New bird remains from the early Eocene Nanjemoy Formation of Virginia (USA), including the first records of the Messelasturidae, Psittacopedidae, and Zygodactylidae from the Fisher/Sullivan site

Figures & data

Figure 1. (a)‒(l), (n) Bones from the early Eocene of the Nanjemoy Formation, which are assigned to the Charadriiformes, Procellariiformes, and Messelornithidae, in comparison to (m) a messelornithid from the early Eocene Belgium. (a), (b) Charadriiformes, gen et sp. indet., proximal end of left humerus (USNM PAL 771602) in caudal (a) and cranial (b) view. (c), (d) Charadriiformes, gen et sp. indet., proximal end of left humerus (USNM PAL 771603) in caudal (c) and cranial (d) view. (e) Distal end of right humerus of a charadriiform bird (SMF Av 619) described by Mayr (2016); cranial view. (f), (g) Distal end of right humerus (USNM PAL 496374), which was assigned to the Scolopaci by Olson (1999) in cranioventral (f) and cranial (g) view; this bone is here considered to be from a procellariiform bird. (h) Distal end of a left tarsometatarsus (SMF Av 617), which was tentatively assigned to the Procellariiformes by Mayr (2016); plantar view. (i) Distal end of right tarsometatarsus (USNM PAL 496375), which was assigned to the Scolopaci by Olson (1999); plantar view. (j) Distal end of right tarsometatarsus (SMF Av 622), which was tentatively assigned to the Messelornithidae by Mayr (2016); plantar view. (k) Distal end of a right tarsometatarsus (USNM PAL 496419), which was tentatively assigned to Coturnipes by Olson (1999). (l) Distal end of the left tarsometatarsus of Coturnipes cooperi from the early Eocene of the London Clay (holotype; NHMUK A 3706); plantar view. (m) Distal portion of the left tarsometatarsus of an unnamed species of the Messelornithidae from the early Eocene of Egem in Belgium (IRSNB Av 170); plantar view. (n) Distal portion of an undetermined charadriiform-like right tarsometatarsus in plantar view (USNM PAL 771607). Abbreviations: icb, impressio coracobrachialis; psd, processus supracondylaris dorsalis; rdg, ridge formed by caudal surface of shaft; snc, sulcus nervi coracobrachialis; tbd, tuberculum dorsale. The scale bars equal 5 mm. [Colour online].

Figure 2. (a)‒(f) Right tarsometatarsus of Parvicuculus sp. from the early Eocene of the Nanjemoy Formation (USNM PAL 496384), which is assigned to the Parvicuculidae, in dorsal (a), plantar (b), medial (c), lateral (d), proximal (e), and distal (f) view. (g) Right tarsometatarsus of Parvicuculus minor in plantar view (holotype; NHMUK A 4919). (h) Left tarsometatarsus of a bird from the early Eocene Green River Formation, which was referred to Fluvioviridavis platyrhamphus (from Nesbitt et al. 2011: fig. 6); lateral view. Abbreviations: cmp, crista medianoplantaris; flg, plantarly directed flange on trochlea metatarsi IV; fvd, foramen vasculare distale. The scale bars equal 5 mm. [Colour online].

Figure 3. (a)‒(d), (g)‒(j) Bones from the early Eocene of the Nanjemoy Formation, which are assigned to the Halcyornithidae in comparison to (e), (f) halcyornithid specimens from the London Clay. (a), (b) Proximal end of right humerus (USNM PAL 771600) in cranial (a) and caudal (b) view. (c), (d) Distal end of right humerus (USNM PAL 771599) in cranial (c) and caudal (d) view. (e) Proximal end of left humerus of a halcyornithid from the early Eocene London Clay of the Isle of Sheppey (NHMUK A 3553). (f) Distal end of right humerus of a halcyornithid from the Isle of Sheppey (NHMUK A 6155). (g)‒(i) Distal end of left tibiotarsus from the Nanjemoy Formation (USNM PAL 771605) in cranial (g, i) and caudal (h) view; in (i) the specimen was mirrored to show the matching articulation with (j) a right tarsometatarsus of a halcyornithid species reported by Mayr (2016), which is depicted in dorsal view (SMF Av 628). Abbreviations: psd, pons supratendineus; stv, sulcus transversus; tbd, tuberculum dorsale; tsd, tuberculum supracondylare dorsale. The scale bars equal 5 mm. [Colour online].

