Succinipatopsis balticus
| Succinipatopsis balticus | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Eocene | ||||||||||||
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| Scientific name | ||||||||||||
| Succinipatopsis balticus | ||||||||||||
| Poinar , 2000 |
Succinipatopsis balticus is a fossil velvet worms - kind , in Baltic amber was found. Besides Tertiapatus dominicanus, it is the only species known from the geological age of the Tertiary . For the understanding of the tribal history of the velvet worms, it is particularly informative because it shows that they once had a much wider geographical distribution than the spatial distribution of modern species suggests.
The holotype of the species is now in the amber collection of Oregon State University in the US state of Oregon .
Structure and state of preservation
The only known specimen of the species is only partially preserved. It is about 8 millimeters long and shows a total of eight pairs of legs - the actual number of the corresponding segments was probably much higher and is estimated at eighteen to twenty. The clawless legs themselves are about 1.0 millimeter long and about 0.7 millimeters in diameter.
Other recognizable features of the fossil are two antennae about 2.5 millimeters long and slightly more than 0.5 millimeters in diameter, the mouth located between the first pair of legs and two so-called oral papillae , which, as in today's species, are probably used to catch mucus could splash in defense. With a length of about 2 millimeters, they are slightly longer than the legs to which they are probably homologous .
The black outer skin or epidermis does not show any ringing or ornamentation, in contrast to many of the velvet worms living today.
Age and importance
The amber in which Succinopatopsis balticus was found comes from the geological period of the Eocene ; it can be dated to an age of 44 million years and was very likely formed by a species of the pine family (Pinaceae).
The importance of the find for the elucidation of the tribal history of the modern velvet worms lies on the one hand in its uniqueness - together with Tertiapatus dominicanus it is the only species preserved from the entire Tertiary, since the next older find, Cretoperipatus burmiticus from Myanmar , dates from the Cretaceous and with lived about 56 million years earlier at an age of 100 million years. The fossil therefore attests to the continuous existence of a terrestrial columbus line since that time.
Even more significant, however, is the fact that the fossil came from the Baltic States. While the current species of colobus show a so-called Gondwana distribution, that is, they can probably all be traced back to populations in this former supercontinent, Succinopatopsis balticus is difficult to derive from a Gondwana population. This can be seen as significant evidence for the thesis that the velvet worms conquered the country not only in Gondwana, but also independently of it on other continents. Since they are no longer to be found in the temperate zones of the north today, they should have died out there in the subsequent period. At the moment, however, there are no supporting finds that could further substantiate this thesis.
Taxonomically, the species is combined with Tertiapatus dominicanus to form a taxon Tertiapatoidea. However, this is presumably to be viewed as a paraphyletic form taxon as it does not include all descendants of the group's last common ancestor.
literature
- G. Poinar, Fossil velvet worms in Baltic and Dominican Amber, Onychophoran evolution and biogeography , Science, 273 , 1996, page 1370,
- G. Poinar, Fossil onychophorans from Dominican and Baltic Amber: Tertiapatus dominicanus ng, n.sp. (Tertiapatidae n. Fam.) And Succinipatopsis balticus ng, n. Sp. (Succinipatopsidae n. Fam.) With a proposed classification of the subphylum Onychophora. , Invertebrate Biology, 119 , p.104 abstract