Abstract
Stem-group euarthropods are important for understanding the early evolutionary and ecological history of the most species-rich animal phylum on Earth. Of particular interest are fossil taxa that occupy a phylogenetic position immediately crownwards of radiodonts, for this part of the euarthropod tree is associated with the appearance of several morphological features that characterize extant members of the group. Here, we report two new euarthropods from the Cambrian Stage 4 Guanshan Biota of South China. The fuxianhuiid Alacaris? sp. is represented by isolated appendages composed of a gnathobasic protopodite and an endite-bearing endopod of at least 20 podomeres. This material represents the youngest occurrence of the family Chengjiangocarididae, and its first record outside the Chengjiang and Xiaoshiba biotas. We also describe Lihuacaris ferox gen. et sp. nov. based on well-preserved and robust isolated appendages. Lihuacaris ferox exhibits an atypical combination of characters including an enlarged rectangular base, 11 endite-bearing podomeres and a hypertrophied distal element bearing 8–10 curved spines. Alacaris? sp. appendages display adaptations for macrophagy. Lihuacaris ferox appendages resemble the frontal appendages of radiodonts, as well as the post-oral endopods of chengjiangocaridid fuxianhuids and other deuteropods with well-documented raptorial/predatory habits. Lihuacaris ferox contributes towards the record of endemic biodiversity in the Guanshan Biota.
Highlights
Euarthropods, a major group whose extant representatives include chelicerates, myriapods and pancrustaceans, comprise over 80% of animal biodiversity today [1]
We describe isolated appendages that can be ascribed to previously unknown stem-group euarthropods from the Guanshan Biota (Cambrian: Stage 4) of South China, including a fuxianhuiid, and a new problematic taxon with possible close affinities with either radiodonts or fuxianhuiids
Alacaris? sp., the second fuxianhuiid reported from this exceptional biota, represents both the first occurrence of the Chengjiangocarididae in these beds and the youngest record of this fuxianhuiid family to date
Summary
Euarthropods, a major group whose extant representatives include chelicerates (e.g. horseshoe crabs and arachnids), myriapods (e.g. millipedes and centipedes) and pancrustaceans (e.g. insects and crustaceans), comprise over 80% of animal biodiversity today [1]. Much of our understanding of euarthropod origins and early evolution comes from exceptional fossil deposits that preserve non-biomineralized tissues, such as legs, eyes and guts. Exceptional fossils illuminate our understanding of the relationships of modern euarthropod groups [3] and reveal the polarity of characters that accompanied the evolution from soft-bodied and annulated lobopodian ancestors to sclerotized segmented crown-group euarthropods [2,4,5,6,7,8,9,10]. Among the key characters that are recognizable among the so-called lower stem-group euarthropods (sensu Ortega-Hernández [6]) include the presence of paired serially repeating digestive glands, exemplified by the large-bodied lobopodians Jianshanopodia and Megadictyon [8], and swimming flaps in the more derived ‘gilled lobopodians’ Kerygmachela and Pambdelurion The presence of arthropodization and well-developed compound eyes, some of the most recognizable morphological features of modern representatives of Euarthropoda, appeared within the stem-lineage, among the radiodonts [5,15]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