Figure 4. Bones from the early Eocene of the Nanjemoy Formation, which are assigned to the Messelasturidae in comparison to messelasturids from other localities. (a)‒(e) Undetermined messelasturid from the Nanjemoy Formation, gen. et sp. indet. A (cf. Messelastur), distal end of left tarsometatarsus (USNM PAL 771595) in dorsal (a), plantar (b), lateral (c), medial (d), and distal (e) view. (f)‒(j) Undetermined messelasturid from the Nanjemoy Formation, gen. et sp. indet. B (cf. Tynskya), distal end of right tarsometatarsus (USNM PAL 771596) in distal (f), dorsal (g), plantar (h), medial (i); and lateral (j) view. (k) Left foot (plantar view) of Messelastur gratulator from the latest early or earliest middle Eocene of Messel, Germany (SMF-ME 11348). (l)‒(o) Partial right carpometacarpus from the Nanjemoy Formation (USNM PAL 771598) in ventral (l), ventrocaudal (m), dorsal (n), and ventrodorsal (o) view. (p) Proximal end of left carpometacarpus of Tynskya waltonensis (SMF Av 652) in ventral view. (q) Right carpometacarpus of Tynskya eocaena from the early Eocene Green River Formation, Wyoming, USA (holotype, SNSB-BSPG 1997) in ventral view. In (b) and (h) the trochleae are numbered. Abbreviations: acc, trochlea accessoria; fvd, foramen vasculare distale; pex, processus extensorius. The scale bars equal 5 mm. [Colour online].

Figure 5. Bones from the early Eocene of the Nanjemoy Formation, which are assigned to the Psittacopedidae, in comparison to Pumiliornis tessellatus. (a)‒(e) cf. Pumiliornis, distal end of left tibiotarsus (USNM PAL 771594) in cranial (a), medial (b), caudal (c), lateral (d), and distal (e) view. (f) Distal end of right tibiotarsus of Pumiliornis tessellatus from the latest early or earliest middle Eocene of Messel, Germany, in cranial view (SMF-ME 2475B). (g)‒(l) cf. Pumiliornis, left tarsometatarsus (USNM PAL 771592) in plantar (g), dorsal (h), lateral (i), medial (j), proximal (k), and distal (l) view. (m) Right tarsometatarsus of P. tessellatus from Messel in plantar view (SMF-ME 11414A; note that the scale bars in Figure 1d‒g of Mayr and Wilde 2014 are incorrect and represent 5 mm [Figure 1d] and 2 mm [Figure 1e‒g], respectively). Abbreviations: acc, trochlea accessoria; cdl, condylus lateralis; cdm, condylus medialis; fdl, hypotarsal canal for tendon of musculus flexor digitorum longus; fhl, hypotarsal sulcus for tendon of musculus flexor hallucis longus; fvd, foramen vasculare distale; tre, lateral tuberositas retinaculi extensori. The scale bars equal 5 mm. [Colour online].

Figure 6. Bones from the early Eocene of the Nanjemoy Formation, which are assigned to Zygodactylidae. (a)‒(c) Zygodactylidae, gen. et sp. indet., right tarsometatarsus (USNM PAL 771590) in dorsal (a), plantar (b), and proximal (c) view. (d)‒(f) Zygodactylidae, gen. et sp. indet., right coracoid (USNM PAL 771591) in dorsal (d), ventral (e), and medial (f) view. Abbreviations: acc, trochlea accessoria; fas, facies articularis scapularis; fdl, hypotarsal canal for tendon of musculus flexor digitorum longus; fhl, hypotarsal sulcus for tendon of musculus flexor hallucis longus; fvd, foramen vasculare distale. The scale bars equal 5 mm. [Colour online].

