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BLATTODEA (COCKROACHES) Figure 7A 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 Qu��bec (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., Published as part of Grimaldi, David A., Sunderlin, David, Aaroe, Georgene A., Dempsky, Michelle R., Parker, Nancy E., Tillery, George Q., White, Jaclyn G., Barden, Phillip, Nascimbene, Paul C. & Williams, Christopher J., 2018, Biological Inclusions in Amber from the Paleogene Chickaloon Formation of Alaska, pp. 1-37 in American Museum Novitates 2018 (3908) on page 20, DOI: 10.1206/3908.1, http://zenodo.org/record/4598569, {"references":["Grimaldi, D. A., and M. S. Engel. 2005. Evolution of the insects. New York: Cambridge University Press.","Atkinson, T. H., P. G. Koehler, and R. S. Patterson. 1991. Catalog and atlas of the cockroaches (Dictyoptera) of North America north of Mexico. Miscellaneous Publications of the Entomological Society of America 78: 1 - 86."]}

ACARI (MITES) Figures 5H, 11A AMNH WH-6: A small piece containing most of the remains of an oribatid mite, similar in overall structure to the family Damaeidae (fig. 11A), 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, sensilla, 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 sensilla, 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 BehanPelletier, 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 (400−1000×) 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.

DERMESTIDAE (CARPET BEETLES) Figures 8 A���C; 14F 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 tu��s 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 sha�� 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 H��va, 2016). Hastisetae of megatomine dermestids are preserved in Upper Albian���aged amber from Spain, snagged in the legs and body of ticks (Pe��alver et al., 2017). The ticks most likely acquired the hastisetae in the arboreal nest of a vertebrate host (Pe��alver et al., 2017). Diverse modern genera of dermestids occur in Eocene Baltic amber (e.g., H��va 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., Published as part of Grimaldi, David A., Sunderlin, David, Aaroe, Georgene A., Dempsky, Michelle R., Parker, Nancy E., Tillery, George Q., White, Jaclyn G., Barden, Phillip, Nascimbene, Paul C. & Williams, Christopher J., 2018, Biological Inclusions in Amber from the Paleogene Chickaloon Formation of Alaska, pp. 1-37 in American Museum Novitates 2018 (3908) on page 25, DOI: 10.1206/3908.1, http://zenodo.org/record/4598569, {"references":["Kiselyova, T., and J. V. McHugh. 2006. A phylogenetic study of Dermestidae (Coleoptera) based on larval morphology. Systematic Entomology 31: 469 - 507.","Nutting, W. L., and H. G. Spangler. 1969. The hastate setae of certain dermestid larvae: an entangling defense mechanism. Annals of the Entomological Society of America 62: 763 - 769.","Deng, C., A. Slipinski, D. Ren, and H. Pang. 2017. The oldest dermestid beetle from the Middle Jurassic of China (Coleoptera: Dermestidae). Annales Zoologici 67: 109 - 112.","Kirejtshuk, A. G., D. Azar, P. Tafforeau, R. Boistel, and V. Fernandez. 2009. New beetles of Polyphaga (Coleoptera, Polyphaga) from Lower Cretaceous Lebanese amber. Denisia 26: 119 - 130.","Cai, C., J. Hava, and D. Huang. 2017. The earliest Attagenus species (Coleoptera: Dermestidae: Attageninae) from Upper Cretaceous Burmese amber. Cretaceous Research 72: 95 - 99.","Peris, D., and J. Hava. 2016. New species from Late Cretaceous New Jersey amber and stasis in subfamily Attageninae (Insecta: Coleoptera: Dermestidae). Journal of Paleontology 90: 491 - 498.","Penalver, E., et al. 2017. Ticks parasitised feathered dinosaurs as revealed by Cretaceous amber assemblages. Nature Communications 8: 1924. [doi: 10.1038 / s 41467 - 017 - 01550]","Hava, J., J. Prokop, and A. Herrmann. 2008. New fossil dermestid beetles (Coleoptera: Dermestidae) from the Baltic amber-III. Acta Societatis Zoologicae Bohemicae 17 (2007): 151 - 157."]}

