Reassessment of the Dysagrionidae Taxon concepts based on the presence of accessory antenodal crossveins. The Dysagrioninae was originally proposed by Cockerell (1908a) as a subfamily of Agrionidae (Zygoptera), comprised of the two extinct genera Dysagrion and Phenacolestes. He distinguished it from other agrionids solely by the presence of accessory antenodal crossveins, i.e., in the costal space between Ax2 and the nodus: two in Dysagrion and three in Phenacolestes (P. mirandus Cockerell from the Priabonian shale of Florissant, Colorado was then its only confirmed species, Fig. 2). Calvert (1913) examined six specimens of P. mirandus, five of which had the antenodal region preserved, and found that three of these had three accessory antenodal crossveins, and the other two had two. He agreed with Campion (1913) that this variability made Cockerell���s Dysagrioninae untenable. Campion thought that P. mirandus most closely resembles the extant Neotropical Thaumatoneura McLachlan, which also has a variable number of accessory antenodal crossveins. Tillyard & Fraser (1939), Fraser (1957) and Nel & Paicheler (1994) did not recognise Cockerell���s Dysagrioninae, placing Phenacolestes in the Amphipterygidae (Tillyard & Fraser 1939) and Pseudolestidae (Thaumatoneurinae) (Fraser 1957; Nel & Paicheler 1994). Modern photographs clearly confirm the presence of three accessory antenodal crossveins in the holotype of P. mirandus (US National Parks Service website, see our drawing from this photograph, Fig. 2). Cockerell (1908a) also described a new species from Florissant as Phenacolestes ? parallelus Cockerell, a tentative member of the genus as the region of the diagnostic accessory antenodal crossveins is not preserved (University of Colorado: UCM 4503, part and counterpart). Subsequently discovered specimens confirmed that the species is a Phenacolestes: a proximal half of a wing (Yale Peabody Museum: YPM IP 220974) has four accessory antenodal crossveins (Cockerell 1908b) and a third, almost complete specimen (University of Colorado: UCM 4545), also from Florissant (Cockerell 1908c), has three in both forewings and three in both hind wings. Here, we figure these (Figs. 2, 3) as, to our knowledge, no specimen of the species has been previously illustrated other than by a poorquality photograph of UCM 4545 (Cockerell 1908c, his Fig. 4). The third species attributed to the genus, P. ? coloratus (Hagen) (mid-Miocene, Radoboj, Croatia) is poorly known, inadequately described, and we know of no published drawing or photograph (Hagen 1848; and see Nel & Paicheler 1994; Nel et al. 2005b). We treat it as a possible member of the genus (adding the question mark), family, and suborder pending examination of the specimen. The discussions of the above authors concerned the appropriateness of basing the taxon on a variable character state, i.e., two or three accessory antenodals in P. mirandus (the variability in P. parallelus described above was not known to them); the presence of two such crossveins in Dysagrion, however, was not doubted. Although Scudder���s original drawings should have established that this is not always the case, it remained unquestioned from the time of Cockerell���s works cited above to the present day. Scudder���s drawing of Dysagrion fredericii Scudder (Ypresian, Green River Formation, Wyoming) (1890: plate 6, Fig. 9) type specimen 4167/4168 (now MCZ numbers 381A, B) shows two accessory antenodal crossveins; however, there are none in his drawing (1890: plate 6, Fig. 3) of the type of D. packardii Scudder (Green River Formation, Wyoming) (Scudder cites the specimen as Packard number 146), a copy of which had already appeared in a work by Zittel (1885: Fig. 979) which Scudder edited. Tillyard & Fraser (1939: Fig. 3.1) provided a drawing of the wing (re-drawn from Scudder?), adding two accessory antenodal crossveins, which Fraser subsequently reproduced (1957: Fig. 34.1) (the specific epithet spelled ��� packardi ��� in both). Although Carpenter had the Museum of Comparative Zoology (MCZ) specimens