Oberegg north of Auenstein (Jurassic to of Switzerland)

Also known as Canton Aargau

Where: Brugg, Switzerland (47.4° N, 8.1° E: paleocoordinates 37.5° N, 17.6° E)

• coordinate stated in text

• outcrop-level geographic resolution

When: Hauptrogenstein Formation, Bajocian to Bajocian (170.3 - 166.1 Ma)

• Te studied interval belongs to the lower Hauptrogenstein Formation. It is of middle Bajocian to early Bathonian age.

• group of beds-level stratigraphic resolution

Environment/lithology: deep subtidal; lithified marl

• Sedimentary structures of some calcarenitic strata imply their tempestitic origin. These sedimentological features suggest a depositional water depth above the storm wave base on a carbonate ramp.
• PIMUZ A/III 5279 was discovered in the marly facies of the Lower Acuminata beds, which are about 8 m thick. At the Oberegg site, the facies is clayey to marly, with layers having a slightly elevated carbonate content, horizons with limestone concretions, usually containing some ooids and some calcarenitic beds. The marls are rich in sand and silt, indistinctly bedded and bioturbated.

Size class: macrofossils

• PIMUZ A/III 5279 (holotype) consists of numerous disarticulated vertebral centra, neural arches and ribs, two partial clavicles, and a nearly complete disarticulated cranium. Preserved cranial elements include an almost complete braincase, the parietals, some of

•the circumorbital area, a large portion of the palate, and most of the jaws including complete premaxillae and dentaries. Most of the vertebrae and ribs are from the

•cervical and dorsal regions but there are a few anterior caudal elements present. Te skull and selected postcranial bones such as cervical vertebrae and the clavicles are completely prepared free of matrix. Much of the posterior skeleton remains partially embedded in the matrix. External bone tissue is pristinely preserved, but in many

•elements, extensive remineralization of endosteal tissue has occurred, which hampered CT-scanning and may hamper potential future histological studies.

Collected in 2004

• Most of it was originally excavated by private collector Elmar Meier and acquired by the PIMUZ in 2019. Subsequent expeditions by the PIMUZ to the original location unearthed additional material, namely the right angular and right jugal. Te main part of the specimen was extracted in multiple blocks and many small fragments

Primary reference: F. Miedema, D. Bastiaans, T. M. Scheyer, C. Klug, and E. E. Maxwell. 2024. A large new Middle Jurassic ichthyosaur shows the importance of body size evolution in the origin of the Ophthalmosauria. BMC Ecology and Evolution 24(34):1-25 [E. Vlachos/F. Aspromonte]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 234449: authorized by Evangelos Vlachos, entered by Franco Aspromonte on 12.04.2024

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Reptilia
 Loricata -
Machimosaurini indet.
Machimosaurini indet. Jouve et al. 2016 marine crocodile
PIMUZ A/III 5281a a-b (two larger tooth crowns), ; PIMUZ A/III 5281c (smaller tooth crown)
 Ichthyosauria - Ophthalmosauridae
Argovisaurus martafernandezi n. gen. n. sp.
Argovisaurus martafernandezi n. gen. n. sp. Miedema et al. 2024 ichthyosaur
PIMUZ A/III 5279 (holotype)