Review of Eocene birds from the Geiseltal (1 Viewer)

[albertonykus]

Mayr, G. (2020)
An updated review of the middle Eocene avifauna from the Geiseltal (Germany), with comments on the unusual taphonomy of some bird remains
Geobios (advance online publication)
doi: 10.1016/j.geobios.2020.06.011
https://www.sciencedirect.com/science/article/pii/S0016699520300693

The brown coal mines of the Geiseltal were among the most important middle Eocene fossil localities and constitute the reference sites for the Geiseltalian stage of the European Land Mammal Mega Zones. Here, an updated review of the Geiseltal avifauna is given. Thirteen species are represented by diagnostic bones and can be referred to avian higher-level taxa, but various indeterminable albeit distinct fossils indicate a higher diversity of the Geiseltal avifauna. The majority of the Geiseltal fossils belong to taxa which are well known from early to mid-Ypresian fossil sites of Europe and North America. Some of the species from the Geiseltal are larger than their early Eocene relatives, but it remains elusive whether this indicates an evolutionary size increase in some avian lineages or reflects different palaeohabitats of the involved fossil sites. The Geiseltal avifauna exhibits some taphonomic peculiarities that have not yet been addressed. Most bird fossils consist of isolated bones or partial skeletons and here it is hypothesized that at least some of the fragmentary specimens represent feeding remains of crocodilians. For the first time, medullary bone, which is indicative of breeding females, is reported for birds from the Geiseltal. The comparative abundance of the coliiform species Eoglaucidium pallas is remarkable, and either this species was extremely abundant in the Geiseltal ecosystem or it had ecological preferences which favored its preservation.

 

[Fred Ruhe]

Systematic palaeontology -1

Systematic palaeontology
Aves Linnaeus, 1758
Palaeognathae Pycraft, 1900
Palaeotididae Houde and Haubold, 1987
Palaeotis weigelti Lambrecht, 1928
Remarks: Houde and Haubold (1987) described four specimens of P. weigelti from MP 13 strata of the Cecilie and Leonhardt mines. At least one of these fossils stems from a Leichenfeld type of deposit. Mayr (2019) reported four further and previously unrecognized specimens of the species, one of which (GMH IX-566-1953) is from the Unterkohle (MP 11). The taxonomic identity of a distal tarsometatarsus (GMH 3605), which was referred to P. weigelti by Mayr (2002a), was considered to be uncertain by Mayr (2019).

Neognathae Pycraft, 1900
Gastornithidae Fürbringer, 1888
Gastornis geiselensis (Fischer, 1978)
Remarks: The fossil material of Gastornis geiselensis in the collection of GMH was surveyed by Hellmund (2013), who identified remains of at least nine individuals. These specimens stem from five vertebrate localities, which cover the Mammalian Paleogene Zones MP 11, 12, and 13 and mainly represent sinkholes or creeks. No Gastornis remains were found in the Leichenfeld type of deposits.

