AMNH LC-D4: A small piece containing very fine, filamentous hyphae with a very uniform thickness ca. 2–3 µm (fig. 3A–C). Most hyphal strands are sinuous and straight, some squiggly. The hyphae are very webby and possibly interconnecting (their density makes it difficult to tell), but they definitely branch. The hyphae grew on a dark mass of substrate that is partially preserved near the surface of the amber piece, with a dark reddish “halo” over the surface of the substrate and most hyphae (indicating some pyritization and/or oxidation). This substrate may be bark, since there are fragments of discernable bark fibers nearby (fig. 4A–C). Interestingly, the hyphae appear to have been growing into the fresher, lighter-yellow resin, since the fine, delicate filaments are perfectly arranged and undisturbed by any flow.

The filaments do not appear to be sheathed bacteria, since their cores do not appear to have cell chains. Sheathed bacteria are reported to occur in amber (Schmidt and Schäfer, 2005; Girard et al., 2009), although various lines of other data led Speranza et al. (2015) to conclude that these reports are instead of fungal hyphae. Saint Martin and Saint Martin (2017) disputed the interpretation of hyphae, even though Speranza et al. (2015) used confocal laser microscopy to detect the diagnostic presence of chitin polysaccharides, which occur in fungi but not bacteria. The filaments in Chickaloon amber are very similar to the webby hyphae of certain resinicolous ascomycetes that thrive on conifers, Mycocaliciales, which are known from the present through the Cenozoic (Tuovila et al., 2013). The genus Chaeonthecopsis, for example, is known from the Eocene (Baltic amber), the Oligocene (Bitterfeld amber), to the Recent; even the diagnostic capitulum and long stipe of the fossil ascomata are preserved in some of the fossils (Tuovila et al., 2013). No ascomata parts are preserved in the Chickaloon amber.

AMNH GC-A8: The specimen consists of roughly five clusters of fungal filaments attached to a dark, dense substrate that is probably a portion of a twig or other plant fragment (figs. 3D–G; 10A). Each filament is heavily melanized, multiseptate, linear, with 12 or fewer cells, approximately 10–15 µm thick and less than 100 µm in length. Tips are slightly narrower than the bases, and in longer strands there is a well-developed constriction between the apical and penultimate, or the penultimate and antepenultimate, cells; the apical or penultimate cells are enlarged in most conidia. Otherwise, there is little constriction between other cells. Some isolated conidia are floating free in the amber next to the clusters attached to substrate. We are grateful to Elina Kettunen (University of Helsinki) and Alexander Schmidt (University of Göttingen), who inform us that the fungus is a dematiaceous hyphomycete with multiseptate phragmaconidia. Though it bears some resemblance to sooty molds (Capnodiales), AMNH GC-A8 does not appear to belong to this group. One extant family of sooty mold, Metacapnodiaceae, comprises most of the fossil record of the group, which occur as fossils exclusively in amber from the upper part of the Early Cretaceous to the Miocene (Schmidt et al., 2014). Sooty molds are epiphytic ascomycetes with dark, flocculent hyphae (hence the name); they grow abundantly on sugar-rich secretions such as plant saps and honeydew excreted by sternorrhynchans (scale insects and aphids), the latter of which are abundant in the Chickaloon amber. AMNH GC-A8 differs from sooty molds by lacking moniliform (beadlike) conidia, but instead more closely resembles conidia of Casparytorula spp., a hyphomycete known from Eocene Baltic and Oligocene Bitterfeld ambers (Kettunen et al., 2015) (A. Schmidt, personal commun, to D.A.G., February 2018).

AMNH WH-2: Bryophyta: Musci (mosses). A piece containing two small microphyll “leaves” and clumps of spores, some of the latter within or bursting from membranous sacs (figs. 4D–F). Both microphylls have a thick midrib but lack veins; the epidermis appears to be one cell thick, the midrib is composed of several cell layers. The largest microphyll is 620 µm at its widest point, the midrib width 80 µm (microphyll length is unknown since the bases of both are not preserved). Apex of the larger microphyll is much less tapered, its margins with somewhat irregular serrations ca. 30–40 µm long, alternating with much smaller serrations (fig. 10C, D). Serrations of the smaller microphyll are more uniform and less dentate. Damage at the base of the larger microphyll does not appear to be feeding damage, such as from an insect, since the margins of the breaks correspond to the cell walls, as if the microphyll dried and fragmented.