available to him, his drawing of D. packardii (1992, his Fig. 52.1) included these presumptive accessory antenodal crossveins, by which he in part distinguished the genus. Bechly (1996) based his tribe Congqingiini (Congqingia Zhang and Petrolestes Cockerell) on its members lacking accessory antenodal crossveins, in contrast to his Dysagrionini (Dysagrion and Phenacolestes), reported to possess them as above. To resolve confusion as to the presence, and so the diagnostic usefulness, of accessory antenodal crossveins in Dysagrion species, considering the prominent role they have played in understanding their relationships at various taxonomic levels, we examined new, high resolution photographs of Scudder���s original Dysagrion specimens housed in the collections of the MCZ. The location of the holotype of D. packardii (Fig. 4C, re-drawn here from Scudder 1890, plate 6 Fig. 3) is unknown, but we were able to examine new photographs of cotype MCZ 4656 (Packard number 252) (Fig. 4A, B). In this specimen, the proximal portion of the antenodal region is missing, but the region where these crossveins should occur, if present, is reasonably well preserved. We did not detect any (either dry or wetted with ethanol), consistent with Scudder���s original description and contra subsequent authors. We also examined new photographs of the D. lakesii Scudder (Green River Formation, Wyoming) type specimen MCZ 4101 (Packard number 259, not previously illustrated) (Fig. 5); these also show no evidence of such accessory crossveins, which should be readily detectible if present. In the type of D. fredericii (Scudder���s number 4167/4168, now MCZ numbers 381A, B), we see one weakly preserved accessory crossvein, which we indicate by a dotted line in Fig. 6, but we doubt there are two, differing from Scudder���s drawing (1890) as discussed by Cockerell (1908a). Tillyard & Fraser (1939) and Fraser (1957: Fig. 34.2, spelled ��� frederici ���) subsequently reproduced Scudder���s drawing of this specimen with two accessory crossveins. We also examined photographs of MCZ 382, 1497, and 4147, but these fossils are fragmentary and do not possess this region. Cockerell and subsequent authors (as above) were then incorrect in asserting that the presence of accessory antenodal crossveins characterises Dysagrion and justifies its association with Phenacolestes. Seven genera have been subsequently associated with Dysagrion and Phenacolestes as forming the current Dysagrionidae: Primorilestes, Petrolestes, Congqingia, Electrophenacolestes Nel & Arillo, Burmadysagrion Zheng et al., Electrodysagrion, and Palaeodysagrion (we exclude the latter three, see below) (Figs. 7���9). None of these except Electrophenacolestes possess an accessory antenodal crossvein. None of the new species that we associate here with the family (below) possess them. A presence of accessory crossveins is not, therefore, a useful character state on which to base this family concept, define constituent subfamilies, nor characterise the genus Dysagrion. Subsequent definitions of Dysagrionidae. Some or all of the above genera and sometimes Thaumatoneura, Eodysagrion Rust et al., and others have been grouped in various family configurations, including in the Agrionidae, Amphipterygidae, Pseudolestidae, Megapodagrionidae, as subfamilies of Thaumatoneuridae (Dysagrioninae and Thaumatoneurinae: e.g., Bechly 1996; Nel et al. 2005 a, 2005b; Nel & Arillo 2006), or of the Dysagrionidae (Dysagrioninae, Thaumatoneurinae and Eodysagrioninae: Rust et al. 2008; Dysagrioninae, Burmadysagrioninae and Eodysagrioninae: Zheng et al. 2016a, 2016b, 2017; and independent of Thaumatoneura and Eodysagrion: Garrouste & Nel 2015; Nel et al. 2016; Huang et al. 2017). Bechly (1996) distinguished the taxon as Dysagrioninae (within Thaumatoneuridae: Dysagrion, Petrolestes, Phenacolestes and Congqingia) by quadrangle shape as its single defining trait, although he did not describe this, and noted that it is also present in Sieblosiidae. Nel & Arillo (2006) agreed, further distinguishing it by