Súa Memvber, Onzole Formation (Pliocene of Ecuador)

Where: Esmeraldas, Ecuador (0.9° N, 79.9° W: paleocoordinates 0.7° N, 79.1° W)

• coordinate estimated from map

• local area-level geographic resolution

When: Onzole Formation (Daule Group), Early/Lower Pliocene (5.3 - 3.6 Ma)

• LITHOSTRATIGRAPHY: From the Súa Member of the Onzole Fm of the Daule Group, which overlies the lower member of the Onzole Fm (Late Miocene) and the Angostura Fm (Late Miocewne). AGE: Early Pliocene in text. STRATIGRAPHIC POSITION: Composite list 50–70-cm-thick shellbed at the base of the Su ́a Member.

• bed-level stratigraphic resolution

Environment/lithology: coastal; burrowed, bioturbated, silty sandstone

• lthough composed of largely autochthonous-parautochthonous specimens, the fossil assemblage contains mollusk species from a range of water depths and both soft- and hard-bottom habitats, implying in situ time averaging and admixture of different assemblages as transgression proceeded on a sediment-starved shoreline. Known depth ranges of the majority of the extant species, among which A. reinharti and O. splendidula are the dominant elements, point to deposition within an upper shoreface environment, even though a very few taxa, such as Chama pellucida and Ostrea iridescens, inhabit the foreshore zone; however, their presence in the assemblage may be interpreted as related to the substrate requirements rather than to water depth tolerances. High abundance at the outcrop level of the penshell A. maura is consistent with a shoreface setting, probably no more than 20–30 m in water depth. The most abundant species within this group (T. altilira altilira) is the prominent element of an upper shoreface fossil assemblage from the Miocene Angostura Formation (Cantalamessa et al., 2007). Shellbeds of this type, immediately overlying a Glossifungites-demarcated ravinement surface, are regarded as onlap shellbeds and record landward stratal convergence and attenuation during the earliest phases of marine transgression
• LITHOLOGY: Bulk samples consist of poorly lithified sediments (i.e., affected by incipient cementation only). LITHIFICATION: 50–70-cm-thick, mollusk-dominated fossiliferous horizon including widely scattered rip-up clasts with abundant macroborings by lithophagid bivalves (Gastrochaenolites) (Fig. 2B). In section, this shellbed has a simple internal architecture in which the bioclastic components, which are packed densely to loosely in the lower part, pass rapidly upward into a dispersed, matrix-supported biofabric (Fig. 2C). The embedding matrix consists of massive, silty sandstones thoroughly bioturbated by Thalassinoides burrows that form an irregularly shaped network of tunnels and wider chambers.

Size class: macrofossils

• The bioclasts from the bulk sample show a high degree of fragmentation and include a huge number of shell fragments.

Preservation: original aragonite

Collection methods: bulk, surface (in situ), sieve,

• COLLECTOR: By the authors, although not specified. REPOSITORY: Not stated in text. METHODS: Bulk samples, amalgamated from multiple replicates (,30 dm3 each) were collected from different lateral spots of the same fossiliferous horizon, and manual picking at outcrop level, in order to obtain large and rare species. Bulk samples consist of poorly lithified sediments (i.e., affected by incipient cementation only, with rocks easily disintegrable with hydrogen peroxide) that were soaked in a strongly diluted H2O2 and water solution and later washed with fresh water, air dried, and gently sieved through 1 mm mesh screens. Slightly < 1900 fish otoliths were extracted from a 1000 kg cumulative bulk sample amalgamated from multiple replicates collected adjacently over the entire exposed length of the same horizon (lateral spacing between the sampling sites is 100 m or less). Bulk material was reduced to a reasonable size after processing with water, air drying, and sieving (smallest screen 0.5 mm) and otoliths were separated from the final residue by hand picking.

Primary reference: G. Carnevale, W. Landini, L. Radgaini, C. Celma, G. and Cantalamessa. 2011. Taphonomic and paleoecological analyses (mollusks and fishes) of the Súa Member condensed shelled, upper Onzole Formation (Early Pliocene, Ecuador). Palaios 26(3):160-172 [A. Hendy/A. Hendy/P. Holroyd]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 135043: authorized by Austin Hendy, entered by Austin Hendy on 20.10.2012

