleistocene invertebrates of the Newport Bay area, California2
- Paleoecologic analysis and age of a late Pleistocene fossil assemblage from Upper Newport Bay, Newport Beach, Orange County, California1
- A Neogene section northeastern San Clemente Island, California1
- Pleistocene invertebrates from the Dume Terrace, western Santa Monica Mountains, California1
- Geology of San Nicolas Island, California1
- Geology of southeastern Ventura basin, Los Angeles County, California1
- Paleoecologic molluscan geography of the Californian Pleistocene1
Each of the 44 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. 9 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 Norrisia norrisii
- Source
- Wikipedia/Commons
- Credit
- Ed Bierman
- Licence
- CC BY 2.0
- Commercial use
- the licence allows it
No 3D scan of Norrisia norrisii 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 itNorrisia through timeFormations of the PleistoceneThe world it lived on
Occurrence data from the Paleobiology Database, CC BY 4.0. (Sowerby I 1838)