Tamisiocarididae Pates and Daley, 2019
|
publication ID |
https://doi.org/ 10.4202/app.00870.2020 |
|
publication LSID |
lsid:zoobank.org:pub:5FCBD9DE-C9BE-4A8F-9C68-0232D9829401 |
|
persistent identifier |
https://treatment.plazi.org/id/D43B9C40-E17A-FF8F-FF54-F9C8FDADB592 |
|
treatment provided by |
Felipe |
|
scientific name |
Tamisiocarididae Pates and Daley, 2019 |
| status |
|
Family Tamisiocarididae Pates and Daley, 2019
Type genus: Tamisiocaris Daley and Peel, 2010 .
Genera included: Type genus and “ Anomalocaris ” briggsi Nedin, 1995 .
Tamisiocarididae indet.
Fig. 7 View Fig .
Material.—A single partial frontal appendage ( YKLP 12419) from Lihuazhuang section, locality c. 2.5 km southeast of Lihua village, China ( Fig. 1 View Fig ), Cambrian (Stage 4), lower part of Wulongqing Formation, Palaeolenus Biozone (Hu et al. 2010).
Description.—This near complete appendage is composed of 15 approximately square podomeres (counted from the number of endites and rarely observed podomere boundaries), and measures c. 50 mm along the dorsal margin ( Fig. 7 View Fig ). The appendage lacks both proximal and distal ends, but the preserved portion tapers distally ( Fig. 7A View Fig 3 View Fig , A 4 View Fig ). Each podomere bears an elongate and slender endite, subequal in size along the appendage ( Fig. 7 View Fig : en). The best preserved of these endites are longer than the height of the podomere to which they attach and are slightly curved towards the proximal end of the appendage (e.g., Fig. 7A View Fig 4 View Fig : en9). Endites bear short and delicate auxiliary spines, c. 0.5– 1 mm apart, that project at an angle of 120–150° relative to the long axis, from both the proximal and distal margins following a pectinate arrangement ( Fig. 7 View Fig : aux). The presence of dorsal spines cannot be determined, as the dorsal margin of the appendage is not well preserved, especially distally.
Remarks.— YKLP 12419 possesses well-differentiated podomeres bearing endites with auxiliary spines, which is a combination of characters solely known in radiodonts and the recently described deuteropod Kylinxia ( Zeng et al. 2020) . The presence of numerous elongate endites, similar in size and morphology in the entire distal articulated region allows a confident assignment of this fossil to the radiodont family Tamisiocarididae . Indeed, endites alternate long/ short on adjacent podomeres in amplectobeluids, anomalocaridids, and Kylinxia , while there is a marked difference in size and morphology between the proximal and distal (when present) endites of the distal articulated region in hurdiids. A lack of functional articulation and therefore of distal articulated region characterizes the atypical radiodont genus Caryosyntrips .
As only a single row of endites can be observed, the pairing of endites cannot be ascertained in this new taxon. However, it is well-documented from other radiodonts known from many more frontal appendages, such as Anomalocaris canadensis , that the second series of endites often remains concealed within the sediment ( Daley and Edgecombe 2014). Moreover, frontal appendages of hurdiids, the one family with unpaired endites, bear auxiliary spines on the distal margin of endites only, and typically have fewer than 14 podomeres. The presence of auxiliary spines on both distal and proximal faces of endites, and the high podomere count, allow a confident assignment of this new material to the family Tamisiocarididae .
The presence of fine auxiliary spines on both proximal and distal margins of endites is known in the two formally described tamisiocaridid taxa, “ Anomalocaris ” briggsi and Tamisiocaris borealis ( Daley et al. 2013b; Vinther et al. 2014). However, the Guanshan specimen notably differs from both these taxa in the outline of its podomeres, which are square in lateral view, rather than tall and rectangular. We leave this incomplete appendage in open nomenclature as important features, such as the total number of podomeres or the presence of dorsal and terminal spines, cannot be determined. However, we recognize that it represents a new species and probably a new genus of tamisiocaridid radiodont. As such, this specimen extends the palaeogeographic range of the family to the South China palaeocontinent. Other tamisiocaridids are known from the Cambrian, Stage 3 of Laurentia ( Tamisiocaris borealis, Buen Formation ; Daley and Peel 2010; Vinther et al. 2014) and Stage 4 of Gondwana (“ Anomalocaris ” briggsi, Emu Bay Shale ; Daley et al. 2013b) and Laurentia ( Tamisiocaris aff. borealis, Kinzers Formation ; Pates and Daley 2019).
Stratigraphic and geographic range.—Lihuazhuang section, Yiliang county, Yunnan, China. Wulongqing Formation
Palaeolenus Biozone ), Cambrian (Stage 4).
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.