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Exhaustive for molluscs and fish otoliths. NONENCLATURE: Not an authoritative publication, but with modern nomenclature, and species-resolution identifications.
 Arcida - Arcidae
Anadara sp. Gray 1847 ark
Anadara reinharti Lowe 1935 ark
 Arcida - Glycymerididae
Tucetona cf. strigilata Sowerby 1833 clam
Glycymeris sp. Da Costa 1778 clam
 Pectinida - Pectinoidae
Spondylus sp. Linnaeus 1758 scallop
"Pecten gordus" = Pecten (Pecten) gordus Olsson 1964 scallop
Chlamys sp. Röding 1798 scallop
 Ostreida - Ostreidae
Undulostrea megodon Hanley 1846 oyster
Saccostrea cf. palmula Carpenter 1857 oyster
Ostrea sp. Linnaeus 1758 oyster
Ostrea iridescens Gray 1854 oyster
 Ostreida - Pinnidae
Atrina cf. maura Sowerby 1833 oyster
 Carditida - Carditidae
"Cardita crassicostata" = Cardites crassicostata Sowerby 1825 clam
 Pholadida - Corbulidae
Corbula sp. Bruguière 1789 clam
Caryocorbula amethystina Olsson 1961 clam
 Cardiida - Chamidae
Chama pellucida Broderip 1835 jewel box
Arcinella arcinella Linnaeus 1767 jewel box
 Cardiida - Ungulinidae
Diplodonta sp. Bronn 1831 clam
 Cardiida - Veneridae
"Timoclea squamosa" = Chioneryx squamosa, Lirophora mariae
"Timoclea squamosa" = Chioneryx squamosa Carpenter 1857 venus clam
Lirophora mariae d'Orbigny 1846 venus clam
 Cardiida - Tellinidae
Tellina sp. Linnaeus 1758 tellin clam
 Cardiida - Semelidae
 Cardiida - Cardiidae
Trachycardium sp. Mörch 1853 cockle
 Lucinida - Lucinidae
 Opisthobranchia - Cylichnidae
Acteocina cf. puruha Pilsbry and Olsson 1941 barrel-bubble
 Neogastropoda - Olividae
Oliva splendidula olive snail
 Neogastropoda - Cancellariidae
Cancellaria sp. Lamarck 1799 snail
 Neogastropoda - Cystiscidae
Persicula sp. Schumacher 1817 snail
 Neogastropoda - Mitridae
Mitra musa mitre shell
Mitra ecuadoriana Olsson 1964 mitre shell
 Neogastropoda - Turridae
Turridae indet. Swainson 1840 turrid
Carinodrillia sp. Dall 1919 turrid
Gemmula cf. hindsiana Berry 1958 turrid
 Neogastropoda - Conidae
Conus camaronus cone shell
Conus sp. Linnaeus 1758 cone shell
 Neogastropoda - Pseudomelatomidae
 Neogastropoda - Terebridae
Strioterebrum sp. Sacco 1891 auger snail
Strioterebrum indocayapum Olsson 1964 auger snail
"Terebra cf. subsulcifera" = Terebra (Oreoterebra) subsulcifera Brown and Pilsbry 1911 auger snail
 Vanikoroidea - Eulimidae
 Naticoidea - Naticidae
Polinices hepaticus Röding 1798 moon snail
 Vermetoidea - Vermetidae
Serpulorbis sp. Sasso 1827 worm shell
 Calyptraeoidea - Calyptraeidae
Crucibulum sp. Schumacher 1817 slipper shell
 Sorbeoconcha - Turritellidae
"Turritella altilira" = Turritella (Bactrospira) altilira Conrad 1857 turret shell
Turritella abrupta Spieker 1922 turret shell
 Pyramidelloidea - Pyramidellidae
 Architectonicoidea - Architectonicidae
Architectonica nobilis Röding 1798 sundial
 Dentaliida - Dentaliidae
Dentalium sp. Linnaeus 1758 tusk shell
 Anguilliformes - Congridae
 Acanthomorphata - Opistognathidae
 Pleuronectiformes - Pleuronectidae
 Pleuronectiformes - Cynoglossidae
Cynoglossidae indet. Jordan 1963 flatfish
 Pleuronectiformes - Paralichthyidae
Citharichthys sp. Bleeker 1862 flatfish
 Kurtiformes - Apogonidae
Apogonidae indet. Bonaparte 1846 Cardinalfish
Apogon sp. Lacépède 1802 Cardinalfish
 Ophidiiformes - Ophididae
 Ophidiiformes - Ophidiidae
 Batrachoidiformes - Batrachoididae
Porichthys cf. notatus Girard 1854 toadfish
 Perciformes - Serranidae
? Serranidae indet. Swainson 1839 perch-like fish
 Perciformes - Gobioidei
Gobiidae indet. Bonaparte 1832 goby
 Acanthomorphata - Gerreidae
 Acanthomorphata - Haemulidae
 Acanthomorphata - Sciaenidae
 Gadiformes - Merlucciidae
 Myctophiformes - Myctophidae
Diaphus sp. Eigenmann 1890 lanternfish
Lampadena sp. Goode and Bean 1893 lanternfish
 Clupeiformes -
Anchoa sp. Jordan and Evermann 1927