The spores are generally associated with very thin, transparent, membranous, ovoid sacs, which are not cellular at 400× magnification; the sacs appear to occur in two size classes: the smaller class ranging from 150 × 90 µm to 220 × 110 µm (among the ones that were measured), and the larger ones 280 × 160 µm to 320 × 220 µm. Smaller sacs that are empty have a small hole at one or both ends; the larger sacs have a large hole in the middle (fig. 10B). Some sacs are completely empty; some have a small amount of unidentifiable granular material (probably degraded spores); others are replete with obvious spores. Spores are ovoid, size appearing the same between the two sizes of sacs, all spores ca. 5 µm in length and 3 µm width, with a longitudinal sulcus partially down the middle of some of the better-preserved and observable ones, like a coffee bean. Some clumps of spores are not associated with a sac, which presumably degraded. For two discrete clumps that were examined there were 98 and 120 spores. The spores are very small for bryophytes; this and the distinctive, membranous sacs suggest that they originated from another plant (or possibly a fungus), and their preservation with microphylls is coincidental.

Mosses have a fossil record that extend to the Carboniferous (Hübers and Kerp, 2012), and by the Cretaceous many modern families had appeared, including many taxa in Cretaceous amber (Bell and York, 2007; Katagiri et al., 2013; Hedenäs et al., 2014; Ignatov et al., 2016) and in Eocene Baltic and Miocene Dominican amber (e.g., ; Frahm and Newton, 2005; Heinrichs et al., 2014 many apparently belonging to epiphytic taxa. The microphyll structure resembles that of the living moss genus Thamnobrym (N. Cleavitt, personal commun. to C.J.W., March 2018).

AMNH WH-6: A small piece containing most of the remains of an oribatid mite, similar in overall structure to the family Damaeidae (fig. 11 A), which consists of fewer than 100 living species in 14 genera, primarily as mycophagous and algophagous inhabitants of leaf litter and subcortical microhabitats of temperate and boreal forests. Damaeidae occur in Eocene amber from the Baltic region and Rovno, Ukraine (Weitschat and Wichard, 2010; Perkovsky et al., 2010). The mite is near the corner of the amber piece, with the appendages of one side lost or completely obscured; the piece also contains dark layers from various resin flows as well as particulate plant matter. Body length (without appendages) is approximately 400 µm, with a slight constriction between the prodorsum and notogaster; legs are long and slender, length of the longest is 550 µm. The mite is dark and opaque, generally obscuring many of the setae, sensilia, and cuticular details except those visible at margins. Anterior-most appendage (pedipalps) (only one of a pair observable), with three short, stout podites, apical one pointed, with two long, fine solenidia. A pair of long, stiff solenidia occurs at the anterior end of the prodorsum. Structure of the legs is very distinctive and quite similar to that of the living family Damaeidae, in particular the “moniliform” legs (although this habitus also occurs in oribatid superfamilies closely related to Damaeoidea). Leg I has bulbous portions of the femur, genu, tibia, and at the base of the tela + basitarsus. The only bulbous portion of leg II is on what is either the genu or tibia (boundaries between podites are barely visible). The apices of tibiae in legs II and III each have a long, stiff solenidium that is nearly equal in length to that of its respective podite. Pretarsal claws are long, slender, and sickle shaped.

AMNH LC-D1: A piece of amber containing a complete mite (∼280 µm body length), which is moderately well preserved (fig. 5H). Cuticle of the notogaster and prodorsum is cracked and slightly disintegrated, precluding observation of most of the chaetotaxy, glands, and sensilia, though a pair of thick, plumose trichobothria/bothridial setae is visible, one at each posterolateral corner of the prodorsum. While identification of the mite in the Oribatida is certain, a more detailed identification will be challenging. The mite is rather generalized in structure, lacking specialized (e.g., plumose) setae and obvious cuticular microstructure (e.g., reticulations). The gnathosoma is well integrated and conical, laterally with a pair of projecting solenidia; legs are relatively short, pair I with an elongate solenidium dorsoapically on what appears to be the genu; all pretarsal claws are long, slender, and hooked.

