| Andiva | |
|---|---|
 | |
| Fossil ofAndiva ivantsovi | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | †Proarticulata |
| Genus: | †Andiva Fedonkin, 2002 |
| Species: | †A. ivantsovi |
| Binomial name | |
| †Andiva ivantsovi Fedonkin 2002 | |
Andiva ivantsovi is aVendianfossil, identified to be abilateriantriploblastic animal in theEdiacaranphylumProarticulata, known from theWinter Coast,White Sea,Russia. It was first discovered in 1977, and described as a new species in a newgenus byMikhail Fedonkin in 2002.[1] It lived about 555 million years ago. Fossils ofAndiva also occur inSouth Australia.[1][2] All known fossils ofAndiva are external molds.[3]
Andiva was between 6 and 10 cm (2.4 and 3.9 in) long and from 4 to 5.5 cm (1.6 to 2.2 in) wide, with a bilaterally symmetrical shape, larger on the anterior end and narrower at the posterior. The anterior part features a smooth "fringe" followed by a surface "covered by fine ribs and sutura",[1] also described as a "quilt" with narrow, tightly packed chambers[3] The symmetry of these ribs is aglide symmetry, that is, in which the corresponding segments on the left and right sides do not line up, but are staggered. This is a feature shared by other forms belonging to the proposedtaxonProarticulata.
The original reconstruction by Fedonkin proposed that the ridged surface was a convex, thincarapace made of a chitin-like, non mineralized substance, protecting the animal while "creeping or gliding" over the sea bed. In the same reconstruction, the smooth zone was considered an imprint of the soft tissue beneath the dorsal carapace.[1]
Andiva is often found together with other species from the Ediacara biota, likeDickinsonia,Yorgia,Kimberella,Brachina,Parvancorina,Tribrachidium and others.[1]
| Proposed cladogram of the relationships betweenDipleurozoa, according to Dzik (2003) |
Morphologically,Andiva most closely resemblesOvatoscutum,Chondroplon and, more distantly,Dickinsonia, as part of the proposedphylumProarticulata.[1]Archaeaspinus andCyanorus have also been directly compared to it.[4]
Jerzy Dzik includesAndiva in theDipleurozoa, withChondroplon as the closest relative, separated fromDickinsonia and closer toYorgia,Praecambridium,Archaeaspinus andVendia, since all of them are sharing a dextrally bent dorsal medial chamber.[3]