Cariamiformes Verheyen, 1957
Idiornithidae Brodkorb, 1965
?Dynamopterus anthracinus (Mayr, 2002a) nov. comb. Fig. 1(A‒D, F‒H)
Remarks: A large-sized tarsometatarsus (GMH LXIII-1-1983; Fig. 1(A‒D)) was referred to the Cariamiformes and described as a new species, ?Idiornis anthracinus, by Mayr (2002a). This fossil is a surface find from the obere Mittelkohle (MP 13) of the Mücheln mine. Here, two further specimens are tentatively referred to ?D. anthracinus nov. comb. One of these is from a juvenile bird with an “unfinished” bone surface and consists of a tarsometatarsus and other leg bone fragments on a slab (GMH 4357; Fig. 1(H)). The other specimen is a partial hindlimb preserved on a slab, which includes a tibiotarsus and pedal phalanges (GMH 5885; Fig. 1(F, G)). Both fossils appear to be from the old collections (before 1945) and are therefore likely to also be from MP 13. The taxon Idiornis Oberholser, 1899 was synonymized with Dynamopterus Milne-Edwards, 1892 by Mourer-Chauviré (2013), so that the Geiseltal species is now assigned to ?Dynamopterus anthracinus nov. comb. Apart from being significantly larger, the holotype closely resembles a tarsometatarsus of a cariamiform bird from Messel (Fig. 1(E)), which was tentatively referred to Dynamopterus (“Idiornis”) cf. itardiensis by Mayr (2000). It was, however, noted that the tarsometatarsi of early and middle Eocene Cariamiformes are much stouter than the elongated tarsometatarsi of the Dynamopterus species from the middle Eocene to late Oligocene Quercy fissure fillings (Mayr, 2000, 2009a), and the differences in proportions may justify an assignment of the early and middle Eocene species to a different genus-level taxon.
Here it is noted that the tarsometatarsus and the pedal phalanges of ?Dynamopterus anthracinus nov. comb. show a resemblance to the corresponding elements of Eleutherornis cotei from the middle Eocene (MP 14) of France and Switzerland. This species subsumes specimens that were before assigned to two species, Eleutherornis helveticus and “Diatryma” cotei, which were considered to be ratites and gastornithids, respectively. Mayr (2009a: p. 31) proposed that both species may be closely related and they were subsequently synonymized by Angst et al. (2013), who hypothesized that E. cotei is a European representative of the Phorusrhacidae. This latter classification was already doubted by Mayr (2017b) and here it is noted that the tarsometatarsus of E. helveticus more closely resembles that of ?D. anthracinus nov. comb. than that of phorusrhacids (compare Fig. 1(A, B, D) with Angst et al., 2013: fig.
4).

cf. Cariamiformes, gen. et sp. indet.
Fig. 1(I‒K)
Remarks: A tarsometatarsus (GMH XLI-23-1966; Fig. 1(I‒K)) lacking the trochleae metatarsorum II and IV resembles the tarsometatarsus of ?D. anthracinus nov. comb., but is from a significantly smaller species. The broken shaft of the bone exhibits a marked kink in is midsection, and with a reconstructed length of ca. 115 mm (189 mm in ?D. anthracinus nov. comb.) the specimen is longer than the tarsometatarsus of the following species, Strigogyps robustus (ca. 106 mm).

Cariamiformes incertae sedis
Ameghinornithidae Mourer-Chauviré, 1981
Strigogyps robustus (Lambrecht, 1935)
Fig. 2(A‒D, F)
Remarks: Lambrecht (1935) described two partial skeletons, consisting of wing/pectoral girdle elements (GMH 5884; Fig. 2(A)) and pelvis/hindlimb bones (GMH 5883; Fig. 2(B, D)), as species of the Bucerotidae (“Geiseloceros robustus”) and Cathartidae (“Eocathartes robustus”), respectively. Both fossils were found in close association in a Leichenfeld-type deposit of the Cecilie mine (MP 13). Mayr (2002a) maintained separation of two species and noted similarities of the wing elements to those of the Cariamiformes. Subsequently, however, Mayr (2007a) detailed that both G. robustus and E. robustus closely resemble Strigogyps sapea from Messel (Fig. 2(E)), and the species from the Geiseltal is now classified as Strigogyps robustus.
In the present study, two further fossils are assigned to S. robustus. One of these is a fragmentary tarsometatarsus (GMH XLI-328-1968; Fig. 2(C)). The other specimen is an isolated wing from the collection of NMB (formerly catalogued as GMH 4413; Fig. 2(F)). A distinctive feature of Strigogyps is the combination of a relatively long hand section of the wing with a greatly abbreviated ulna and radius (Mayr, 2007a). Similar wing proportions occur in wing-propelled divers, such as the Alcidae, but are unknown from other terrestrial birds.

