Brachiopods from the Latham Shale Lagerstätte (Cambrian Series 2, Stage 4) and Cadiz Formation (Miaolingian, Wuliuan), California

Abstract

A moderately diverse assemblage of brachiopods from the Latham Shale Lagerstätte (Cambrian Series 2, upper Stage 4) and the upper Cadiz Formation (Miaolingian, Wuliuan), California is described in detail for the first time. The fauna includes both linguliform and rhynchonelliform brachiopods—Hadrotreta primaea (Walcott, 1902), Paterina prospectensis (Walcott, 1884), Dictyonina pannula (White, 1874), and Mickwitzia occidens Walcott, 1908; and Nisusia fulleri Mount, 1981 and Wimanella highlandensis (Walcott, 1886), respectively—together with olenellid trilobites and hyolithids. The fauna differs from other Cambrian Konservat-Lagerstätten (notably Cambrian Series 2 Chengjiang and Guanshan Lagerstätten, eastern Yunnan) in that the brachiopod shell valves in many cases are still preserved with their original mineralization. Moreover, the excellently preserved shale-hosted valves even include cases with exquisite epithelial cell molds, otherwise only seen in acid-etched material from carbonate rocks. The pitted ornamentation in D. pannula closely resembles that described from Ordovician linguliforms. The unusual preservation of N. fulleri provides important clues for ancestral composition of the brachiopod shell. The two articulated rhynchonelliform species probably represent the oldest records of this group from the west Laurentia. The fauna could also represent the earliest onset of the transition from the Cambrian Evolutionary Fauna (CEF) to the Paleozoic Evolutionary Fauna (PEF).

Cambrian (Stage 4 to Wuliuan) brachiopods from Sonora, Mexico

“…Hadrotreta rara ? appears to be most similar to the type species (see Liang et al, 2022), but has a longer dorsal median ridge, although most dorsal valves are fragmented anteriorly, and moreover, the “forked” septum with the dorsal anterior lateral scars (Fig. 7.2, 7.4, 7.5) are not as well developed as in other species of the genus.…”

“…5, 6) from the Arrojos Formation, and they are considered to be conspecific. The Sonoran species is also similar to Dictyonina pannula (White, 1874) (see Liang et al, 2022). Specimens also have been listed and illustrated by Cuen-Romero et al (2018, 2019, 2020) and Noriega-Ruiz et al (2020).…”

The First Report of the Acrotretoid Brachiopod Hadrotreta from the Tsinghsutung Formation Cambrian (Series 2, Stage 4), Guizhou, South China

“…At present, the genus Hadrotreta contains the following species: H . primaea [ 18 , 20 , 28 , 40 , 41 , 42 , 50 ], H . taconica [ 25 ], H .…”

“…At present, Hadrotreta is currently known to be from Nevada [ 18 , 40 , 41 , 42 , 52 ], California [ 28 ], Pennsylvania [ 22 ], Canada [ 25 ], the Himalayas [ 23 ], Australia [ 20 , 24 ], Turkestan [ 16 ], Uzbekistan [ 17 ], Novaya Zemlya [ 26 , 37 ], Kazakhstan [ 19 ], Argentina [ 29 ], the Far East [ 21 ], and Mexico [ 27 ], from sites with a geological age ranging from Cambrian Age 4 to the Miaolingian Epoch ( Figure 5 a). Hadrotreta occurred in Pennsylvania, Nevada, Canada, and Mexico during the Cambrian Age 4 ( Figure 5 a), where it was located in Laurentia ( Figure 5 b).…”

“…Zhang et al [ 5 , 12 , 13 ] not only studied the relationship between the ontogenetic stage of Eohadrotreta , their distribution of epidermal cells, and the attachment area of their soft body, but also explored the systematic relationship between Eohadrotreta and other lingulid brachiopods, providing an excellent basis for further research on the early origin and expansion of brachiopods. As one of the oldest and most cosmopolitan acrotretoids, Hadrotreta has been reported from the Cambrian Series 2 to Miaolingian in Nevada, California, Pennsylvania, Canada, Turkestan, Uzbekistan, Novaya Zemlya, Kazakhstan, the Far East, Australia, the Himalayas, and Mexico [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. In addition, Hadrotreta ?…”