The Oribatida is a highly diverse, speciose group of mites comprised of some 9000 living species in 172 families, largely inhabitants of soils, leaf litter, and moss (Norton and Behan-Pelletier, 2009). The fossil record of the group is ancient and diverse, beginning with unambiguous cuticular remains from the Devonian that are preserved in microscopic detail (Norton et al., 1988). Oribatids have even been implicated in the processing of plant detritus from Carboniferous swamps (Labandeira et al., 1997). Their fossil record in amber from the Cretaceous and Cenozoic is excellent (Dunlop et al., 2018). This is due partly to the improved techniques in preparation and high-magnification (400–1000x) microscopy (Sidorchuk, 2013), and the discovery of major new amber deposits. Taxa described more than a century ago in Eocene Baltic amber are being redescribed in great detail (e.g., Norton, 2000; Sidorchuk and Norton, 2010, 2011), which establish a new standard for study.

AMNH GC-A8: An amber piece containing most of a small (∼0.90 mm long) pseudoscorpion. The specimen is rather poorly preserved, the anterior portion lost at one surface of the amber, and most of the appendages on the left side are either lost or obscured among cracks in the amber. The body contents and cuticle are black and opaque, obscuring trichobothria, which are critical to identification of pseudoscorpions; eyes are not observable. The right pedipalp is mostly preserved, revealing a relatively long femur and short tibia (typical of pseudoscorpions), and most of the chela. Leg I is very slender (possibly preservational); leg II is best preserved, showing that the patella, tibia, and metatarsus are nearly equal in length; tarsus of leg IV is relatively stout. More distinctive is the long, slender body shape, which may be partly preservational but not entirely. Six opisthosoma segments are visible (of the typical 12); in many pseudoscorpions the opisthosoma is half this length or even less.

Like mites and spiders, Pseudoscorpionida is an ancient group that extends to at least the Middle Devonian (Schawaller et al., 1991). Their fossil record is not nearly as extensive as that of spiders and mites, however, owing to their lesser abundance and preferences for concealed microhabitats (e.g., subcortical, under stones, in leaf litter). The fossil record consists of 46 species in 16 families (primarily in Cenozoic and Cretaceous amber), reviewed by Harms and Dunlop (2017), who report a bias in the fossilization of families that live under bark. Interestingly, no extinct families are known from the Cretaceous, which may just reflect antiquity of the group. Eocene Baltic amber is the most diverse source of described pseudoscorpions, some of which show Mediterranean and African connections, even Gondwanan distributions (e.g., Feaellidae). Prior to discovery of the Chickaloon amber specimen the most northerly records of fossil pseudoscorpions were in Baltic amber and Late Cretaceous amber from Grassy Lake, southern Alberta, Canada. The specimen reported here extends the northernmost fossil occurrence by approximately 10° N paleolatitude.

Three pieces contain the remains of spiders, none of which could be identified to family level. AMNH WH-3B is a small (0.80 mm body length), complete juvenile lying next to a male chironomid, the cuticle of which is mostly cleared but with some decayed internal tissue visible (fig. 7D). AMNH LC-D7 (0.84 mm) is a different taxon, having considerably longer legs, which are folded and cover the ventral surface of the cephalothorax (fig. 5F). The entire dorsum and a portion of the anterior end of the spider are obscured by a dark mass; the opisthosoma is shriveled. AMNH LC-B3a, b is in two sections (A, B), both from the same piece, each containing a distinctive mesh of fibers that form a rounded structure some 5 mm in diameter (figs. 5A–E). The individual, fine strands are uniform in thickness, many of them woven and cabled into thick fibers, all interconnected into a mesh lying in several concentric layers. The interior of the rounded structure is empty. This is clearly the silken cocoon of a terrestrial arthropod, probably that of a spider. Many spiders form spherical cocoons around their egg masses (which they may carry or suspend from a web), or hemispherical ones (woven to a substrate), and the structure of the fossil silk strands conforms to that of spiders. No remains of eggs or spiderlings occur in the cocoon. Fossilized spider egg sacs are exceptionally rare, even in amber from prolific deposits.