 

[Fred Ruhe]

Systematic palaeontology -2

Apodiformes Peters, 1940
Aegialornithidae Lydekker, 1891
Aegialornis broweri Collins, 1976
Fig. 3(A‒C)
Remarks: A partial humerus (GMH L-9-1969; Fig. 3(A, B)) was assigned to Aegialornis broweri by Peters (1998). This apodiform species was originally described by Collins (1976) based on a humerus from an unknown locality of the Quercy fissure fillings in France, where aegialornithids only occur in Eocene strata (Mourer-Chauviré, 1988; Mayr, 2009a). Aegialornis broweri is decidedly smaller than Ae. gallicus, the largest and best known species of the Aegialornithidae, but it is distinctly larger than the putative aegialornithid Primapus lacki from the early Eocene (MP 8‒9) of the London Clay (Fig. 3(D, E)). Mlíkovský (2002) assigned the Geiseltal fossil to a new species, Aegialornis germanicus. This action was, however, poorly founded and GMH L-9-1969 closely agrees with Ae. broweri in size and morphology. Its original classification is therefore maintained in the present study.
GMH L-9-1969 lacks the proximal end and the breakage area allows a view in the interior of the bone. It has not been noted before that the fossil exhibits medullary bone (Fig. 3(C)), which indicates a breeding female.

?Falconiformes Sharpe, 1874
Masillaraptoridae Mayr, 2009b
cf. Masillaraptor parvunguis Mayr, 2006
Fig. 3(F, G)
Remarks: Mayr (2002a) tentatively referred a partial tarsometatarsus (GMH NW-XIV; Fig. 3(F, G)) to Coturnipes cooperi, a species described by Harrison and Walker (1977) from the early Eocene (MP 8‒9) of the London Clay. The Geiseltal tarsometatarsus was also compared with a fossil from Messel, which was subsequently described by Mayr (2006) as Masillaraptor parvunguis (Fig. 3(I)). This species is of uncertain phylogenetic affinities, but was likened to the Falconiformes (Mayr, 2009b). Mayr and Smith (2019a) identified a distal tarsometatarsus of Masillaraptor from the early Eocene (MP 8‒9) of Egem in Belgium (Fig. 3(K, L)). These authors detailed that an association of GMH NW-XIV with C. cooperi was erroneous, but maintained close affinities to M. parvunguis. The tarsometatarsi of the previously known specimens of M. parvunguis are poorly preserved (Fig. 3(I)) and do not allow detailed comparisons with GMH NW-XIV. In the course of the present study, however, a well-preserved isolated tarsometatarsus was identified
in the Messel collection of SMF, which closely matches GMH NW-XIV in size and morphology. This specimen (SMF-ME 1068; Fig. 3(H)) has a length of 39.8 mm and is therefore slightly longer than the tarsometatarsi of the two previously reported M. parvunguis skeletons, which measure ca. 33.5‒35.2 mm (Mayr, 2006).
Another tarsometatarsus from the Geiseltal (GMH 3060; Fig. 3(J)), which is here for the first time identified, exhibits a morphology similar to GMH NW-XIV, but is somewhat larger than the latter specimen. Whether the size differences found in the Geiseltal and the Messel fossils indicate different species or a sexual size dimorphism is unknown. It has not been noted so far that GMH NW-XIV also shows a resemblance to the much
smaller tarsometatarsus of Parvulivenator watteli from the early Eocene (MP 8‒9) of the London Clay (Fig. 3(M‒P)). P. watteli was described by Harrison (1982), who considered it to be a representative of the Falconidae. The species is only known from the holotype, a partial tarsometatarsus with associated phalanges.

Order incertae sedis
Halcyornithidae Harrison and Walker, 1972
Pseudasturides cf. macrocephalus and an undetermined species
Fig. 4(A‒G)
Remarks: Two partial tarsometatarsi of the Halcyornithidae were reported by Mayr (2002a). These fossils stem from two species which differ in the width of the tarsometatarsus shaft, with the shaft of GMH XVIII-3750-1957 (Fig. 4(A, B)) being more slender than that of GMH XIV-3823-1957 (Fig. 4(C‒E)). Halcyornithids are a common element in early Eocene avifaunas and are known from Messel, the London Clay, Egem in Belgium, and the North American Nanjemoy and Green River formations (Mayr, 2009a, 2016a, 2017b; Mayr and Smith, 2019a). GMH XIV-3823-1957 is from the Unterkohle and was tentatively referred to
Pseudasturides (“Pseudastur”) macrocephalus by Mayr (2002a); this latter species was originally described from Messel. GMH XVIII-3750-1957 is from the untere Mittelkohle (MP 12).
A newly identified mandible (GMH XLI-109; Fig. 4(F, G)) is here tentatively referred to the Halcyornithidae. The bone has dorsoventrally deep mandibular rami and closely resembles the mandible of halcyornithids from Messel (Mayr, 1998a) in its proportions. Being from the obere Mittelkohle (MP 13), GMH XLI-109 would be the youngest fossil record of the Halcyornithidae, if correctly identified.

