Tertiapatus dominicanus
| Tertiapatus dominicanus | ||||||||||||
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| Miocene | ||||||||||||
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| Scientific name | ||||||||||||
| Tertiapatus dominicanus | ||||||||||||
| Poinar , 2000 |
Tertiapatus dominicanus is a fossil velvet worms - kind , in amber from the Dominican Republic on the Caribbean -Insel Hispaniola was found. Along with Succinipatopsis balticus, it is the only known representative of this animal strain from the entire Tertiary .
Due to the coincidence of the site with the range of modern velvet worms from the family of Peripatidae, it cannot be ruled out that the species is a member of this taxon - however, due to the conservation status of the fossil, it is not possible to prove this.
The holotype of the species is now in the Amber Museum of Oregon State University in the US state of Oregon .
Appearance and state of preservation
As with Succinipatopsis balticus , only part of the carcass has been preserved. This is a little more than 4 millimeters long and has 19 pairs of legs; however, when fully assembled, their number was probably twice as high. The legs themselves are approximately 0.2 to 0.25 millimeters long and between 0.12 and 0.20 millimeters in diameter; in contrast to the limbs of the modern species, they apparently have no claws at the foot end. As with the modern species, however, the mouth is on the ventral side.
Otherwise, the body has two approximately 0.45 millimeter long antennae at its front end, which show a superficial ring, but otherwise no pattern. Their maximum diameter is about 0.1 millimeters; there is a small eye at the antenna base.
Below the antennae, but also on the front of the head, a pair of oral papillae can be seen, structures that, in today's species, are used for defense and for catching prey by spraying a slime that becomes sticky in the air. That this was already the function of the organs of Tertiapatus dominicanus , about 0.18 millimeters long and 0.08 millimeters wide , can be inferred from the discernible dark spots in close proximity to the papillae on both sides of the head, which are interpreted as mucus deposits. Since modern species spray their adhesive liquid even in stressful situations, it could be a reaction of the animal to the inclusion by the resinous substrate that later hardened to amber.
The slightly thin and red-brown colored outer skin or epidermis has numerous fine hairs only about 0.025 to 0.038 millimeters long with a diameter of about 0.01 millimeters. Since the pigments of the skin can be seen diffusing into the amber, they are probably in organic solvents, such as occur frequently in tree resins, soluble - which even in the modern representatives of peripatidae, but not with her sister group to a property peripatopsidae find leaves.
Age and classification
The amber in which the fossil was found was apparently formed by highly resinous trees of the genus Hymenea , a member of the carob family (Caesalpinioideae). He and is now estimated to be 17 and 20 million years old; thus the life of the species falls into the geological epoch of the Miocene .
Even today there are columbus on the Caribbean island of Hispaniola, all of which belong to the Peripatidae family. It is not known whether they are descendants of Tertiapatus dominicanus ; the solubility of their skin pigments can only be taken as an indication.
Taxonomically, the species is combined with Succinipatopsis balticus to form a taxon Tertiapatoidea. This is probably to be regarded as a paraphyletic form taxon, since it does not include all descendants of the group's last common ancestor.
Together with a Cretaceous fossil from Myanmar , Cretoperipatus burmiticus , and the species Helenodora inopinata , which was preserved from the geological epoch of the Carboniferous , the two tertiary species make up the total population of fossil pebbles.
literature
- 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
- G. Poinar, Fossil Velvet Worms in Baltic and Dominican Amber, Onchychophoran Evolution and Biogeography , Science, 273 , 1996, page 1370