Juracimbrophlebia
| Juracimbrophlebia | ||||||||||||
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Artistic reconstruction of Juracimbrophlebia ginkgofolia on Yimaia capituliformis |
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| Temporal occurrence | ||||||||||||
| late Middle Jurassic ( Bathonian - Callovian border) | ||||||||||||
| 164 to 165 million years | ||||||||||||
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| Scientific name | ||||||||||||
| Juracimbrophlebia | ||||||||||||
| Wang , Labandeira , Shih & Ren , 2012 | ||||||||||||
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Juracimbrophlebia is a genus of the beaked flies (Mecoptera) from the extinct family of the Cimbrophlebiidae . The representatives of the genus lived in the late Middle Jurassic on the Bathonium - Callovium border in what is now northeastern China. A uranium-lead dating using SHRIMP and an argon-argon dating suggest dating around 164 to 165 million years ago . All the fossils found so far are from the Jiulongshan formation near the village Daohugou the municipality of Shantou in circles Ningcheng (Autonomous Region Inner Mongolia ). The genus name Juracimbrophlebia is a combination of the word Jura and Cimbrophlebia , the type genus of the family Cimbrophlebiidae. The specific epithet of the only known species J. ginkgofolia results from the similarity of the wings of the animals with the leaves of the ginkgo plant Yimaia capituliformis . This plant species died out between the Jura and the Cretaceous , and presumably with it the Juracimbrophlebia , which wereadapted to them and which no longer appeared in the Lower Cretaceous. Their presumed interaction shows one of the earliest examples of mutualistic interrelationship between plants and insectsdocumented in the first description in 2012in the time before the emergence of the opalescent , which took place at least during the time of the formation of the Jiulongshan Formation and thus perhaps over a million Lasted for years.
features
As far as can be seen from the fossils obtained, the body of the animals is around 38.5 millimeters long. The head is flattened dorsally and has thread-like antennae , which are covered with numerous setae . The protruding compound eyes take up most of the sides of the head. Three point eyes ( ocelli ) are arranged in a triangle. The “beak” (rostrum) typical of the order is elongated and gradually tapers to its tip. The fossil thorax is poorly preserved and somewhat deformed. It is 6.8 millimeters long and 3.7 millimeters wide. The prothorax is arched in front, the metathorax is well separated and clearly shows the scutellum and prescutum . As with most mosquito-like species (Bittacidae; Mecoptera), the legs are very long and slender. They are strongly fluffed in a ring shape. The front and middle legs are partially preserved in fossil form and extended forward. The hind legs are modified for gripping and become slender. Their thighs ( femora ) are approximately 11.6 millimeters, their rails ( tibia ) 16.4 millimeters and their first tarsal segment (basitarsus) is 2.9 millimeters long. The spurs of the rails are elongated.
The front wings are slightly wider than the hind wings and are at least 32.4 millimeters long. At the base (proximal) they are a minimum of 2.1 millimeters wide, before the rounded tip they are a maximum of 8.9 millimeters wide. The forewings show a light color and have several transparent spots. The wing membrane resembles the leaves of the ginkgo plant genus Yimaia , but also other species of the fossil beaked fly family Cimbrophlebiidae and is clearly wrinkled. The shape of the wing veining is typical of that of the Cimbrophlebiidae family: The subcostal vein ( Sc) ends at the costal vein (C), about two thirds of the wing length. The first branch of the radial artery (R 1 ) arises near the wing mark ( pterostigma ). The radial sector (Rs) comprises five independent branches, the medial vein (M) has four branches and is fused with the cubital vein (Cu) towards the base. The branching of the cubital wires Cu 1 and Cu 2 already takes place at the wing base. Shortly before its end, Cu 2 is strongly curved towards the outer edge of the forewing. The first anal vein (1A) has a single branch and meets the outer edge of the forewing in a curved manner. The second anal artery (2A) has six or more comb-shaped primary branches and a short transverse artery is located near the base of the wing. The hind wings are similar in size and veining to the forewings. They are 33.8 millimeters long and a maximum of 8.6 millimeters wide.
The abdomen is - as far as it is preserved - 26.5 millimeters long and consists of at least eight visible segments. However, the last abdomen are not preserved, so that the sex of the only almost completely preserved holotype is unknown.
The genus differs from others of the family Cimbrophlebiidae by the following features of its wing veins: the fact that the second anal vein (2A) has six or more comb-shaped primary branches distinguishes the genus from Perfecticimbrophlebia , which has only one branch with a distal bifurcation. Cimbrophlebia flabelliformis and Cimbrophlebia brooksi only have a maximum of four branches there. The fact that the second anal vein only has primary branches distinguishes the genus from Malmocimbrophlebia , Telobittacus , Cimbrophlebia leahyi , Cimbrophlebia westae and Cimbrophlebia bittaciformis , all of which have distally forked branches on the second anal vein.
