Post by Infinity Blade on Nov 19, 2016 7:31:30 GMT 5
Dollocaris ingens
Reconstruction of Dollocaris. © @ Andrey Atuchin
Temporal range: Upper (Late) Jurassic; Oxfordian stage (160Ma[1])
Scientific classification:
Life
Domain: Eukaryota
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
(unranked): Bilateria
Clade: Nephrozoa
(unranked): Protostomia
Superphylum: Ecdysozoa
(unranked): Panarthropoda
(unranked): Tactopoda
Phylum: Arthropoda
Class: †Thylacocephala
Genus: †Dollocaris
Species: †D. ingens
Dollocaris ingens is an extinct species of aquatic arthropod of the now extinct Thylacocephala. It lived in what is now France during the Late Jurassic 160 million years ago.[1]
Description and behavior:
One of the most notable features of Dollocaris were its eyes. They were huge and had roughly "18,000 juxtaposed ommatidia each with a corneal lens, a crystalline cone and elongated receptor cells clustered around a central rhabdom." This is an exceptionally high number of omnatidia among any arthropod extant or extinct. The hemispherical eyes provided a wide field of view, giving Dollocaris panoramic vision. Such a characteristic is also known in modern predatory arthropods. Given the nature of its eyes (i.e. compound eyes with small lens diameters), Dollocaris would have needed high light intensities to get enough signal from photons.[1]
The acuity of the eyes can also be determined by determining the inter-omnatidial angle. In Dollocaris it was ~1o, giving it the ability to detect prey from far away and track it down in an effective manner. From this, it can be clearly inferred that Dollocaris was a predator that relied greatly on sight.[1]
However, it appears that the area in which Dollocaris was found in, La Voulte, was poorly illuminated during its time. Since it would have relied on a large to moderate amount of light for its eyes to optimally function, it must have lived in the euphotic zone.[1]
By beating its posterior appendages, Dollocaris could have moved about in the ocean. Its carapace was streamlined, making it easier to move through the water due to reduced drag. That said, the animal did not have long appendages for swimming or a flexible abdomen sticking out from its abdomen. Therefore, it would not have been a fast swimmer. This suggests that it would have been an ambush predator.[1]
Dollocaris had three pairs of appendages, which became larger posteriorly. The terminal ends were claw or pincer-like and the distal ends of the largest appendages had spines. These appendages were used for raptorial purposes; they grasped prey and brought it to the mouth.[1]
References:
[1] Vannier, J.; Schoenemann, B.; Gillot, T.; Charbonnier, S.; Clarkson, E. (2016). Exceptional preservation of eye structure in arthropod visual predators from the Middle Jurassic. Nature Communications 7, Article number: 10320 (2016) doi:10.1038/ncomms10320
Reconstruction of Dollocaris. © @ Andrey Atuchin
Temporal range: Upper (Late) Jurassic; Oxfordian stage (160Ma[1])
Scientific classification:
Life
Domain: Eukaryota
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
(unranked): Bilateria
Clade: Nephrozoa
(unranked): Protostomia
Superphylum: Ecdysozoa
(unranked): Panarthropoda
(unranked): Tactopoda
Phylum: Arthropoda
Class: †Thylacocephala
Genus: †Dollocaris
Species: †D. ingens
Dollocaris ingens is an extinct species of aquatic arthropod of the now extinct Thylacocephala. It lived in what is now France during the Late Jurassic 160 million years ago.[1]
Description and behavior:
One of the most notable features of Dollocaris were its eyes. They were huge and had roughly "18,000 juxtaposed ommatidia each with a corneal lens, a crystalline cone and elongated receptor cells clustered around a central rhabdom." This is an exceptionally high number of omnatidia among any arthropod extant or extinct. The hemispherical eyes provided a wide field of view, giving Dollocaris panoramic vision. Such a characteristic is also known in modern predatory arthropods. Given the nature of its eyes (i.e. compound eyes with small lens diameters), Dollocaris would have needed high light intensities to get enough signal from photons.[1]
The acuity of the eyes can also be determined by determining the inter-omnatidial angle. In Dollocaris it was ~1o, giving it the ability to detect prey from far away and track it down in an effective manner. From this, it can be clearly inferred that Dollocaris was a predator that relied greatly on sight.[1]
However, it appears that the area in which Dollocaris was found in, La Voulte, was poorly illuminated during its time. Since it would have relied on a large to moderate amount of light for its eyes to optimally function, it must have lived in the euphotic zone.[1]
By beating its posterior appendages, Dollocaris could have moved about in the ocean. Its carapace was streamlined, making it easier to move through the water due to reduced drag. That said, the animal did not have long appendages for swimming or a flexible abdomen sticking out from its abdomen. Therefore, it would not have been a fast swimmer. This suggests that it would have been an ambush predator.[1]
Dollocaris had three pairs of appendages, which became larger posteriorly. The terminal ends were claw or pincer-like and the distal ends of the largest appendages had spines. These appendages were used for raptorial purposes; they grasped prey and brought it to the mouth.[1]
References:
[1] Vannier, J.; Schoenemann, B.; Gillot, T.; Charbonnier, S.; Clarkson, E. (2016). Exceptional preservation of eye structure in arthropod visual predators from the Middle Jurassic. Nature Communications 7, Article number: 10320 (2016) doi:10.1038/ncomms10320
