The hanging wall boundary is also sharply defined facially and characterized by the erosive overburden with terrestrial sediments of various locally widespread strata of the Exter Formation (Malschenberg Clay or Sandstone, Contorta Clay, Tübingen Sandstone) or, in the case of the more extensive Upper Keuper Hiatus, directly with the dark marine mudstones of the Hettangian onwards Black Jurassic.

[1][2] The Trossingen Formation itself consists of fairly uniform, reddish-brown to red, sometimes purple claystones with occasional layers of calcareous nodules (hence the name “Knollenmergel”).

They contain calcitic replacements of small roots and show signs of pedogenic processes, including mud cracks and pseudobreccias.

[5] The Trossingen Formation’s excavation history dates back to the early 20th century when a schoolboy stumbled upon dinosaur bone fragments at a site known as "the Rutschete".

[6] Friedrich von Huene, aware of the site since 1904 but initially lacking funds, launched his own major excavation in 1921, supported by the American Museum of Natural History and local entrepreneurs.

Huene originally theorized that the dinosaurs perished in an arid desert setting but later modified his view to suggest that the animals died of exhaustion near a muddy water source.

Seemann refuted Huene’s desert hypothesis, instead proposing that the region once held a lake, and supported the idea that many Plateosaurus specimens became trapped in mud.

His meticulous field notes and maps provided a detailed record of the site, though much of the material was later destroyed in World War II.

Later studies, including those by Weishampel in the 1980s and Sander in 1992, refined theories on the formation’s depositional history, emphasizing miring as a key factor in preserving the dinosaurs.

Over multiple campaigns, new fossil-bearing layers were identified, revealing additional Plateosaurus skeletons and providing fresh insights into the site’s sedimentology and paleoenvironment.

The presence of features like pedogenic slickensides, pseudoanticlines, and deep desiccation cracks indicates that the sediments underwent significant soil formation processes.

The Red-Brown Beds, distinct in color and composition, likely represent a more arid phase, contrasting with the more humid conditions inferred for the purple vertisol layers.

The overall environmental picture is one of a floodplain subject to periodic drying and wetting, supporting intermittent vegetation and experiencing long-term soil development processes.