the combination of: antesubnodal space without crossveins; absence of the oblique vein O; CuA���A space very broad; the base of IR2 positioned proximal to the nodus; RP3-4 arising between the arculus and nodus closer to nodus; and the base of RP2 being in a very distal position. Nel & Fleck (2014) closely followed this definition. Rust et al. (2008) erected the Eodysagrioninae for Eodysagrion as an equal rank taxon with Dysagrioninae and Thaumatoneurinae within the Dysagrionidae. The Dysagrionidae is currently not considered to be close to the Thaumatoneuridae. Garrouste & Nel (2015) questioned a close relationship between them because of inconsistencies in positions of the nodus and bases of branches of RP and IR2, the difference in shape of their quadrangles and of their leg spines and thoracic skewedness, and as an incomplete interpleural suture is present in Petrolestes, but it is complete in Thaumatoneura. They further suggested that Dysagrionidae might not even belong in the Zygoptera. Huang et al. (2017) explicitly separated them, elevating Dysagrioninae and Thaumatoneurinae to family level. They rejected their putative synapomorphies of costal margin curvature and lack of crossveins in the antesubnodal space as weakly supported and most likely convergent, also discussing their difference in quadrangle shape. They further considered Eodysagrion as a provisional member of the Thaumatoneuridae, among their reasons further stressing the importance of quadrangle shape, which is rectangular in Eodysagrion like that of Thaumatoneura, not Dysagrionidae. Subfamilies of Dysagrionidae. Huang et al. (2017), in elevating the Dysagrioninae to family status, also elevat- ed the former tribes Petrolestini and Dysagrionini to subfamilies: Petrolestinae, comprised of Petrolestes (P. hendersoni Cockerell: Ypresian Green River Formation, Colorado, United States of America; P. messelensis Garrouste & Nel: Lutetian, Grube Messel, Germany) and Congqingia (C. rhora, Aptian, i.e., Early Cretaceous, Laiyang Formation, Shandong, China; recent age estimate: Zhou et al. 2020) (Fig. 8); and their revised concept of Dysagrioninae, comprised of Dysagrion, Phenacolestes, Primorilestes (P. violetae Nel et al.: Priabonian, Bolshaya Svetlovodnaya (Biamo), Primorye, Russia; P. madseni Rust et al.: earliest Ypresian Fur Formation, Denmark; P. magnificus Nel et al.: Miocene, Satovcha Graben, Sivik Formation, Bulgaria), and Electrophenacolestes (E. serafini: Priabonian, Baltic amber, Poland) (Fig. 7). Bechly (1996) separated these (as tribes) by Petrolestinae having: 1, no accessory antenodal crossveins; 2, IR1 shortened and strongly zigzagged; and 3, the bases of RP3-4 and IR2 situated midway between nodus and arculus [Dysagrioninae: origin of RP 3-4 in middle third between arculus and nodus, usually at about two-thirds the distance; IR2 originates at or very near subnodus]. However, character state 1 is, as above, variable and not informative. Nel et al. (2005b) rejected character state 2, as this region is not preserved in the type species Petrolestes hendersoni and is not consistent in other specimens. Character state 3 is the sole trait separating these taxa. In the Dysagrioninae the origin of RP3-4 is in the middle third between the arculus and nodus, usually at about two-thirds of the distance, and IR2 originates at or very near the subnodus. In the Petrolestinae, the origin of RP3-4 is more proximally positioned, closer to or at the point midway between the arculus and subnodus, and IR2 originates close to or on RP3-4. There are no currently recognised taxa of tribe-level rank of the Dysagrionidae. Emended diagnosis of the Dysagrionidae. The wings of Dysagrionidae are easily separated from those of other Cephalozygoptera and tentative Cephalozygoptera (new suborder, see below) by a combination of: 1- oblique crossvein O absent [Sieblosiidae: present]; 2- arculus at or immediately proximal to Ax2 [Whetwhetaksidae: nearer to Ax1]. They are distinguished from similar appearing Zygoptera by a combination of the above and the