The fossil record of spiders extends to the Devonian and has been reviewed several times (e.g., Selden et al., 2009; Seiden and Penney, 2010; Dunlop et al., 2018). Spiders are abundant and very diverse in the major amber deposits of the world, from the Early Cretaceous to the Miocene, allowing conclusions that many (most?) modern families are Cretaceous in origin, and that spiders were hardly affected by the end-Cretaceous extinctions, at least at higher-taxon (e.g., family) levels (Penney et al., 2003).

Two pieces of amber, AMNH WH-12 and AMNH WH-11, contain fragmentary remains of small roaches, probably nymphs. WH-12 contains a portion of one leg: apical portion of the femur and the entire tibia and tarsus. The tibia has 18 spinelike setae (including a pair of apical tibial spurs), in roughly four longitudinal rows. WH-11 contains portions of three legs and an antenna, all very dark and surrounded by a dark reddish “halo” of pyritization/oxidation. One leg is preserved as a portion of a femur; the tarsi and portions of the tibia are preserved for the other two legs. Approximately 30 filiform flagellomeres are preserved; the basal ones short (lengths about twice the width), gradually increasing in length distad to about five times the width. Leg segments of WH-11 are shorter than in WH-12, and tarsomere four has a long ventral lobe. Thus, there appears to be two taxa of roaches. Though these specimens cannot be identified to family or superfamily, they are clearly Blattodea based on the antennal structure and the tibial spines, which further have minute serrations on the ventral margin.

The fossil record and natural history of roaches are reviewed by Grimaldi and Engel (2005). The natural distribution of Blattodea worldwide is almost entirely tropical to warm temperate; pest species reach higher latitudes in association with human habitations. Of the 69 species of roaches in North America, 24 are introduced from other regions, and only three native species (Parcoblatta pensylvanica, P. uhleriana, and P. virginica) have distributions that extend into southernmost Ontario and Québec (Vickery and McKevan, 1985; Atkinson et al., 1991). The roaches are the most obvious example in Chickaloon amber of a taxon that has retreated from high northern latitudes.

AMNH LC-B6: A piece of amber containing a complete but minute (0.60 mm body length), wingless thrips, presumably a nymph (fig. 7C, D). The body is slightly compressed and distorted, the opaque body contents preventing observation of cuticular microsculpture, chaetotaxy, and sutures. The head is not well preserved, being partially collapsed, but the postocular region does not appear long (as in Phlaeothripidae); mouthparts are not visible. Antennae are preserved well enough to reveal segment proportions, cuticular microstructure, and sensilia (fig. 12B), their total lengths 440–460 µm. There are seven antennomeres, plus a minute terminal stylus, with relative lengths: 7 > 5 = 3 > 4 > 6 = 1 > 2. Most antennomeres have very fine transverse wrinkles and minute setigerous pimples; article 3 is the broadest and bears sensorial plaques, several of which also appear to occur on article 2; sensory cones appear to be absent, as do any thickened, blunt, setiform sensilia (fig. 12B). Femora are moderately thick (approximately twice the thickness of the tibiae); tarsi appear to be 1-segmented (best seen ventrally on the midlegs). Abdomen is somewhat fusiform in shape, with a small lateral lobe on most tergites (6 are visible) bearing a pair of recurved setae (fig. 12A). Presumably there is a pair of these lobes on each of the segments. Apex of the abdomen appears laterally compressed, the tip rounded and bearing a pair of long setae.

In lieu of wings and other structures it is difficult to definitively place the thrips to family, though the antennal structure provides good information. Seven antennomeres are found in the Uzelothripidae and in most Thripidae and Phlaeothripidae (which also have 1-segmented tarsi); thrips plesiomorphically have nine antennomeres. Uzelothripidae is highly doubtful, since the fossil does not have antennomeres 3 + 4 fused or an annulate apical segment (also, the family is monotypic in the Recent fauna, and has just one fossil species, in Early Eocene Oise amber from France [Nel et al., 2011]). Phlaeothripidae further have sensoria on segments three and four, but given that the postocular region of the head in LC-B6 does not appear long (perhaps preservational), and the terminal abdominal segment is not tubular, placement of the fossil in this family is uncertain. Phlaeothripidae and Thripidae comprise some 85% of the approximately 6000 living species of thrips, and they have diverse diets, which include phytophagy, pollenivory, and mycophagy. The oldest Thysanoptera are Late Triassic (Grimaldi et al., 2004); the oldest Thripidae and Phlaeothripidae occur in Early Cretaceous amber and are diverse in Cenozoic ambers (Nel et al., 2010). This is the northernmost fossil occurrence of Thysanoptera.

