Laguna del Hunco (Eocene of Argentina)

Where: Chubut, Argentina (42.3° S, 70.0° W: paleocoordinates 44.8° S, 60.0° W)

• coordinate stated in text

• local area-level geographic resolution

When: Laguna del Hunco Formation, Early/Lower Eocene (55.8 - 48.6 Ma)

• The material comes from the early Eocene Tufolitas Laguna del Hunco, outcropping near the Laguna del Hunco, Chubut, Argentina. The Laguna del Hunco biota was deposited in tuffaceous mudstones and sandstones. The sedimentation was accompanied by synchronous felsic volcanic events mainly in an intracaldera setting, resulting in foliated domes and lavas, silts, hyaloclastites, small and pumiceous ignimbrites, and rhyolithic dykes (Aragon and Mazzoni, 1997).

Environment/lithology: crater lake; tuffaceous mudstone and tuffaceous sandstone

• Bachmannia chubutensis lived during the time of the early Eocene climatic optimum, when tropical plant taxa and warm, equable climates reached middle latitudes of both hemispheres (Wilf et al., 2005). At this moment, the Laguna del Hunco area was located near the southern limit of Neotropical floral influence, certainly a frost-free humid biome (Romero, 1986). As no significant uplift of the Southern Central Andes occurred before the Miocene (Marshall and Salinas, 1990), the Eocene Laguna del Hunco area lay at a low elevation, and a significant maritime influence moderated its climate. As sedimentation was accompanied by synchronous volcanic events mainly in the intracaldera setting (Aragon and Mazzoni, 1997) gases in water could have occasionally provoke massive fish kills. Specimens are relatively twisted.
• The Laguna del Hunco biota was deposited in tuffaceous mudstones and sandstones

Size class: macrofossils

Preservation: adpression

Primary reference: M. M. Azpelicueta and A. L. Cione. 2011. Redescription of the Eocene Catfish Bachmannia chubutensis (Teleostei : Bachmanniidae) of Southern South America. Journal of Vertebrate Paleontology 31(2):258-269 [C. Jaramillo/G. Ballen]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 140477: authorized by Carlos Jaramillo, entered by Gustavo Ballen on 10.03.2013, edited by Elena Stiles

Creative Commons license: CC BY (attribution)

Taxonomic list

 Siluriformes - Bachmanniidae
Bachmannia chubutensis n. gen. n. sp.
Bachmannia chubutensis n. gen. n. sp. Dolgopol 1941 catfish
MLP 40-V-17–1 (holotype); CIC: 75/1, 75/3–8, 75/10–14, 75/16–18. MACN PV: 19785–19806. MLP 35-X-4–8, MLP 40-V-17–3 (holotype of Arius argentinus), MLP: 40-V-17–4/6/7/9/11/14/15/17/19/21/23/24, 40-V-20–1, 77-VI- 6–1/2/3/4. PVL: 4305–4307, 4309–4316, 4318–4331, 4365–4367, 4369–4370. MPBAR: 1091–1044. MPEF-PV: 1514/1516/1519, 1524a–b, 1525a–b, 1526–1527, 1537/1545/1549/1551, 1555a–b, 1900a–b, 1901a–b, 1902–1905 (all non-types).
 Ginkgoales -
Ginkgoites patagonica Villar de Seoane et al. 2015