Syntomodrillia obsoleta

Syntomodrillia obsoleta Temporal range: middle Miocene PreꞒ Ꞓ O S D C P T J K Pg N ↓
Holotype from Auckland War Memorial Museum
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Gastropoda
Subclass:	Caenogastropoda
Order:	Neogastropoda
Family:	Drilliidae
Genus:	Syntomodrillia
Species:	†S. obsoleta
Binomial name
†Syntomodrillia obsoleta Powell, 1944

Syntomodrillia obsoleta is an extinct species of sea snail, a marine gastropod mollusc in the family Drilliidae. ^[1] Fossils of the species date to the middle Miocene, and have been found in the strata of the Port Phillip Basin of Victoria, Australia.

Description

Reverse view of holotype

In the original description, Powell described the species as follows:

Much smaller than sandleroides , has weaker axials and obsolescent spirals. Shell small, glossy ; whorls 5½, including typical smooth, globular protoconch of two whorls. Post-nuclear whorls sculptured with moderately strong, but narrow, obliquely flexuous axials, which extend from the upper suture and fade out about the middle of the base; 12-13 per whorl; 12 on penultimate in holotype. The axials are slightly thickened at the weak peripheral angle, which is just above the middle. There is no spiral sculpture apart from four obsolescent threads on the anterior end. ^[2]

The holotype of the species measures 5.3 mm (0.21 in) in height and 1.9 mm (0.075 in) in diameter. ^[2]

Taxonomy

The species was first described by A.W.B. Powell in 1944. ^[2] The holotype was collected from Fossil Beach, Balcombe Bay, Victoria, Australia, at an unknown date prior to 1944, and is held by the Auckland War Memorial Museum. ^{[3] [4]}

Distribution

This extinct marine species dates to the middle Miocene, and occurs in the strata of the Port Phillip Basin of Victoria, Australia, found in the Gellibrand Formation. ^{[3] [5]}

References

1. Syntomodrillia ludbrookae A. W. B. Powell, 1944 † . 13 November 2025. Retrieved through: World Register of Marine Species .
2. Powell, A. W. B. (1944). "The Australian Tertiary Mollusca of the Family Turridae". Records of the Auckland Institute and Museum . 3: 3–68. ISSN   0067-0464. JSTOR   42905993. Wikidata   Q58676624.
3. Blom, Wilma M. (2025). "Annotated Catalogue of Fossil and Extant Molluscan Types in the Auckland War Memorial Museum". Bulletin of the Auckland Museum . 22. doi:10.32912/BULLETIN/22. ISSN   1176-3213. Wikidata   Q135397912.
4. "Syntomodrillia obsoleta". Collections Online. Auckland War Memorial Museum . Retrieved 13 November 2025.
5. Darragh, Thomas A. (August 2024). "A checklist of Australian marine Cenozoic Mollusca". Memoirs of Museum Victoria . 83: 37–206. doi:10.24199/J.MMV.2024.83.02. ISSN   1447-2546. Wikidata   Q136396722.