FORMICIDAE (ANTS) Figures 9 A���C 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)., Published as part of Grimaldi, David A., Sunderlin, David, Aaroe, Georgene A., Dempsky, Michelle R., Parker, Nancy E., Tillery, George Q., White, Jaclyn G., Barden, Phillip, Nascimbene, Paul C. & Williams, Christopher J., 2018, Biological Inclusions in Amber from the Paleogene Chickaloon Formation of Alaska, pp. 1-37 in American Museum Novitates 2018 (3908) on page 28, DOI: 10.1206/3908.1, http://zenodo.org/record/4598569, {"references":["Barden, P. 2017. Fossil ants (Hymenoptera: Formicidae): ancient diversity and the rise of modern lineages. Myrmecological News 24: 1 - 30.","Penney, D., and R. F. Preziosi. 2014. Estimating fossil ant species richness in Eocene Baltic amber. Acta Palaeontologica Polonica 59: 927 - 929.","Lapolla, J. S., S. G. Brady, and S. O. Shattuck. 2010. Phylogeny and taxonomy of the Prenolepis genus-group of ants (Hymenoptera: Formicidae). Systematic Entomology 35: 118 - 131.","Ward, P. S., B. B. Blaimer, and B. B. and B. L. Fisher. 2016. A revised phylogenetic classification of the ant subfamily Formicinae (Hymenoptera: Formicidae), with resurrection of the genera Colobopsis and Dinomyrmex. Zootaxa 4072: 343 - 357.","Hong, Y. 2002. Amber insects of China. Beijing: Beijing Scientific and Technological Publishing House.","Grimaldi, D., and D. Agosti, D. 2000. A formicine in New Jersey Cretaceous amber (Hymenoptera: Formicidae) and early evolution of the ants. Proceedings of the National Academy of Sciences of the United States of America 97: 13678 - 13683.","Poinar, G., B. Archibald, and A. Brown. 1999. New amber deposit provides evidence of early Paleogene extinctions, paleoclimates, and past distributions. Canadian Entomologist 131: 171 - 177."]}

FORMICIDAE (ANTS) Figures 9 A−C 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).

DERMESTIDAE (CARPET BEETLES) Figures 8 A−C; 14F 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 tuπs 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 shaπ 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.

CHIRONOMIDAE (MIDGES) Figures 7E, 14 A���D 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., Published as part of Grimaldi, David A., Sunderlin, David, Aaroe, Georgene A., Dempsky, Michelle R., Parker, Nancy E., Tillery, George Q., White, Jaclyn G., Barden, Phillip, Nascimbene, Paul C. & Williams, Christopher J., 2018, Biological Inclusions in Amber from the Paleogene Chickaloon Formation of Alaska, pp. 1-37 in American Museum Novitates 2018 (3908) on page 27, DOI: 10.1206/3908.1, http://zenodo.org/record/4598569, {"references":["Evenhuis, N. L. 1994. Catalogue of the fossil flies of the world (Insecta: Diptera). Leiden: Backhuys Publishers."]}

CHIRONOMIDAE (MIDGES) Figures 7E, 14 A−D 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.

ARANEAE (SPIDERS) Figures 5 A−F, 7E 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; Selden 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).

THYSANOPTERA (THRIPS) Figures 7C, D; 12A, B 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 sensilla (fig. 12B), their total lengths 440���460 ��m. 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 sensilla (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., Published as part of Grimaldi, David A., Sunderlin, David, Aaroe, Georgene A., Dempsky, Michelle R., Parker, Nancy E., Tillery, George Q., White, Jaclyn G., Barden, Phillip, Nascimbene, Paul C. & Williams, Christopher J., 2018, Biological Inclusions in Amber from the Paleogene Chickaloon Formation of Alaska, pp. 1-37 in American Museum Novitates 2018 (3908) on pages 20-22, DOI: 10.1206/3908.1, http://zenodo.org/record/4598569, {"references":["Nel, P., A. R. Schmidt, C. Bassler, and A. Nel. 2011. Fossil thrips of the family Uzelothripidae suggest 53 million years of morphological and ecological stability. Acta Palaeontologica Polonica 58 (3): 609 - 614.","Grimaldi, D., A. Shmakov, and N. Fraser. 2004. Mesozoic thrips and early evolution of the order Thysanoptera (Insecta). Journal of Paleontology 78: 941 - 952.","Nel, P., E. Penalver, D. Azar, G. Hodebert, and A. Nel. 2010. Modern thrips families Thripidae and Phlaeothripidae in Early Cretaceous amber (Insecta: Thysanoptera). Annales de la Societe Entomologique de France 46: 154 - 163."]}

