"Microfossil" bed - Ambatolafia, Mahajanga Basin, Madagascar (Cretaceous of Madagascar)

Where: Mahajanga, Madagascar (16.5° S, 46.2° E: paleocoordinates 40.5° S, 29.6° E)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Microfossil Bed Member, Early/Lower Albian (112.0 - 109.0 Ma)

• From Microfossil bed. Ammonites collected from a sandstone layer ("ammonite bed"), which is 15-20 cm thick. Above this unit is a 15 cm thick bed of siltstone ("microfossil bed", with sparse gastropods and bivalves. Overlain by further barren siltstone of 10 cm thickness. The fauna belongs to the Cleoniceras besairiei Zone of the lower Albian (Collignon, 1963).

• bed-level stratigraphic resolution

Environment/lithology: coastal; poorly lithified, glauconitic, gray siltstone

• No specific environmental or geologic data reported by authors.
• Dark gray, glauconite siltstone.

Size class: macrofossils

Reposited in the MfN

Collection methods: bulk, sieve,

• The material is deposited in the Museum für Naturkunde, Berlin, Germany. This is a recollection of a locality originally reported by Collignon (1949), based on collections by H. Besairie and V. Hourcq. This locality fell into oblivion until rediscovered by French-Madagascar ammonite traders a few years ago, who had relocated the the locality. Processed using a 5-10% H2O solution using standard procedures, then washed through sieves with mesh sizes of 2, 1, 0.5, 0.2, and 0.064 mm. Gastropods only picked from the 2, 1 and 0.5 mm fractions.

Primary reference: S. Kiel. 2006. New and little-known gastropods from the Albian of the Mahajanga Basin, northwestern Madagascar. Journal of Paleontology 80(3):455-476 [A. Miller/A. Hendy]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 60072: authorized by Austin Hendy, entered by Austin Hendy on 29.04.2006

Creative Commons license: CC BY (attribution)

Taxonomic list

• Exhaustive for gastropoda. Bivalves and ammonites are excluded from this publication. These are presumably listed by Collignon (1949).
unclassified
  -
Gastropoda
 Murchisoniina - Zygopleuridae
 Vetigastropoda - Crosseolidae
Conjectura minuta Kiel 2006 snail
 Ptenoglossa -
 Epitonioidea - Nystiellidae
 Cerithioidea - Metacerithiidae
Metacerithium aff. trimoline snail
> 300 specimens
 Cerithioidea - Cryptaulacidae
Cirsocerithium collignoni snail
> 300 specimens
 Sorbeoconcha - Aporrhaidae
Tessarolax retusa Sowerby 1836 snail
 Neogastropoda - Paladmetidae
 Sorbeoconcha - Rissoidae
Buvignieria berwaldi Kiel 2006 snail
> 200 specimens
 Sorbeoconcha - Newtoniellidae
? Vatopsis sp. Gründel 1980 snail
 Sorbeoconcha - Elachisinidae
Entomope crassilabrum Kiel 2006 snail
 Cocculinoidea - Cocculinidae
Cocculina sensu lato sp. Dall 1882 snail
 Heterostropha - Cornirostridae
Tomura ambatolafiensis Kiel 2006 snail
 Heterostropha - Acteonidae
"Actaeon sp." = Acteon
"Actaeon sp." = Acteon Montfort 1810 snail
 Heterostropha - Ringiculidae
 Heterostropha - Mathildidae
? Mathildidae indet. Dall 1889 snail
Juvenile mathildid? [originally entered as "? Mathilididae sp."]
"Carinathilda cf. microstriata" = Angulathilda microstriata Schroder 1995 snail
Carinathilda bandeli Kiel 2006 snail
 Heterostropha - Ampezzanildidae
Ampezzanildidae indet. Bandel 1995 snail
Ampezzanildid larval shell