The systematics within the Aeshnida sensu Bechly 1996 is still under debate (Dijkstra et al. 2013) with two approaches being at issue. Von Ellenrieder (2002) used the taxon Aeshnidae Leach, 1815, for all extant species that could be found within the taxon Aeshnida Bechly, 1996, sensu Bechly (2001, 2003) that comprises multiple taxa on a family level. Von Ellenrieder's interpretation of the Aeshnidae is generally used, because it defines a group that is clearly a clade. Bechly’s approach, however, bears the opportunity for a practical way of recognizing the divisions within the clade. This is very useful, especially in the field of paleoentomology. Hence we follow the nomenclature proposed by Bechly (2003).
A phylogenetic analysis based on morphological characters of larvae and adults of extant species showed strong evidence for a sister-group relationship between the genera Gomphaeschna, Sarasaeschna, Oligoaeschna and Linaeschna and the remaining species (=Aeshnodea Bechly, 1996) (von Ellenrieder 2002).
The family Gomphaeschnidae Tillyard & Fraser, 1940 (sensu Bechly 1996 and Bechly et al. 2001), is at least of Lower Cretaceous age (Bechly et al. 2001) and comprises the subfamilies Gomphaeschnaoidinae Bechly et al. 2001 and Gomphaeschninae Tillyard & Fraser, 1940 (sensu Bechly et al. 2001) as well as some taxa that were not assigned to a subfamily.
List of all known fossil Gomphaeschnidae (sensu Bechly 1996, Bechly et al. 2001)
Not assigned:
Cretalloaeschna cliffordae Jarzembowski & Nel, 1996, from the Lower Cretaceous of England (Bechly et al. 2001);
Anglogomphaeschna eocenica Nel & Fleck, 2014, from the Late Eocene of the Isle of Wight; Sophoaeschna frigida Zhang et al., 2008, from Late Jurassic to Early Cretaceous of Inner Mongolia, China;
Falsisophoaeschna generalis Zhang et al., 2008, from Late Jurassic to Early Cretaceous of Inner Mongolia, China;
Gomphaeschnaoidinae:
Anomalaeschna berndschusteri Bechly et al., 2001, from the Lower Cretaceous of Brazil;
Cretagomphaeschnaoides jarzembowskae Zheng et al., 2016, from the Cretaceous of Myanmar;
Sinojagoria imperfecta Bechly et al., 2001, from the Lower Cretaceous of China (Liaoning);
Sinojagoria cancellosa Li et al., 2012, from the Upper Jurassic or Lower Cretaceous of China (Liaoning);
Sinojagoria magna Li et al., 2012, from the Upper Jurassic or Lower Cretaceous of China (Liaoning);
Paramorbaeschna araripensis Bechly et al., 2001, from the Lower Cretaceous of Brazil;
Progomphaeschnaoides ursulae Bechly et al., 2001, from the Lower Cretaceous of Brazil;
Progomphaeschnaoides staniczeki Bechly et al., 2001, from the Lower Cretaceous of Brazil;
Plesigomphaeschnaoides mongolensis Bechly et al., 2001, from the Lower Cretaceous of Mongolia;
Plesigomphaeschnaoides pindelskii Bechly et al., 2001, from the Lower Cretaceous of England;
Gomphaeschnaoides obliquus (Gomphaeschna obliqua) Wighton, 1987, from the Lower Cretaceous of Brazil (Bechly et al. 2001);
Gomphaeschnaoides magnus Bechly et al., 2001, from the Lower Cretaceous of Brazil;
Gomphaeschnaoides petersi Bechly et al., 2001, from the Lower Cretaceous of Brazil;
Gomphaeschnaoides betoreti Bechly et al., 2001, from the Lower Cretaceous of Brazil;
Gomphaeschninae:
? Oligoaeschna anglica Cockerell & Andrews, 1916, Upper Eocene, Isle of Wight (Nel & Fleck 2014; Nel et al. 2005);
Oligoaeschna needhami Cockerell, 1907, from the Lower Oligocene of Colorado (Nel et al. 1994b);
Oligoaeschna oligocenica Nel & Papazian, 1983, from the Lower Oligocene of France (Nel et al. 1994b);
Sarasaeschna (Oligoaeschna) pryeri Martin, 1909, from the Upper Pliocene of Japan (Esaki & Asahina 1957; Nel et al. 1994b);
Oligoaeschna conjuncta Martynov, 1929, from the Upper Oligocene of Kasakhstan (Nel et al. 1994b);
? Gomphaeschna inferna Pritykina, 1977, from the Lower Cretaceous of Russia (Buryatia);
? Gomphaeschna sibirica Bechly et al., 2001, from the Lower Cretaceous of Russia (Siberia);
Gomphaeschna miocenica Prokop & Nel, 2002, from the Lower Miocene of the Czech Republic;
? Gomphaeschna danica Madsen and Nel, 1997, from the Paleocene/Eocene of Denmark;
Gomphaeschna paleocenica Madsen and Nel, 1997, from the Paleocene/Eocene of Denmark;
Gomphaeschna schrankii Lewis, 1988, from the Paleocene of North Dakota.
Geological Setting. The active clay pit Schaßbach (46°47'53.32"N, 14°48'23.77"E) is located in eastern Carinthia about 3.8 km northwest of the historical town center of St. Andrä (District Wolfsberg). The site lies within an intramontane basin that was formed during late Early (Karpatian) and early Middle Miocene (Badenian) pull-apart phases (Reischenbacher & Sachsenhöfer 2013). The Koralpe restricts the basin on its eastern side, whereas the Saualpe is the western boundary of the basin.
The fine laminated mudstones (‘fish-shale’) that alternate with siltstones are referred to the lacustrine lower part of the Lower Badenian Mühldorf Formation (Reischenbacher et al. 2007; Reischenbacher & Sachsenhöfer 2013). The overlying marine sediments were dated to an age of 14.91 Ma (Reischenbacher et al. 2007). Harzhauser et al. (2015) suggested the name ‘Lake Lavant’ for the fossil lake.
Various plant fossils are known from the Schaßbach clay pit including Ginkgo adiantoides (Meller et al. 2015). Most of the plant remains come from siltstones without a continuous lamination. Plant fossils from fine laminated mudstones are way less common but show a more optimal kind of preservation. Vertebrate fossils so far include the very abundant cyprinid and gobiid fishes as well as rare skeletal bird remains. Also small down feathers are not uncommon in the biolaminites. Only one freshwater snail species (Harzhauser et al. 2015) and one terrestrial pulmonate species (Harzhauser pers. communication) are known up to the present.