Leaf mimesis and presumed way of life
The animals arranged their four wings and the abdomen in such a divergent way that the imaginary center point when these body parts were elongated was in the head area and these five "fingers" made them look very similar to the multi-limbed leaves of the ginkgo plant Yimaia capituliformis . In view of the fact that the first description only compared a single pair of fore and hind wings with a single leaf of Yimaia capituliformis and the fact that the wing surfaces are roughly structured like the leaves of several other species of Ginkgoales, the assignment is exactly this both species are unsure, although this reinforces the likelihood of leaf mimesis in these beaked flies .
There are two attempts to explain the reason for this sheet mimicry. The relatively large animals (recent representatives of the beaked flies have a wingspan of only approx. 50 millimeters) had to be much easier to detect for predators than other beaked flies that appeared at the same time. In addition, because of their unusually long and slender legs, they must have been bad runners and because of their weakly built wings they must also have been bad flyers, as are the relatives of the species still alive today. Because of their appearance in the leaves of the corresponding ginkgo plants, which represent around 12.4% of the fossil plant species found at the site, the animals could have occupied a suitable niche that is sufficiently safe from predators. The second explanation assumes that the animals with their appearance within the leaves of the ginkgo plants could well have pursued a predatory way of life. Although hardly any herbivorous animals have been found in the only species of Ginkgoales still in existence today, the Ginkgo ( Ginkgo biloba ), fossils of a variant of Yimaia capituliformis whose leaves were more fingered, could, however, have a higher proportion of insects than other Mesozoic plant groups - signs of corrosion can be detected. These insects may have been the food source of Juracimbrophlebia . The beaked flies and the ginkgo plants could have been in a mutualistic interrelation, in that the plant could have offered the enemy of its predators sufficient protection. This theory is confirmed by the fact that overlaps in the occurrence of other ginkgo plants with finger-shaped leaves and species of the Cimbrophlebiidae were found, although the similarity between Juracimbrophlebia and its suspected symbiotic plant remained unique.
Taxonomy and systematics
Since, with the exception of the holotype, essentially only wings have been preserved in the Juracimbrophlebia fossil material , Wang et al. to determine the probable relationship within the family Cimbrophlebiidae on the basis of the wing characteristics. The material was compared with that of five other taxa and an as yet undescribed species of the family Cimbrophlebiidae. On the basis of four autapomorphies - two comb-shaped and several other branches on vein 2A, long primary rest on 2A, and strongly curved vein 1A - three paraphyletic groups could be identified, but their relationships to one another could not be further determined. The three groups include the one, as yet undetermined species from the lower Toarcium , the clade Juracimbrophlebia + Malmocimbrophlebia , and the clade Cimbrophlebia + Telobittacus . The clade Juracimbrophlebia + Malmocimbrophlebia could not be further analyzed, mainly because of the poor fossil material of the latter genus, but the result regarding the third clade is only weakly based on a single autapomorphy. Ultimately, no monphylum above the level of the genus could be found during the investigation, but it has been shown that the branching of vein 2A changed from simple to complex in the course of the development of the groups.
The following cladogram results from the above considerations:
| Cimbrophlebiidae |
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Fossil material
The holotype (inventory number CNU-MEC-NN-2010-050P / C) has a well-preserved, almost complete body in which most of the four wings, not the wing tips, the genital area and parts of the antennae and legs have been preserved. Another four Paratype specimens are known, but they are far less well preserved. In two, for example, only a single fore wing is (partially) preserved, in another it is the overlapping wings, together with parts of the body and the antennae. All copies are in the collection of the "Key Laboratory of Insect Evolution and Environmental Changes" at Capital Normal University in Beijing.
supporting documents
Individual evidence
- ↑ a b c d e f g h Yongjie Wang, Conrad C. Labandeira; Chungkun Shih, Qiaoling Ding, Chen Wang, Yunyun Zhao & Dong Ren: Jurassic mimicry between a hangingfly and a ginkgo from China . In: Proceedings of the National Academy of Sciences . 109, No. 50, December 11, 2012.
- ↑ Mecoptera: scorpion flies. CSIRO, accessed September 30, 2013 .
- ↑ Yongjie Wang, Conrad C. Labandeira; Chungkun Shih, Qiaoling Ding, Chen Wang, Yunyun Zhao & Dong Ren: Jurassic mimicry between a hangingfly and a ginkgo from China: Supporting Information - SI Text . In: Proceedings of the National Academy of Sciences . 109, No. 50, December 11, 2012.