Coliiformes Murie, 1872
Sandcoleidae Houde and Olson, 1992
Eoglaucidium pallas Fischer, 1987
Figs. 5(C‒EE), 6(C‒F)
Remarks: Eoglaucidium pallas was described by Fischer (1987), who referred seven humeri to the species, one of which (Fig. 5(A)) was erroneously considered to be from a juvenile individual and actually belongs to a different coliiform species. Here, nine further humeri of E. pallas are reported (Fig. 5(C‒P)). One of the humeri identified in the present study allows the recognition of medullary bone, which indicates a breeding female (Fig. 5(N, O)). Mayr (2002a) identified four coracoids of the species from the Geiseltal, to which seven further specimens are added in the present study (Fig. 5(U‒EE)). The bone is distinguished from the coracoid of the coliiform Coliidae in the presence of a foramen nervi supracoracoidei.
A fragmentary partial skeleton of E. pallas (GMH 4410; Fig. 6(E, F)) was already previously reported (Mayr, 2002a), but the collection of GMH also includes another, more complete albeit very poorly preserved articulated skeleton of E. pallas (GMH 1376/1377; Fig. 6(C, D)). This specimen is embedded in paraffin wax and may be identical to a fossil from “Leichenfeld II” (“carcass area II”) mentioned by Lambrecht in Weigelt (1932: p. 14) as “a pigeon-sized nearly complete bird with preserved skull, which may belong to an owl” (translated from the German text). The fossil includes tracheal rings, but osteological details are difficult to discern. An assignment to E. pallas is suggested by the overall size and proportions of the bone and coliiform characters include the short ulna and the shape of the carpometacarpus, which has a strongly bowed minor metacarpal. A counter part of one of the legs is preserved on a second slab, which is attached to the main specimen.
Stratigraphically, E. pallas occurs in the Unterkohle, untere Mittelkohle, and obere Mittelkohle, i.e., in strata from MP 11‒13. E. pallas is also well-represented in Messel (Mayr and Peters, 1998; Mayr, 2018b).

Coliidae Swainson, 1837
Selmes absurdipes Peters, 1999
Figs. 5(A, B), 6 (A, B)
Remarks: Another coliiform from the Geiseltal is much smaller than E. pallas and was assigned to Selmes absurdipes by Mayr (2001, 2002a), who identified a humerus of this species (GMH XXXVI-305-1963; Fig. 5(A)). In the present study, for the first time a coracoid is reported (GMH IL; Fig. 5(B)), which, unlike the coracoid of E. pallas, lacks a foramen nervi supracoracoidei.
A partial skeleton of S. absurdipes (GMH 1379; Fig. 6(A, B)) was mentioned by Mayr (2002a), but has not yet been figured. This specimen is embedded in paraffin wax and seems to be identical to a fossil from “Leichenfeld I” mentioned by Lambrecht in Weigelt (1932: p. 14) as “remains of a small bird without skull and neck, but with both legs complete until the claws, both scapulae, remains of the pelvis, both wings, and the pectoral girdle” (translated from the German text). Selmes absurdipes was originally described by Peters (1999) based on a fossil from Messel. The S. absurdipes specimens from the Geiseltal are from the Mittelkohle (MP 12 and 13).

Leptosomiformes Sharpe, 1891
Leptosomidae Blyth, 1838
Plesiocathartes geiselensis Mayr, 2002a
Fig. 7(A‒F)
Remarks: This species was described by Mayr (2002a) based on a proximal ulna, tibiotarsus, and tarsometatarsus of a single individual (GMH XXXV-559; Fig. 7(A‒F)). At this time, the taxon Plesiocathartes was only known from the Quercy fissure fillings, from Messel, and from the London Clay (Mayr, 2002b; Fig. 7(G, H)). Meanwhile, Plesiocathartes fossils were also reported from the North American Green River Formation (Weidig, 2006) and from the early Eocene (MP 8‒9) of Egem in Belgium (Mayr and Smith, 2019a; Fig. 7(I, J)). A tentative record exists from the late Paleocene of France (Mayr and Smith, 2019b). Mayr (2002b) tentatively assigned Plesiocathartes to the Leptosomiformes, which include a single extant
species that occurs on Madagascar and nearby islands. This classification has subsequently been corroborated (Weidig, 2006; Mayr, 2008, 2009).