AMNH LC-A4: Amber piece contains most of a nymphal heteropteran (0.56 mm body length). Very little can be said about this specimen since it is fragmentary and portions of it are obscured (lying under a cracked and chipped corner of the amber); it is also very small, probably an early instar. It is clearly identifiable as a heteropteran, though, based on a proboscis that is curved anteroventrally, with a thick labium at the base and with fine stylets separated and exposed from the dorsal groove of the labium. Also, there are 2–3 short tarsomeres and the antenna is comprised of four thick flagellomeres that are held forward. Heteroptera are generally uncommon to rare in Cretaceous and Cenozoic amber, often comprising less than 1% of the individual arthropods. The fossil history of Heteroptera is reviewed by Grimaldi and Engel (2005).

Eleven pieces of amber contain the partial or complete remains of 21 wingless aphids (nymphs and/or apterae), as follows: AMNH LC-A2, 1 individual; LC-C4, partial aphid?; LC-D3, 1 individual; LC-II-A4, 2 aphids; LC-II-A6, 1 complete, 1 partial; LC-II-C2, 1.5 aphids, very small (early instar?); WH-4, 1 individual; WH-5, 4.5 aphids, same species and all approximately same size; WH-7, 2 partial aphids; WH-8, 3 very small (early instar?) individuals; WH-9, 1 individual. Many are incomplete, heavily pyritized, or too poorly preserved for detailed study, but four pieces contain specimens amenable to detailed study at 100x–400x magnification. Among these four, AMNH LC-A2 and LC-D3 clearly belong to the same species (species A); the specimens in WH-5 belong to a different species (sp. B), since they have longer legs, the abdomen is not as short and broad, and distal segments of the rostrum are distinctly different. AMNH LC-II-C2 contains one partial and one complete aphid, both very small (probably early instar nymphs), but which appear to have shorter, more compact flagellomeres. Body lengths range from 0.40 mm (WH-8) to 1.66 mm (WH-4).

Both species, A and B, clearly belong to the same family and genus, sharing the following features (fig. 13): Rostrum very long (slightly longer than body), 3-segmented, apex extending beyond apex of abdomen, apical two segments of rostrum distinctly swollen. Eyes small, inconspicuous; antenna 4-segmented, basal 2 antennomeres short, apical two articles approximately equal in length, apical articles apparently without rhinaria (or these are few, small, and obscure); head and notai sclerites possibly fused into shield (difficult to observe); tarsi 2-segmented, with small, oblique basitarsomere, pretarsal claws large and stout; abdominal tergites apparently without wax plates; siphunculi absent (presence/absence of siphuncular pores not observable); cauda apparently absent, or so small as to not be observable; body lacking enlarged or other specialized setae. The antennal segmentation, long rostrum, and structure of the abdominal apex indicate these species are in the Mesozoicaphididae according to the diagnosis by Heie and Pike (1992, 1996).

The Chickaloon aphids are clearly a very important group for understanding the paleoecology and biogeography of the Chickaloon amber. A long siphon and stout pretarsal claws are found in aphids that feed in the fissures of bark; this and the abundance of apterous forms in the amber indicate that the aphids were feeding on the tree that produced the amber. Modern Aphidoidea that feed on conifers include many Adelgidae, which seem to be a specialized offshoot of certain Cretaceous aphids. The Mesozoicaphididae, to which the Chickaloon aphids appear to belong, were placed in the Phylloxeroidea by Heie and Pike (1992), a family that until now was known only from Late Cretaceous (Campanian-aged) amber of western Canada (Heie and Pike, 1992).