following character states 3���9 of the wings, slightly amended from the diagnoses of Nel & Arillo (2006) and Nel & Fleck (2014), and 10, of the head: 3- quadrangle broad, distal side longer than proximal side, posterior side longer than anterior, distal-posterior angle oblique, proximal-anterior angle usually about 90��; 4- nodus positioned at least a quarter wing length, usually more; 5- anterior anal vein separates from posterior anal vein briefly before joining CuP (i. e., is briefly free distal to petiole); 6- RP3-4 originating roughly between one third to two thirds length from arculus to subnodus, usually about two thirds (Primorilestes violetae furthest, just distal to middle third, but P. madseni within middle third); 7- antesubnodal space without crossveins; 8- CuA���A space expanded in middle to at least two cells wide, often more; 9- CuA long, terminating on posterior margin at mid-wing or longer (termination most proximal in Primorilestes species, but there mid-wing); 10- head width across eyes about twice the length from anterior margin of antefrons to posterior of occiput; compound eyes more or less adpressed to the head capsule, convex laterally but not spherical, posterolateral corners extended posteriorly to varying degrees, sometimes even acutely; distance between compound eyes at level of centre of ocelli about one eye���s width or less; head not distinctly extended laterally with bulging, spherical compound eyes as in Zygoptera (i.e., not ���hammerhead��� or ���dumbbell��� shaped). We agree with Nel & Arillo (2006), Nel & Fleck (2014), and Garrouste & Nel (2019) that an expanded CuA���A space is characteristic of the Dysagrionidae (character state 8). These character states associate Dysagrion, Phenacolestes, Primorilestes, Petrolestes, Electrophenacolestes, and Congqingia in agreement with previous authors, as well as Furagrion Petrulevičius et al. (restored, below); the new genera described here, Okanagrion, Okanopteryx and Stenodiafanus; and species of the new collective genus Dysagrioninites. They exclude Electrodysagrion, Palaeodysagrion and Burmadysagrion (see below). We tentatively include the Thanetian (late Paleocene: see age discussed by Wedmann et al. 2018) Valerea Garrouste et al. (one species: V. multicellulata, Menat Formation, France) for reasons discussed below. We include Furagrion in the Dysagrionidae and treat Valerea as a tentative member. Henriksen (1922) originally described Furagrion jutlandicus (Henriksen) from the early Ypresian Fur Formation of Denmark (���Mo-Clay���) as a species of Phenacolestes, and therefore a member of Cockerell���s Dysagrioninae. He based it on a specimen with three partial wings and part of the abdomen. None of these wings are preserved proximal to the nodus, and although they then lack the quadrangle and antenodal space, he associated the species with Phenacolestes by shared character states of the preserved portion. Owing to the lack of the proximal wing characters, Nel & Paicheler (1994) treated the species as ��� Phenacolestes ��� jutlandicus of indeterminate family. Rust (1999) reported a new, almost complete wing which he called ��� Dysagrioninae gen. indet. jutlandicus ���. Petrulevičius et al. (2008) revised the species based on this fossil, erecting the monotypic genus Furagrion for it. They assigned it to the Megapodagrionidae, finding an association with the Dysagrionidae unlikely by the lack of a distinct broadening of the antenodal area at the level of Ax1 and Ax2, and the distal side of the quadrangle not distinctly longer than the proximal. However, the amount of broadening of the antenodal area is variable in the family, and is in some species quite slight, and so this character state does not have clear diagnostic value in distinguishing it; in Furagrion it is comparable with that of Electrophenacolestes. While the distal side of the quadrangle of Furagrion is not much longer than the proximal side as it is in many dysagrionids, it is still longer, like that of Congqingia (Fig. 8). Furagrion then satisfies all wing