?Leptosomiformes Sharpe, 1891
Gen. et sp. indet.
Fig. 7(K, M)
Remarks: A coracoid and a scapula on a lacquer sheet (GMH 4401; Fig. 7(K)) are reported here for the first time and may be from a leptosomiform bird, but are too small for Plesiocathartes geiselensis. The coracoid exhibits a distinctive morphology with an excavated cotyla scapularis and a well-developed crista procoracoidea and closely resembles the coracoid of P. major from the North American Green River Formation (Fig. 7(L)). However, GMH 4401 is smaller than the coracoid of P. major, with this latter species itself having a smaller size than P. geiselensis (tarsometatarsus length is 40.8 mm in P. geiselensis, but only 27 mm in P. major; Weidig, 2006). If GMH 4401 is from a leptosomiform bird, it is therefore from a smaller species than P. geiselensis. A previously unreported “roller-like” skull in the collection of NMB (formerly GMH 4412; Fig. 7(M)) may also belong to the Leptosomiformes, but is too poorly preserved for a definitive assignment.

 

[Fred Ruhe]

Systematic palaeontology -3

Bucerotiformes Fürbringer, 1888
Messelirrisoridae Mayr, 1998
Messelirrisor sp.
Fig. 4(H‒J, M)
Remarks: A partial humerus lacking the proximal end (GMH L-9-1969; Fig. 4(H‒J)) was assigned to the Messelirrisoridae by Mayr (1998b), but so far only a drawing of the mirrored bone has been published (Mayr, 1998b: fig. 10(C)). Here, a photograph of the fossil is for the first time shown and a second specimen is identified. This latter fossil (GMH 4400; Fig. 4(M)) consists of the pectoral girdle and both wings. Even though fragmentary, the humeri correspond well with GMH L-9-1969 in size and morphology. The bucerotiform
Messelirrisoridae are abundantly represented in Messel (Mayr, 1998b; Fig. 4(K, L)) and represent the smallest birds identified in the Geiseltal so far.

