Occurrence of the hurdiid radiodontCambrorasterin the middle Cambrian (Wuliuan) Mantou Formation of North China

Abstract

The hurdiid radiodont Cambroraster is characterized by a prominent horseshoe-shaped head carapace, which bears conspicuous posterolateral spinous processes and covers half of the body length, and a pair of frontal appendages possessing rake-like endites. Here we report the discovery of characteristic central and lateral elements as well as a possible appendage endite for Cambroraster from the Cambrian Wuliuan Mantou Formation of North China. This discovery suggests that Cambroraster had dispersed over a wide biogeographic range and expands the geographic range of Hurdiidae. The increasing discoveries of exceptionally preserved fossils in the Upper Shale Member of the Mantou Formation indicate that this horizon is a promising Burgess Shale–type Lagerstätte.

Disparate compound eyes of Cambrian radiodonts reveal their developmental growth mode and diverse visual ecology

“…The radiodont head also features a range of sclerites or carapace elements that have only come to light in the past 15 years ( 15 ). These include separate dorsal and lateral cephalic plates [as in Anomalocaris ( 10 , 16 ), Amplectobelua ( 13 ), and Lyrarapax ( 6 )], an integrated carapace composed of dorsal and lateral elements [as in Hurdia ( 17 )], or in one unusual example, an expanded, horseshoe-shaped carapace [as in Cambroraster ( 10 , 18 , 19 )].…”

Paleomagnetic insights into the Cambrian biogeographic conundrum: Did the North China craton link Laurentia and East Gondwana?

“…Recently, some exceptionally preserved fossils were reported from the middle Cambrian strata in the NCC, and a few of the fossil species have not been confidently reported outside Laurentia thus far (Sun et al, 2020a(Sun et al, , 2020b. For example, the arthropods Sidneyia and Cambroraster, remarkable animals from the Burgess Shale biota (Wuliuan; British Columbia, Canada), have been discovered recently from the Wuliuan shales in the eastern NCC (Sun et al, 2020a(Sun et al, , 2020b. The Burgess Shale-type fossil biotas have been found from most continents in the Cambrian, but common fossil components among these biotas are usually pelagic and nektonic organisms.…”

“…Interesting questions are when and how the trilobites in different realms began to communicate with each other. The North China craton (NCC) has long been considered to have a close biogeographic association with East Gondwana because it yields the typical redlichiid trilobites (e.g., Zhang, 2003), but recent discoveries of a few characteristic fossils of Laurentia in Wuliuan shales in the eastern NCC (Sun et al, 2020a(Sun et al, , 2020b, together with the mixture of middle and late Cambrian trilobites among the NCC, East Gondwana, and Laurentia (e.g., Zhang, 2003;Álvaro et al, 2013;Collette, 2014;Wernette et al, 2020), prompt us to investigate the role of the NCC in biogeographic changes between East Gondwana and Laurentia in the middle to late Cambrian.…”

Furongian (Jiangshanian) occurrences of radiodonts in Poland and South China and the fossil record of the Hurdiidae

“…1B for possible evidence of the contrary). Accordingly, we follow the terminology first introduced in the Hurdiidae diagnosis of Lerosey-Aubril & Pates (2018) , and describe hurdiid frontal appendages as composed of: (1) a proximal region (or shaft/peduncle sensu Pates, Daley & Butterfield, 2019 ) typically composed of rarely more than one podomere (but see Lerosey-Aubril & Pates, 2018 ; Moysiuk & Caron, 2021 ), and usually associated with a single (absent in Cambroraster , possibly two in Pahvantia ) distally-located endite that differs in size (narrower and usually shorter), shape, or orientation from intermediate endites; (2) an intermediate region of classically five or six podomeres (possibly up to eight podomeres in Cordaticaris ; Sun, Zeng & Zhao, 2020b ), which are associated with long (length of endite >height of corresponding podomere), typically laminiform endites; and (3) a distal region that includes up to six podomeres (e.g., Stanleycaris ; Moysiuk & Caron, 2021 ) bearing much shorter, spiniform endites or no endites at all. In addition, when applied to the appendage: proximal and distal refer to the parts closest to or furthest from its insertion site on the body, respectively; ventral to the typically concave margin bearing the endites, and dorsal to the usually convex margin opposite to it.…”

“…(2) an intermediate region of classically five or six podomeres (possibly up to eight podomeres in Cordaticaris; Sun, Zeng & Zhao, 2020b), which are associated with long (length of endite >height of corresponding podomere), typically laminiform endites; and (3) a distal region that includes up to six podomeres (e.g., Stanleycaris; Moysiuk & Caron, 2021) bearing much shorter, spiniform endites or no endites at all. In addition, when applied to the appendage: proximal and distal refer to the parts closest to or furthest from its insertion site on the body, respectively; ventral to the typically concave margin bearing the endites, and dorsal to the usually convex margin opposite to it.…”