character states of the diagnosis provided above, and so we restore it to the Dysagrionidae. Zessin (2011) described a second species of the genus, F. morsi Zessin, based on the proximal half of a wing. Although the enigmatic Thanetian Valerea multicellulata (Fig. 9) is known from a single, fragmentary wing in which only character state 1 of our family definition is determinable, we tentatively associate it with the Dysagrionidae by its otherwise notable similarity with the new genus Okanagrion with which it shares distinctive character states, some not otherwise known in the Odonata (see below, in the discussion of Okanagrion and support by our cladistic analysis). The Alaskan Chickaloon specimen and ��� Megapodagrionidae ��� genus and species A are probably dysagrionids; Thanetophilosina Nel et al. and NHMUK I.9866/I.9718 could be dysagrionids. We agree with Garrouste & Nel (2019) that the fragmentary specimen from the Thanetian or Ypresian Chickaloon Formation of Alaska (unnamed) is likely a dysagrionid by its density of veins and long CuA with an expanded CuA���A space up to four cells deep (Fig. 9). Its preserved portion only possesses character states 1, 8 and 9 of the Dysagrionidae diagnosis, and so we treat it here as a probable member of the family. Similarly, the partial wing ��� Megapodagrionidae ��� genus and species A of Petrulevičius et al. (2008) from the early Lutetian of Grube Messel, Germany, shares character states 1, 8 and 9 of the Dysagrionidae diagnosis with the Chickaloon specimen, and is more complete than it, with the apical portion present and well-preserved. Petrulevičius et al. (2008) discuss various possible family associations and only tentatively assign it to the Megapodagrionidae, noting that as then constituted, that family could not be defined by any known synapomorphies of wing venation. The Megapodagrionidae, long considered to be polyphyletic, has since been separated into a number of families based on a revised molecular phylogeny (Dijkstra et al. 2014). We treat this fossil as also probab, Published as part of Archibald, Bruce, Cannings, Robert A., Erickson, Robert J., Bybee, Seth M. & Mathewes, Rolf W., 2021, The Cephalozygoptera, a new, extinct suborder of Odonata with new taxa from the early Eocene Okanagan Highlands, western North America, pp. 1-133 in Zootaxa 4934 (1) on pages 8-27, DOI: 10.11646/zootaxa.4934.1.1, http://zenodo.org/record/4558796, {"references":["Cockerell, T. D. A. (1908 a) Fossil insects from Florissant, Colorado. Bulletin of the American Museum of Natural History, 24, 59 - 69, 1 pl.","Calvert, P. P. (1913) The fossil Odonate Phenacolestes, with a discussion of the venation of the legion Podagrion Selys. Proceedings of the Academy of Natural Sciences of Philadelphia, 65: 225 - 272.","Campion, H. (1913) The Antenodal Reticulation of the Wings of Agrionine Dragonflies. Proceedings of the Academy of Natural Sciences of Philadelphia, 65, 220 - 224.","Tillyard, R. J. & Fraser, F. C. (1939) A reclassification of the order Odonata based on some new interpretations of the dragonfly wing by R. J. Tillyard, continuation thereof by F. C. Fraser, Part II, the suborder Zygoptera (continued), Protanisoptera. Australian Zoologist, 9, 195 - 221.","Fraser, F. C. (1957) A reclassification of the order Odonata, Based on Some New Interpretations of the Venation of the Dragonfly Wing By the late R. J. Tillyard and F. C. Fraser, Revision. Royal Zoological Society of New South Wales, Sydney, 133 pp.","Nel, A. & Paicheler, J. - C. (1994) Les Lestoidea (Odonata, Zygoptera) fossiles: Un inventaire critique. Annales de Paleontologie, 80, 1 - 59.","Cockerell, T. D. A. (1908 b) Descriptions of Tertiary Insects IV. American Journal of Science, 26, 69 - 75. https: // doi. org / 10.2475 / ajs. s 4 - 26.151.69","Cockerell, T. D. A. (1908 c) Some Results of the Florissant Expedition of 1908. The American Naturalist, 42, 569 - 581. https: // doi. org / 10.1086 / 278976","Hagen, H. (1848) Die fossilen Libellen Europa's. Entomologische Zeitung, 9, 6 - 13.","Nel, A., Petrulevicius