Figure 7. (a)‒(e) Partial right tarsometatarsus of Aves indet. A. (?Morsoravis), from the early Eocene of the Nanjemoy Formation (USNM PAL 771593) in plantar (a), medioplantar (b), mediodorsal (c), medial (d), and distal (e) view. (f), (g) Distal end of a right tarsometatarsus (SMF Av 634), which was likened to Morsoravis by Mayr (2016) in dorsal (f) and plantar (g) view. (h) Left tarsometatarsus (dorsal view) of Morsoravis sedilis from the early Eocene Fur Formation in Denmark (holotype, MGUH 28930); dorsal view, surrounding matrix was digitally removed. Abbreviation: mtI, fossa metatarsi I. The tarsometatarsal trochleae are numbered. The scale bars equal 5 mm. [Colour online].

Figure 8. Undetermined avian bones from the early Eocene of the Nanjemoy Formation. (a), (b) Aves indet. B, right humerus (USNM PAL 771608) in caudal (a) and cranial (b) view. (c)‒(f) Aves indet. C, extremitas omalis of right coracoid (USNM PAL 771601) in dorsal (c), ventral (d), lateral (e), and medial (f) view. (g), (h) Aves indet. D, distal end of left humerus (USNM PAL 771604) in cranial (g) and caudal (h) view. (i)‒(k) Aves indet. E, extremitas omalis of left coracoid (USNM PAL 771606) in dorsal (i), ventral (j), and medial (k) view. Abbreviations: fns, foramen nervi supracoracoidei; ldg, ledge formed by processus procoracoideus; ppc, processus procoracoideus; psd, processus supracondylaris dorsalis; tbd, tuberculum dorsale. The scale bars equal 5 mm. [Colour online].

Table 1. Revised overview of the avian taxa from the Nanjemoy Formation, with known elements indicated (cmc: carpometacarpus, hum: humerus, tbt: tibiotarsus, tmt: tarsometatarsus)

Taxon	Remarks	Known elements
Pelagornithidae	Olson (1999)	partial cmc and pedal phalanx
?Procellariiformes	Mayr (2016)	distal tmt, distal humerus
?Fregatidae (cf. Limnofregata)	Mayr (2016)	proximal cmc
Charadriiformes indet. sp. A	Mayr (2016)	distal hum
Charadriiformes indet. sp. B	Olson (1999), this study	distal hum, distal tbt, distal tmt
?Charadriiformes indet.	this study, may be conspecific with the humerus of sp. A	distal tmt (USNM PAL 771607)
?Messelornithidae, cf. Coturnipes	Olson (1999), Mayr (2016), this study	partial coracoid, distal hum, distal tmt
?Caprimulgidae	Olson (1999); identification needs to be corroborated	distal tmt
Parvicuculidae	assigned to Aegialornithidae by Olson (1999)	tmt, ?partial coracoid, “distal hum
cf. Steatornithidae	Olson (1999)	Hum, fragments of tmt
?Apodiformes, cf. Eocypselidae	Mayr (2016)	distal tmt, cmc
Strigiformes, Eostrix gulottai sp. nov.	Mayr (2016)	distal tmt
Halcyornithidae	Mayr (2016), this study	tmt
Messelasturidae, gen. et sp. A	this study	tmt
Messelasturidae, gen. et sp. A	this study	tmt
Psittacopedidae, cf. Pumiliornis	this study	distal tbt, tmt
Zygodactylidae	this study	tmt, coracoid
cf. Microena	Mayr (2016)	distal tmt, possibly a distal tibiotarsus assigned to the Trogoniformes by Mayr (2016)
cf. Morsoravis	Mayr (2016), this study	distal tmt
Gen. et sp. indet.	Mayr (2016), possibly the same species as “crane-sized” bird reported by Olson (1999)	pedal phalanx
Gen et sp. indet.	this study	partial coracoid (USNM PAL 771601)
Gen. et sp. indet. (cf. Threskiornithidae)	Mayr (2016), may be conspecific with the “graculavid” species #1 of Olson (1999), carpometacarpus identical with that referred to the Phoenicopteriformes by Olson (1999)	proximal hum, proximal radius, distal ulna, proximal cmc, wing phalanx
?Phoenicopteriformes	Olson (1999); may be conspecific with putative threskiornithid reported by Mayr (2016)	cmc, radius
‘Graculavidae, species 1’	Olson (1999); may be conspecific with putative threskiornithid reported by Mayr (2016)	partial scapula and coracoid, fragments of hum, proximal ulna, distal tbt
‘Graculavidae, species 2’	Olson (1999)	distal ulna, distal cmc

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