Canadian Cretaceous amber contains abundant and diverse aphids, some 16 species in 10 genera and several families (Essig, 1938; Richards, 1966; Heie and Pike, 1992, 1996; Kania and Wegierek, 2005), although the taxonomy and classification needs to be reexamined. In amber from Medicine Hat, Alberta (Foremost Formation, or Foremost Member of the Judith River Formation [Campanian]), aphids comprise some 35%–40% of all individual arthropod inclusions (Heie and Pike, 1992). The tree that is the best candidate for the production of the Canadian Cretaceous amber is also in the Cupressaceae, specifically Parataxodium (an extinct genus closely related to Taxodium and Glyptostrobus) (McKellar and Wolfe, 2010). Aphids are also abundant in Late Cretaceous Siberian amber from the Taimyr Peninsula (Zherikhin and Sukatsheva, 1973); in Late Eocene Baltic amber aphids comprise some 2% of arthropod inclusions (Larsson, 1978). Early Eocene amber from Hat Creek, British Columbia, is also preserved in strata that contain abundant Metasequoia remains, as well as Glyptostrobus (Read, 1990; Legun, 1996); Hemiptera are reported in that amber (Poinar et al., 1999), but there is no mention of aphids. Aphids are rare in amber from the Miocene of the Dominican Republic and Mexico, Eocene of Ukraine, and the Cretaceous of Lebanon, Myanmar, New Jersey, and Spain; they are absent in amber from the Eocene and Cretaceous of France (see contributions in Penney, 2010). Thus, like the Recent, aphids have been primarily higher latitude insects since the Cretaceous, though they did not become abundant until the Cenozoic.

AMNH LC-II-B4: A partial larva that is missing the head and legs, but has seven abdominal segments largely to entirely preserved (portions of the anterior segments are lost at the amber surface on the right side) (fig. 8A). The dorsum of the abdomen is covered with a dense vestiture of long setae having short, thick plumosity; presence/absence of bare patches on tergites is not observable. The apical abdominal segments have tufts of peculiar spear-shaped setae, which are very well preserved. These specialized setae have a bullet-shaped head that is hollow, with an asymmetrical, sharp basal rim; the setal shaft has evenly spaced nodes, each node with a crenulated collar of small spines or tubercles (fig. 14F). Such setae, called hastisetae, allowed identification of the partial larva to the Dermestidae, and in fact hastisetae of this structure are confined to the subfamily Megatominae (Kiselyova and McHugh, 2006), most similar to the genus Cryptorhopalum. The hastisetae in extant dermestids are defensive, being dehiscent and snagging together when the larva is attacked, entangling the attacker (Nutting and Spangler, 1969). There are 1300 living species of Dermestidae in 53 genera, well-known for their larval diet of dried animal remains (including carrion, and shed feathers, hairs, and skin in nests). The genus Anthrenus (also a megatomine) is the notorious museum pest that decimates unprotected collections of skins and pinned insects. The oldest putative dermestid is in Jurassic shale (Deng et al., 2017), with definitive larvae and adults in Early Cretaceous amber from Lebanon (Kirejtshuk et al., 2009), and the oldest Attageninae from the mid-Cretaceous of Myanmar (Cai et al., 2017) and Late Cretaceous of New Jersey (Peris and Háva, 2016). Hastisetae of megatomine dermestids are preserved in Upper Albian-aged amber from Spain, snagged in the legs and body of ticks (Peñalver et al., 2017). The ticks most likely acquired the hastisetae in the arboreal nest of a vertebrate host (Peñalver et al., 2017). Diverse modern genera of dermestids occur in Eocene Baltic amber (e.g., Háva et al., 2008) and Miocene Dominican amber. The Chickaloon amber specimen is the most northerly fossil record of the Dermestidae, the prior ones being in Baltic amber.

AMNH WH-12: The amber piece contains the apical third or so of two partially overlapping wings and the distal portions of three legs. Preserved leg portions include portions of the tibiae and entire tarsi. There are five rather long tarsomeres, the basitarsomere significantly the longest. The pretarsal claws are well developed and the empodium is pulvilliform. These remains are identifiable as Trichoptera based on the dense vestiture of long, fine setae on the wing veins and membrane; and legs with short, slender, spinelike setae, especially circlets of these at the apices of leg podites. No diagnostic features are preserved that allow identification to family or even superfamily/subordinal level. Larval Trichoptera inhabit freshwater (rarely are semiterrestrial), and are well-known for their construction of cases, sometimes elaborate ones. Definitive Trichoptera first appeared in the Jurassic; the fossil record is reviewed by Grimaldi and Engel (2005). Baltic amber is the most abundant and diverse source of fossil Trichoptera, which otherwise are uncommon in amber. AMNH WH-12 is the largest arthropod preserved in the Chickaloon amber (albeit partial), with an estimated body length of 6 mm.

