Palaeopsychops Douglasae

''Palaeopsychops'' is an extinct genus of lacewing in the moth lacewings family Ithonidae. The genus is known from Early Eocene fossils found in Europe, and North America and is composed of ten species. The ten species can be informally separated into two species groups based on veination of the forewings, the "European" and "North American" groups. When first described, the genus was placed in the family Psychopsidae, but later was moved to Polystoechotidae, which itself is now considered a subgroup of the moth lacewings.

Distribution & age

The European species of ''Palaeopsychops'' are all known from the Early Eocene Fur Formation along the western Limfjord coast of Denmark. Most of the thick formation is diatomites with an interspersed sequence of approximately 179 ash layers. Argon–argon radiometric dating of ash layer "+19", which is slightly lower in the strata then the "insect beds", has determined a age.

''Palaeopsychops'' species have been recovered from three locations in the Okanagan highlands, the Horsefly shales near Horsefly, British Columbia, the Coldwater Beds Quilchena site near Quilchena, British Columbia and the Klondike Mountain Formation in Republic, Washington, northern Ferry County, Washington. The Okanagan highlands are aged between for the Quilchena site to for the Klondike Mountain Formations Tom Thumb Tuff member.

Archibald and Makarkin (2006) suggested the Turgai Sea which separated western Europe and Asia from the Cretaceous to Oligocene prevented the spread of polystoechotid group lacewings into Asia from Europe. The disjunct distribution of ''Palaeopsychops'' between Denmark and the Okanagan highlands may have been enabled by rising crust elevations in the northern Atlantic region and subsequent increase in landmass during the Late Paleocene which linked Northern Europe with Greenland until at least the Early Eocene. Several land bridge routes may have acted as migration corridors for biotic interchange, the northern De Geer land bridge from Fennoscandia to North America via northern Greenland, and the southern Thulean land bridge from northern Britain though the Faroe Islands and then Greenland and North America. Other insect genera that share a similar disjunct distribution include the mecopteran ''Cimbrophlebia'', the green lacewing '' Protochrysa'' and the bull dog ant '' Ypresiomyrma''.

Paleoenvironment

The Fur formation represents a marine depositional environment of the inland water body which is ancestral to the North Sea. While the ancestral water body had an occasional opening to the Atlantic, it was entirely or almost entirely enclosed by land. The Fur formation outcrop is of a site that is an undetermined distance from the paleoshoreline with the preserved terrestrial flora and fauna suggested to have been carried from a shoreline to the north of the site by winds or drifting. Analysis of the δ¹⁸O/δ¹⁶O isotope ratio found in mollusc shells in the formation indicates paleotemperatures were of a low megathermal mean annual temperature, though the presence in the paleobiota of thermophilic taxa could indicate a lower mean annual temperature combined with a higher coldest month mean temperature.

All three Okanagan Highlands sites represent upland lake systems that were surrounded by a warm temperate ecosystem with nearby volcanism. The highlands likely had a mesic upper microthermal to lower mesothermal climate, in which winter temperatures rarely dropped low enough for snow, and which were seasonably equitable. The paleoforest surrounding the lakes have been described as precursors to the modern temperate broadleaf and mixed forests of Eastern North America and Eastern Asia. Based on the fossil biotas the lakes were higher and cooler then the coeval coastal forests preserved in the Puget Group and Chuckanut Formation of Western Washington, which are described as lowland tropical forest ecosystems. Estimates of the paleoelevation range between higher than the coastal forests. This is consistent with the paleoelevation estimates for the lake systems, which range between , which is similar to the modern elevation , but higher.

Estimates of the mean annual temperature have been derived from climate leaf analysis multivariate program (CLAMP) analysis of the Republic and Quilchena paleofloras, and leaf margin analysis (LMA) of all three paleofloras. The CLAMP results after multiple linear regressions for Republic gave a mean annual temperature of approximately , with the LMA giving . CLAMP results from Quilchena returned the higher which was supported by the returned from the LMA. LMA of the Horsefly flora returned a mean annual temperature of . These are lower than the mean annual temperature estimates given for the coastal Puget Group, which is estimated to have been between . The bioclimatic analysis for Republic, Quilchena, and Horsefly suggest mean annual precipitation amounts of and respectively.

History and classification

The genus was first described by Andersen (2001) from a series of 31 fore and hind wing part-counterpart fossils plus three partial body fossils found in the Fur Formation. Andersen chose the genus name as a combination of the psychopsid families nominal genus ''Psychops'', itself a combination of the Greek words ''psyche'' and ''opsis'' meaning "butterfly" and "appearance", with the Latin word ''palaeo'' meaning "old". Andersen designated ''Palaeopsychops latifasciatus'' as the type species, and named three other species in the same paper, ''Palaeopsychops abruptus'', ''Palaeopsychops angustifasciatus'', and ''Palaeopsychops maculatus''. Of the study material, the holotype specimens of all four species, along with paratypes for ''P. abruptus'' and '' P. angustifasciatus'' were deposited in the Geological Museum, University of Copenhagen. The four holotypes plus ''P. abruptus'' paratype 1 were all declared by Andersen as danekræ, specimens of high scientific value to the Danish. Additional paratype fossils were spread out between a number of collections including the Fur Museum on Fur Island, the Moler Museum on Mors Island and private collections in Nykøbing Mors Denmark and in Germany.

The fifth species, ''Palaeopsychops dodgeorum'', was described by Makarkin and Archibald (2003) two years later . The holotype hindwing was found at the Coldwater Beds

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