THYSANOPTERA (THRIPS) Figures 7C, D; 12A, B 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 sensilla (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 sensilla (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.

BLATTODEA (COCKROACHES) Figure 7A 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.

ACARI (MITES) Figures 5H, 11A AMNH WH-6: A small piece containing most of the remains of an oribatid mite, similar in overall structure to the family Damaeidae (fig. 11A), 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 ��m, with a slight constriction between the prodorsum and notogaster; legs are long and slender, length of the longest is 550 ��m. The mite is dark and opaque, generally obscuring many of the setae, sensilla, 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 ��m 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 sensilla, 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 BehanPelletier, 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���1000��) 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., Published as part of Grimaldi, David A., Sunderlin, David, Aaroe, Georgene A., Dempsky, Michelle R., Parker, Nancy E., Tillery, George Q., White, Jaclyn G., Barden, Phillip, Nascimbene, Paul C. & Williams, Christopher J., 2018, Biological Inclusions in Amber from the Paleogene Chickaloon Formation of Alaska, pp. 1-37 in American Museum Novitates 2018 (3908) on pages 16-17, DOI: 10.1206/3908.1, http://zenodo.org/record/4598569, {"references":["Weitschat, W., and W. Wichard. 2010. Baltic amber. Chapter 6. In D. Penney (editor), Biodiversity of fossils in amber from the major world deposits: 80 - 115. Manchester: Siri Scientific Press.","Perkovsky, E. E., V. Yu. Zosimovich, A. P. Vlaskin. 2010. Rovno amber. Chapter 7. In D. Penney (editor), Biodiversity of fossils in amber from the major world deposits: 116 - 136. Manchester: Siri Scientific Press.","Norton, R. A., P. M. Bonamo, J. D. Grierson, and W. A. Shear. 1988. Oribatid mite fossils from a terrestrial Devonian deposit near Gilboa, New York. Journal of Paleontology 62: 259 - 269.","Labandeira, C. C., T. L. Phillips, and R. A. Norton. 1997. Oribatid mites and the decomposition of plant tissues in Paleozoic coal-swamp forests. Palaios 12: 319 - 353.","Dunlop, J. A., D. Penney, and D. Jekel. 2018. A summary list of fossil spiders and their relatives. The world spider catalog. Natural History Museum Bern. Online resource (http: // wsc. nmbe. ch), version 19.0, accessed on 10 March 2018. [doi: 10.24436 / 2]","Sidorchuk, E. A. 2013. A new technique for the preparation of small-sized amber samples with application to mites. In Insect Evolution in an amberiferous and stone alphabet. Proceedings of the 6 th International Congress on Fossil Insects, Arthropods and Amber: 189 - 201. Leiden: E. J. Brill.","Norton, R. A. 2000. First record of Collohmannia (C. schusteri n. sp.) and Hermannia (H. sellnicki n. sp.) from Baltic amber, with notes on Sellnick's genera of fossil oribatid mites (Acari: Oribatida). Acarologia 46 (1 - 2), 111 - 125.","Sidorchuk, E. A., and R. A. Norton. 2010. Redescription of the fossil oribatid mite Scutoribates perornatus, with implications for systematics of Unduloribatidae (Acari: Oribatida). Zootaxa 2666: 45 - 67.","Sidorchuk, E. A., and R. A. Norton. 2011. The fossil mite family Archaeorchestidae (Acari, Oribatida) II: redescription of Plategeocranus sulcatus and family-group relationships. Zootaxa 3051: 14 - 40."]}