J. F. & Jarzembowsk, E. A. (2005 b) New fossil Odonata from the European Cenozoic (Insecta: Odonata: Thaumatoneuridae, Aeshnidae,? Idionychidae, Libellulidae). Neues Jahrbuch fur Geologie und Palaontologie, Abhandlungen, 235, 343 - 380.","Zittel, K. A. (1885) Classe Insecta. Insecten (Scudder, S. H. Ed.) In: Handbuch der Palaeontologie. Vol. 1. Abtheilung Palaeozoologie, Band 2, Mollusca and Arthropoda, R. Oldenbourg, Munchen and Liepzig, pp. 747 - 831.","Bechly, G. (1996) Morphologische Untersuchungen am Flugelgeader der rezenten Libellen und deren Stammgruppenvertreter (Insecta; Pterygota; Odonata) unter besonderer Beruchsichtigung der Phylogenetischen Systematik und des Grundplanes der Odonata. Petalura, Boblingen, Special Volume, 2, 1 - 402.","Scudder, S. H. (1890) The Tertiary insects of North America. Report of the United States Geological Survey of the Territories, 13, 1 - 734, 28 pls. https: // doi. org / 10.5962 / bhl. title. 44698","Petrulevicius, J. F., Wappler, T., Wedmann, S., Rust, J. & Nel, A. (2008) New Megapodagrionid Damselflies (Odonata: Zygop- tera) from the Paleogene of Europe. Journal of Paleontology, 82, 1173 - 1181. https: // doi. org / 10.1666 / 07 - 091.1","Rust, J, Petrulevicius, J. F. & Nel, A. (2008) The first damselflies from the lowermost Eocene of Denmark, with a description of a new subfamily (Odonata, Zygoptera, Dysagrionidae). Palaeontology, 51, 709 - 713. https: // doi. org / 10.1111 / j. 1475 - 4983.2008.00780. x","Nel, A., Simov, N., Bozukov, V. & Marinov, M. (2016) New dragonflies and damselflies from Middle Miocene deposits in SW Bulgaria (Insecta: Odonata). Palaeontologia Electronica, 19.3.35 A, 1 - 13. https: // doi. org / 10.26879 / 642","Nel, A. & Arillo, A. (2006) The first Baltic amber dysagrionine damselfly (Odonata: Zygoptera: Thaumatoneuridae: Dysagrioninae), Annales de la Societe entomologique de France, New Series, International Journal of Entomology, 42, 179 - 182. https: // doi. org / 10.1080 / 00379271.2006.10700621","Nel, A., Petrulevicius, J. F., Gentilini, G. & Martinez-Delclos, X. (2005 a) Phylogenetic analysis of the Cenozoic family Sieblo- siidae (Insecta: Odonata), with description of new taxa from Russia, Italy and France. Geobios, 38, 219 - 233. https: // doi. org / 10.1016 / j. geobios. 2003.10.007","Zheng, D. Wang, B. Jarzembowski, E. A. Chang, S. - C. & Nel, A. (2016 a) Burmadysagrioninae, a new subfamily (Odonata: Zygoptera: Dysagrionidae) from mid-Cretaceous Burmese amber. Cretaceous Research, 67, 126 - 132. https: // doi. org / 10.1016 / j. cretres. 2016.07.006","Zheng, D., Zhang, Q., Nel, A., Jarzembowski, E. A., Zhou, Z., Chang, S. - C. & Wang, B. (2016 b) New damselflies (Odonata: Zygoptera: Hemiphlebiidae, Dysagrionidae) from mid-Cretaceous Burmese amber. Alcheringa, 41, 12 - 21. https: // doi. org / 10.1080 / 03115518.2016.1164402","Zheng, D., Chang, S. - C., Nel, A., Jarzembowski, E. A., Zhuo, D. & Wang, B. (2017) Electrodysagrion lini gen. et sp. nov., the oldest Dysagrionini (Odonata: Zygoptera: Dysagrionidae) from mid-Cretaceous Burmese amber. Cretaceous Research, 77, 44 - 48. https: // doi. org / 10.1016 / j. cretres. 2017.05.008","Garrouste, R. & Nel, A. (2015) New Eocene damselflies and the first Cenozoic damseldragonfly of the isophlebiopteran lineage (Insecta: Odonata). Zootaxa, 4028 (3), 354 - 366. https: // doi. org / 10.11646 / zootaxa. 4028.3.2","Huang, D., Azar, D., Cai, C., Maksoud S., Nel, A. & Bechly, G. (2017) Mesomegaloprepidae, a remarkable new damselfly family (Odonata: Zygoptera) from mid-Cretaceous Burmese amber. Cretaceous Research, 73, 1 - 13. https: // doi. org / 10.1016 / j. cretres. 2017.01.003","Nel, A. & Fleck, G. (2014) Dragonflies and damselflies (Insecta: Odonata) from the Late Eocene of the Isle of Wight. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, 104, 283 - 306. https: // doi. org / 10.1017 / S 175569101400005 X","Zhou, J. - B., Han, W., Song, M. - C. & Li, L. (2020) Zircon U-Pb ages of the cetaceous [sic] sedimentary rocks in the Laiyang Basin, eastern China and their tectonic implications. Journal of Asian Earth Sciences. [early issue] https: // doi. org / 10.1016 / j. jseaes. 