Injuries and molting interference in a trilobite from the Cambrian (Furongian) of South China

Abstract

An injured Shergoldia laevigata Zhu, Hughes & Peng, 2007 (Trilobita, Asaphida) was collected from the Furongian of Guangxi, South China. The injuries occurred in the left thoracic pleurae possessing two marked V-shaped gaps. It led to substantial transverse shortening of the left pleural segments, with barely perceptible traces of healing. This malformation is interpreted as a sub-lethal attack from an unknown predator. The morphology of injuries and the spatial and temporal distribution of predators indicated that the predatory structure might have been the spines on the ganathobase or ganathobase-like structure of a larger arthropod. There were overlapped segments located in the front of the injuries, and slightly dislocated thoracic segments on the left part of the thorax, suggesting that the trilobite had experienced difficulties during molting. The freshly molted trilobite had dragged forward the old exuvia causing the irregular arrangement of segments. This unusual trilobite specimen indicates that the injuries interfered with molting.

New records of injured Cambrian and Ordovician trilobites

“…In the last decade alone, a marked surge in publications documenting these abnormal specimens has occurred. The majority of these works have considered abnormal specimens in the context of trilobite paleobiology and paleoecosystems (Budil et al, 2010; Zamora et al, 2011; Fatka et al, 2015, 2021; Cheng et al, 2019; Bicknell and Pates, 2020; Bicknell and Smith, 2021; Bicknell et al, 2021b; Foster, 2021; Zong, 2021a, b). Population-based data have been presented to explore injury patterns and lateralization in the trilobite fossil record (Pates et al, 2017; Bicknell et al, 2019; Pates and Bicknell, 2019).…”

A new bilaterally injured trilobite presents insight into attack patterns of Cambrian predators

“…As this rotated segment lacks shortening or distortion ( Fig. 2C ), this reflects either taphonomic alteration or displacement during molting ( Zong, 2021a ).…”

“…However, the extent of exoskeletal regeneration can be considered a proxy for understanding the timing of attacks and subsequent recovery ( e.g. , Cheng et al, 2019 ; Zong, 2021a ). To expand on this line of enquiry, we describe a malformed redlichiid trilobite from the Cambrian-aged Balang Formation (western Hunan, South China).…”

First confident evidence of moulting in eodiscid trilobites from the Cambrian Stage 3 of South China

“…Museum collections) without a sedimentological and taphonomical context (see Corrales-García et al 2020). The associated behaviour dealing with moults such as cryptic or synchronized moulting also has been explored and discussed (Rustán et al 2011;Zong et al 2016;Zong & Gong, 2017;Corrales-García et al 2020;Zong, 2021;Zong & Gong, 2022). However, so far, only one record of moulting in eodiscid trilobites has been reported from the Kaili biota (Lin & Yuan, 2009).…”

“…2016; Zong & Gong, 2017; Corrales-García et al . 2020; Zong, 2021; Zong & Gong, 2022). However, so far, only one record of moulting in eodiscid trilobites has been reported from the Kaili biota (Lin & Yuan, 2009).…”