IHN 1005, Veinte de Noviembre (Eocene of Mexico)

Where: Chiapas, Mexico (16.6° N, 92.9° W: paleocoordinates 18.4° N, 83.6° W)

• coordinate estimated from map

• outcrop-level geographic resolution

When: San Juan Formation, Lutetian (47.8 - 41.3 Ma)

• STRATIGRAPHIC RELATIONS: Assigned to the San Juan Formation in Vega et al. 2001, but reassigned to the El Bosque Formation by Perrilliat et al. (2006) on age, but not lithology. Formations are defined lithologically, not chronologically, so even if the early Eocene age is correct, it still belongs to the San Juan Formation. THICKNESS: From individual bed within section of 40 m thickness. Thickness of formation in this region is 200 m, but ranges from between 720 and 2000 m. AGE: 2). Presence of the foraminiferans Lepidocyclina (Polylepidina) antillea, Storrsella haastersi, Sigmoilopsis centralamericana, Nummulites (Paleonummulites) panamensis, and Pellatispirella matleyi suggest a middle Eocene age for the sediments of this locality. Later assigned to Ypresian on the basis of Sr isotope dating of nautilid Hercoglossa, which yields an age of ~52 Ma. The foraminiferal and lithostratigraphic context suggests the original middle Eocene age is more likely. STRATIGRAPHIC POSITION: From near top of section, within "Grit Mbr" (apparently informal) of the lower El Bosque Fm.

• bed-level stratigraphic resolution

Environment/lithology: open shallow subtidal; lithified, shelly/skeletal, yellow limestone

• ENVIRONMENT: "Open marine shallow shelf paleoenvironment" in Perrilliat et al. (2006). Ferrusquía-Villafranca et al. (2000) defined six lithofacies and assigned a shallow marine platform, located not far from the littoral zone.
• SPECIFIC LITHOLOGY: Yellowish brown fine-grained calcarenite, according to Perilliat (2003). LITHIFICATION: Lithified, on the basis of figured specimens and facies description.

Size class: macrofossils

Preservation: cast, mold/impression

Collection methods: COLLECTOR: Not stated, but possibly including M. C. Perilliat and colleagures. REPOSITORY: Instituto de Geologia, UNAM, Ciudad Universitaria, Mexico (IGM).

Primary reference: M. D. Perrilliat, J. Avendano, F. J. Vega and J. Solé. 2006. Lower Eocene Gastropods from El Bosque Formation, Central Chiapas, Mexico. The Veliger 48(3):151-169 [A. Hendy/A. Hendy/M. Uhen]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 79943: authorized by Austin Hendy, entered by Austin Hendy on 27.03.2008, edited by Pete Wagner

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Not exhaustive, limted to gastropoda and other taxa mentioned in text. "The diversity of marine organisms is remarkable" apparently. NOMENCLATURE: Authoritative publication with modern nomenclature and use of species and subgenus rank.
Cephalopoda
 Nautilida - Hercoglossidae
Hercoglossa cf. ulrichi White 1882 nautiloid
Gastropoda
 Trochoidea - Trochidae
Calliostoma granulata Perrilliat et al. 2006 top snail
Trochus sp. Linnaeus 1758 top snail
 Epitonioidea - Epitoniidae
Cirsotrema sp. Mörch 1852 wentletrap
 Neotaenioglossa - Calyptraeidae
"Calyptraea aperta" = Calyptraea (Trochita) aperta
"Calyptraea aperta" = Calyptraea (Trochita) aperta Solander 1766 slipper shell
 Cerithioidea - Cerithiidae
"? Iddingsia sp." = Iddingsella Olsson 1944 cerith snail
Bittium (Bittium) estellense cerith snail
originally Bittium (Bittium) estellensis, Palmer and Brann updated to Bittium (Bittium) estellense
"Cerithium" sp. Bruguière 1789 cerith snail
 Cerithioidea - Turritellidae
Mesalia alabamiensis De Gregorio 1890 turret shell
"Palmerella mortoni" = Kapalmerella mortoni Conrad 1830 turret shell
SUBSPECIES: Palmerella mortoni mexicana
? Palmerella sp. Allmon 1996 turret shell
"Turritella" sp. Lamarck 1799 turret shell
"Turritella" humerosa Conrad 1835 turret shell
SUBSPECIES: "Turritella" humerosa sanjuanensis
 Cerithioidea - Potamididae
 Architaenioglossa - Ampullinidae
Pachycrommium clarki Stewart 1927 snail
 Sorbeoconcha - Seraphsidae
Terebelum (Seraphs) sp. Montfort 1810 snail
 Neogastropoda - Melongenidae
Levifusus sp. Conrad 1865 snail
? Cornulina sp. Conrad 1853 snail
 Neogastropoda - Clavatulidae
Turricula sp. Schumacher 1817 snail
 Neogastropoda - Pseudolividae
Sulcobuccinum cf. scalina Heilprin 1880 snail
 Neogastropoda - Ptychatractidae
Exilia sp. Conrad 1860 snail
 Neogastropoda - Volutidae
Volutilithes cf. muricinus Lamarck 1802 volute
Lapparia cf. nuda Stenzel and Turner 1940 volute
Lyrischapa spinifera Perrilliat et al. 2006 volute
Volutocorbis minutus Perrilliat et al. 2006 volute
Athleta petrosa Conrad 1833 volute
SUBSPECIES: Athleta petrosa petrosa
 Sorbeoconcha - Cassidae
Galeodea koureos Gardner 1939 snail
 Sorbeoconcha - Eocypraeidae
"Eocypraea (Eocypraea) inflata" = Eocypraea inflata Lamarck 1802 snail
Eocypraea (Eocypraea) sp. Cossmann 1903 snail
 Sorbeoconcha - Cypraeidae
Bernaya (Bernaya) media Deshayes 1835 cowry
Bernaya (Bernaya) media chiapasensis
Bernaya (Bernaya) obesa Deshayes 1866 cowry
Cypraeorbis sp. Conrad 1865 cowry
Cypraeorbis alabamensis de Gregorio 1890 cowry
Cypraeorbis alabamensis ventripotens; Cypraeorbis alabamensis mexicana
"Proadusta subrostrata" = Eopustularia subrostrata Gray 1824 cowry
Proadusta subrostrata bartonensis
"Proadusta acyensis" = Eopustularia acyensis Raincourt 1876 cowry
"Bernaya (Protocypraea) cf. angystoma" = Lyncina amygdalina Deshayes 1835 cowry
Macrocypraea veintensis n. sp. Perrilliat et al. 2003 cowry
Proadusta sp. Sacco 1894 cowry
 Sorbeoconcha - Naticidae
Crommium globosa Perrilliat et al. 2006 moon snail
 Heterostropha - Acteonidae
Tornatellaea bella Conrad 1860 snail
 Heterostropha - Architectonicidae
Architectonica sp. Röding 1798 sundial
Architectonica alabamensis Dall 1892 sundial