2019.103956","Garrouste, R. & Nel, A. (2019) Alaskan Palaeogene insects: a challenge for a better knowledge of the Beringian ' route' (Odonata: Aeshnidae, Dysagrionidae). Journal of Systematic Palaeontology, 17, 1939 - 1946. https: // doi. org / 10.1080 / 14772019.2019.1572235","Wedmann, S., Uhl, D., Lehmann, T., Garrouste, R. Nel, A., Gomez, B., Smith, K. & Schaal, S. F. K. (2018) The Konservat-Lagerstatte Menat (Paleocene; France) - an overview and new insights. Geologica Acta, 16, 189 - 213.","Henriksen, K. A. (1922) Eocene insects of Denmark. Danmarks Geologiske UndersOgelse, 2 raekke 37, 1 - 36.","Rust, J. (1999) Biologie der Insekten aus dem altesten Tertiar Nordeuropas. Habilitationsschrift zur Erlangung der venia legendi fur das Fach Zoologie. Postdoctoral thesis, Biologische Fakultat der Georg-August-Universitat Gottingen, Gottingen, Lower Saxony, 482 pp.","Zessin, W. (2011) Neue Insekten aus dem Moler (Palaozan / Eozan) von Danemark Teil 1 (Odonata: Epallagidae, Megapodagrioniidae). Virgo, Mitteilungsblatt des Entomologischen Vereins Mecklenburg, 14, 63 - 73.","Zhang, J. - F. (1992) Congqingia rhora gen. nov., spec. nov. - a new dragonfly from the Upper Jurassic of eastern China (Anisozygoptera, Congquingiidae fam. nov.). Odonatologica, 21, 375 - 383.","Dijkstra, K. - D. B., Kalkman, V. J., Dow, R. A., Stokvis, F. R. & van Tol, J. (2014) Redefining the damselfly families: the first comprehensive molecular phylogeny of Zygoptera (Odonata). Systematic Entomology, 39, 68 - 96. https: // doi. org / 10.1111 / syen. 12035","Garrouste, R., Wedmann, S., Pouillon, J. - M. & Nel, A. (2017) The oldest ' amphipterygid' damselfly of tropical affinities in the Paleocene of Menat (Zygoptera: Eucaloptera). Historical Biology, 29, 818 - 821. https: // doi. org / 10.1080 / 08912963.2016.1247448","Nel, A., Martinez-Delclos, X., Papier, F. & Oudard, J. (1997) New Tertiary fossil Odonata from France. (Sieblosiidae, Lestidae, Coenagrioniidae, Megapodagrionidae, Libellulidae). Deutsche Entomologische Zeitschrift, 44, 231 - 258. https: // doi. org / 10.1002 / mmnd. 19970440210","Zheng, D, Chang, S. - C. & Wang, B. (2018) A new dysagrionid damselfly (Odonata: Zygoptera: Palaeodysagrion) from mid- Cretaceous Burmese amber. Alcheringa, 42, 300 - 304. https: // doi. org / 10.1080 / 03115518.2017.1381991","Zheng, D., Zhang, Q., Nel, A., Jarzembowski, E. A. & Wang, B. (2019) Electrodysagrion neli sp. nov., the second Cretaceous dysagrionine damselfly (Odonata: Zygoptera: Dysagrionidae) from Kachin amber, northern Myanmar. Palaeoentomology, 2, 556 - 559. https: // doi. org / 10.11646 / palaeoentomology. 2.6.2","Cockerell, T. D. A. (1927) A new fossil dragonfly from the Eocene of Colorado. The Entomologist, 60, 81 - 82.","Rehn, A. C. (2003) Phylogenetic analysis of higher-level relationships of Odonata. Systematic Entomology, 28, 181 - 239. https: // doi. org / 10.1046 / j. 1365 - 3113.2003.00210. x","Garrison, R. W., von Ellenrieder, N. & Louton, J. A. (2010) Damselfly genera of the New World: an illustrated and annotated key to the Zygoptera. Johns Hopkins University Press, Baltimore, 490 pp.","Garrison, R. W., von Ellenrieder, N. & Louton, J. A. (2006) Dragonfly genera of the New World: an illustrated and annotated key to the Anisoptera. Johns Hopkins University Press, Baltimore, Maryland, 368 pp.","Tillyard, R. J. & Fraser, F. C. (1940) A reclassification of the order Odonata based on some new interpretations of the dragonfly wing by R. J. Tillyard, continuation thereof by F. C. Fraser, Part III, suborder Anisozygoptera. Australian Zoologist, 9, 359 - 396.","Hagen, H. (1858) Zwei Libellen aus der Braunkohle von Sieblos. Paleontographica, 5, 121 - 124.","Huang, D., Fu, Y. & Nel, A. (2019) The first amber stenophlebiid damsel-dragonfly (Odonata, Epiproctophora, Stenophlebiidae) from mid-Cretaceous amber of northern Myanmar. Cretaceous Research, 94, 40 - 44. https: // doi. org / 10.1016 / j. cretres. 2018.10.008"]}