Ilyodes
Helenodora inopinata is an extinct species of velvet worms - the geological epoch of the Carboniferous. The fossil was found in siderite from the U.S. state of Illinois and is the earliest undisputed evidence of this animal strain.
The species was first described in 1980 and is named after the finder of fossils Helen Piecko; The scientific name means " Helene unexpected gift ." Both the holo and a parameter type of the species are now in the Field Museum of Natural History in Chicago.
Features
The two known specimens of the species are characterized by an approximately six inches long and an inch wide, worm-like body on which are located at regular intervals at least 21 stub -like abdominal side positioned pairs of legs. On one of these legs, which are about two to three millimeters long, two small, about half a millimeter long claws could be identified.
On the body surface are per segment about nine rings identify where there are numerous small elevations, which are interpreted as papillae. These are arranged in longitudinal rows, which extend at a distance of about one- third of a millimeter to one another.
The head region is poorly preserved. Although an unambiguous assignment is not possible, but a black spot near the ( assumed ) body front end is interpreted as each jaw; makes this identification, so the mouth was already lying on the abdomen side like in the modern representatives of the animal strain. Whether the front two pairs of limbs can be interpreted even as antennas or as Oralpapillen, however, is quite unclear. ( The former are modern Stummelfüßern the detection of potential prey, temptation, by spraying a sticky mucus to catch prey. )
Reference and habitat
Helenodora inopinata was found in siderite, who hails from the so-called Francis Creek Shale in the northern part of the U.S. state of Illinois. He is assigned to the geological period of the middle Pennsylvanian, itself falls into the epoch of the Carboniferous, and are more than 300 million years old.
The habitat of the animal is no longer exactly reconstructed, as well as in agriculture, freshwater and marine living forms can be found in Francis Creek Shale. But similarities to the modern, exclusively terrestrial forms predominantly speak for a terrestrial lifestyle.
Scientific classification
Due to the numerous stub feet it can be considered relatively sure that Helenodora inopinata the Stummelfüßern named after this property ( Onychophora ) is to be allocated. The species is thus the earliest undisputed discovery of a representative of that taxon.
From the epochs of the Cambrian and Ordovician, however, a number of fossils are known which are traditionally also considered to be members of the velvet worms, about Aysheaia pedunculata, auerswaldae Xenusion or Hallucigenia fortis. On cladistic principles -based studies, these and similar forms see but sometimes referred to as stem lineage representatives of a taxon of tardigrades ( Tardigrada ) and arthropods ( Arthropoda ) ( insects, spiders, crustaceans, and others). If this view were correct, the Cambrian forms would be part of the sister group of the velvet worms and would not fall even in this taxon; Helenodora inopinata would then indeed the earliest known form of modern velvet worms.
If, however, the traditional view proves correct, the type includes at least a huge time gap between the Cambrian and Ordovician forms a part, and the Cretaceous type Cretoperipatus burmiticus, which has been preserved in amber from Myanmar, on the other hand. Together with two types Succinipatopsis balticus and Tertiapatus dominicanus from the Tertiary, they form the entire fossil record of the velvet worms.