AMNH WH-3: A complete male nonbiting midge (Chironomidae) (body length 1.60 mm), preserved adjacent to a small juvenile spider (fig. 7E). Eyes are bare; pedicel large, subspherical; antenna with long plumosity, apparently having 11 flagellar articles, apical article longest; maxillary palp with four palpomeres, lengths 4 > 2 = 3 > 1 (fig. 14C). Legs: mesotibia having two bladelike apical spurs (one with fine pectination), apical comb of 11-12 thick, sclerotized, slightly clavate setae (fig. 14D); pretarsal claws simple (untoothed), pulvilli either minute or lost. Wings are very faint, obscuring the venation; no macrotrichia occur on the wing membrane. Male genitalia well preserved: tergite 9 (epandrium) large, shieldlike; gonocoxite large; gonostylus articulating with (not fused to) gonocoxite, bare, flattened and hatchetlike, without discernable apical peg/tooth; pair of inner lobes present, bare; anal point absent (fig. 14A, B).

Chironomidae have a rich fossil record, partly because the larvae are aquatic and semiaquatic and both adults and larvae are readily fossilized in lacustrine sediments. The oldest Chironomidae are Triassic, and they are frequently among the most abundant and diverse winged insects in many deposits of amber, such as Eocene Baltic amber and Late Cretaceous ambers from western Canada, New Jersey, and Siberia. The fossil record has been reviewed by Evenhuis (1994). Critical study relies on various microscopic features, and most of the described fossils, done decades to a century ago, require re-description based on modern standards. The male genitalia of the Chickaloon fossil appear most similar to those in the large, widespread subfamily Tanypodinae.

AMNH WH-1: A single worker ant specimen, approximately 1.7 mm total body length (excluding antennae), attributable to the subfamily Formicinae. The acidopore, a primary diagnostic feature of formicine ants, appears faintly visible as a circular opening at the terminus of the abdomen. The petiole—a waistlike segment separating the trunk and gaster—is conspicuously scale shaped, with its dorsal margin reaching the same approximate height as the propodeum, a syndrome found in multiple extant and fossil formicine genera. Specimen WH-1 is heavily desiccated and partially disarticulated, making precise placement difficult. Nevertheless, the specimen clearly does not fit into any currently described genus of formicine, in particular due to its widely spaced mandibular dentition and shortened antennal scape (figs. 9B, C). The isolated antenna of another ant specimen, in piece GC-A4 (fig. 14E), has different segmental proportions than the formicine above, indicating the existence of another ant species in this amber. Very little can be determined taxonomically on the basis of an antenna.

The subfamily Formicinae is presently distributed worldwide, and fossils are similarly cosmopolitan. In total, 196 fossil formicine species are described, comprising 43 genera from 44 localities across North America, Europe, Asia, and New Zealand (Barden, 2017). Potentially a result of high sampling bias (nearly 13,000 ant inclusions were utilized in a recent analysis of ant species richness [Penney and Preziosi, 2014]), nearly 40 formicine species are described from Baltic amber, the greatest of any deposit. The Chickaloon amber species has not yet been formally described, however, it may represent a stem relative of the primarily Palearctic and Nearctic tribe Formicini or the cosmopolitan tribe Lasiini, based on current understanding of relationships (e.g., Lapolla et al., 2010; Ward et al., 2016)—both represented in the fossil record, including in Baltic amber. This preliminary diagnosis is based on the large circular propodeal spiracle, gradually sloping mesonotum, 5:4 palpomere formula, and mandibular shape. Interestingly, this new specimen is contemporaneous with formicine ants described from Fushun amber (Hong, 2002), making it, along with its counterparts in Asia, the oldest formicines known following Kyromyrma neffi in Turonian-aged New Jersey amber (Grimaldi and Agosti, 2000). This is a valuable window into ant evolution as the Fushun amber holotypes have since been lost. Slightly younger ants (Dolichoderinae, Myrmecinae, Formicinae, and Myrmeciinae) are reported in mid to Late Eocene shales and Hat Creek amber from British Columbia (Archibald et al., 2018). It should be noted that the identification of Technomyrmex (Dolichoderinae) in Poinar et al. (1999) was changed to Formicinae incertae sedis in Archibald et al. (2018).