Topic
Diania
About: Diania is a research topic. Over the lifetime, 4 publications have been published within this topic receiving 98 citations.
Papers
TL;DR: D. cactiformis is described as an ‘armoured’ lobopodian from the Chengjiang fossil Lagerstätte (Cambrian Stage 3), Yunnan, southwestern China, remarkable for possessing robust and probably sclerotized appendages, with what appear to be articulated elements.
Abstract: Cambrian fossil Lagerstatten preserving soft-bodied organisms have contributed much towards our understanding of metazoan origins. Lobopodians are a particularly interesting group that diversified and flourished in the Cambrian seas. Resembling 'worms with legs', they have long attracted much attention in that they may have given rise to both Onychophora (velvet worms) and Tardigrada (water bears), as well as to arthropods in general. Here we describe Diania cactiformis gen. et sp. nov. as an 'armoured' lobopodian from the Chengjiang fossil Lagerstatte (Cambrian Stage 3), Yunnan, southwestern China. Although sharing features with other typical lobopodians, it is remarkable for possessing robust and probably sclerotized appendages, with what appear to be articulated elements. In terms of limb morphology it is therefore closer to the arthropod condition, to our knowledge, than any lobopodian recorded until now. Phylogenetic analysis recovers it in a derived position, close to Arthropoda; thus, it seems to belong to a grade of organization close to the point of becoming a true arthropod. Further, D. cactiformis could imply that arthropodization (sclerotization of the limbs) preceded arthrodization (sclerotization of the body). Comparing our fossils with other lobopodian appendage morphologies--see Kerygmachela, Jianshanopodia and Megadictyon--reinforces the hypothesis that the group as a whole is paraphyletic, with different taxa expressing different grades of arthropodization.
73 citations
TL;DR: It is believed that Diania probably belongs within an unresolved clade or paraphyletic grade of lobopodians, and may therefore have evolved before articulated trunk tergites in the immediate arthropod stem.
Abstract: Arising from J. Liu et al. , 526–530 (2011)10.1038/nature09704
; Liu et al. reply
Liu et al.1 describe a new and remarkable fossil, Diania cactiformis. This animal apparently combined the soft trunk of lobopodians (a group including the extant velvet worms in addition to many Palaeozoic genera) with the jointed limbs that typify arthropods. They go on to promote Diania as the immediate sister group to the arthropods, and conjecture that sclerotized and jointed limbs may therefore have evolved before articulated trunk tergites in the immediate arthropod stem. The data published by Liu et al.1 do not unambiguously support these conclusions; rather, we believe that Diania probably belongs within an unresolved clade or paraphyletic grade of lobopodians.
14 citations
TL;DR: The study augments the morphological diversity of Cambrian lobopodians and presents two evolutionary extremes of cuticular ornamentation: one represented by the Humboldt lobopODian, which was most likely entirely “naked”, the other epitomized by †D.
Abstract: Cambrian marine lobopodians are generally considered as predecessors of modern panarthropods (onychophorans, tardigrades, and arthropods) Hence, further study of their morphological diversity and early radiation may enhance our understanding of the ground pattern and evolutionary history of panarthropods Here, we report a rare lobopodian species, †Lenisambulatrix humboldti gen et sp nov (“Humboldt lobopodian”), from the early Cambrian Chengjiang Lagerstatte and describe new morphological features of †Diania cactiformis, a coeval armoured lobopodian nicknamed “walking cactus” Both lobopodian species were similar in possessing rather thick, elongate lobopods without terminal claws However, in contrast to †Diania cactiformis, the body of which was heavily armored with spines, the trunk and limbs of the Humboldt lobopodian were entirely unarmored Our study augments the morphological diversity of Cambrian lobopodians and presents two evolutionary extremes of cuticular ornamentation: one represented by the Humboldt lobopodian, which was most likely entirely “naked”, the other epitomized by †D cactiformis, which was highly “armoured”
10 citations
TL;DR: New observations on D. cactiformis are made using newly collected material, rejecting the evidence for sclerotized, segmented and articulated appendages; instead the appendages compare more closely to lobopods.
Abstract: Cambrian lobopodians have attracted much attention in that they are considered to have close affinities with the origin of arthropods, and recent studies agree that they sample the stem-groups of both Arthropoda and Onychophora. A new lobopodian species, Diania cactiformis Liu et al., 2011, was recently reported from the Chengjiang Lagerstatte (south-west China; Cambrian Series 2). This animal was interpreted as bearing arthropod-like articulated appendages and was resolved as the sister taxon to Arthropoda in a cladistic analysis. A reanalysis of the published dataset did not reproduce the phylogenetic placement of D. cactiformis, and the interpretation of its appendage morphology is controversial. New observations on D. cactiformis are made using newly collected material, rejecting the evidence for sclerotized, segmented and articulated appendages; instead the appendages compare more closely to lobopods. The criteria for defining arthropodized appendages are further discussed through comparative studies...
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2018 | 1 |
| 2014 | 1 |
| 2011 | 2 |