Undetermined avian remains
Remarks: Aves indet. A. The isolated coracoid GMH IL-47-1969 (Fig. 8(A)) is characterized by a very narrow extremitas omalis. The bone shows a foramen nervi supracoracoidei and is from a bird the size of Eoglaucidium pallas. It is, however, distinguished from the latter species and other coliiform birds in the narrower and straighter omal extremity and cannot be referred to one of the above species.
Aves indet. B and C. A lacquer sheet in the collection of NMB contains two left coracoids and a few other bone fragments (Fig. 8(B‒D); specimen formerly catalogued as GMH 4379). These coracoids are of similar size, but exhibit different morphologies. One of the bones is unusually massive (Fig. 8(D)) and shows an at least superficial resemblance to the coracoid of the Nyctibiidae, which are represented in Messel by the taxon Paraprefica (Mayr, 2018a).
Aves indet. D. An uncatalogued coracoid in the collection of GMH (Fig. 8(E)) belongs to a medium-sized species and resembles the coracoid of coraciiform birds.
Aves indet. E. Another uncatalogued coracoid in the collection of GMH (Fig. 8(H, I)) exhibits a different morphology, with a wider shaft that forms a crista procoracoidei, and a concave cotyla scapularis. This bone corresponds to a species the size of Masillaraptor, but an unambiguous taxonomic assignment of the fossil is not possible.
Aves indet. F. An uncatalogued humerus in the collection of GMH (Fig. 8(F)) resembles the corresponding bone of Eoglaucidium pallas (Fig. 8(G)), but is somewhat larger, has a shorter crista deltopectoralis, and a smaller and more centrally situated fossa musculi brachialis.
Aves indet. G. The collection of GMH includes a glass plate onto which various small pieces of lacquer sheets with bones of small birds are mounted (GMH XXXIV; Fig. 8(J‒M)). These specimens appear to belong to different individuals and include a sternum (Fig. 8(M)), a coracoid (Fig. 8(J)), wing bones (Fig. 8(L)), and a partial tarsometatarsus (Fig. 8(K)). The coracoid measures 23 mm, the carpometacarpus has a length of 15 mm. The sternum exhibits four deep incisions in its caudal margin and resembles the sternum of the coraciiform Primobucconidae (compare Fig. 8(M) with Mayr et al., 2004: fig. 1(A)). The coracoid, however, differs from that of coraciiform birds in the wider shaft and the tarsometatarsus is also unlike that of coraciiform birds in that the trochleae metatarsorum II et IV are more strongly deflected. Since it is unknown which, if any, of the bones were found in association, a reliable classification of the fossil is not possible.
Aves indet. H (?Halcyornithidae). An isolated sternum of a small bird (GMH 4403) is characterized by a very long spina externa (Fig. 8(N)). This fossil is too large to belong to Messelirrisor and corresponds to a bird the size of Aegialornis broweri or the halcyornithid species. The Aegialornithidae lack a greatly elongated spina externa (Mourer-Chauviré, 1988), which is present in the Halcyornithidae (Mayr, 2007b). It is here considered well possible that GMH 4403 is from a halcyornithid species, but an unambiguous identification of
the fossil is not possible. Aves indet. I (?Coliiformes). A further isolated sternum (GMH IL-10-1969; Fig. 8(O)) is characterized by the fact that trabecula intermedia arises from the trabecula lateralis and probably belongs to a representative of the Coliiformes. In size, the bone would correspond to Eoglaucidium pallas. However, the fossil is mediolaterally wider than the sterna of other Sandcoleidae (Houde and Olson, 1992) and has larger processus craniolaterales.
Aves indet. J and K. GMH XXXVII-31-1964 shows an association of bones of two different individuals (Fig. 9(A)). The specimen includes a sternum with pectoral girdle bones, a partial pelvis, a left humerus, and a left tibiotarsus of a medium-sized bird (humerus length: 43.5 mm; tibiotarsus length: 55 mm), which are preserved in association with a tibiotarsus of a significantly larger bird (tibiotarsus length: 90 mm). The humerus resembles the humerus of Aves indet. F in size and morphology, but an unambiguous taxonomic allocation of GMH XXXVII-31-1964 is not possible. Clearly, however, the fossil does not seem to belong
to any of the above-mentioned species (the tibiotarsus of E. pallas measures 44.1‒49.6 mm and sandcoleid Coliiformes also differ in the lower carina sterni; the tibiotarsus of Plesiocathartes is shorter than the humerus; Mayr, 2016b). The larger tibiotarsus likewise does not fit in size to any of the above-described species.
Aves indet. L (?Halcyornithidae). An uncatalogued and previously unreported partial skeleton from an unknown Geiseltal locality in the collection of GMH (Fig. 9(B)) is from a small bird, the size of Aegialornis broweri and the two species of the Halcyornithidae. This fossil is poorly preserved, but the tibiotarsus is largely complete and has a length of 29 mm. In size, the bones correspond to the tibiotarsus of Pseudasturides macrocephalus, which measures 28‒30.6 mm (Mayr, 2016b). The Geiseltal fossil is furthermore characterized by abbreviated proximal pedal phalanges, which are also found in the Halcyornithidae. Unlike in the latter, however, the single ungual pedal phalanx preserved in the Geiseltal fossil is strongly curved and very robust. Abbreviated proximal phalanges also occur in apodiform birds. Of the Aegialornithidae from the Quercy fissure fillings in France, only the tibiotarsus of Ae. gallicus has been reported. With a length of ca. 33 mm, the Ae. gallicus tibiotarsus is slightly longer than the humerus, which measures 24.5‒27.2 mm (Mourer-Chauviré, 1988). The holotypical humerus of Ae. broweri measures 19.1 mm (Collins, 1976), so that a tibiotarsus length of 23.1‒25.8 mm would be expected, if limb proportions similar to Ae. gallicus are assumed. With a length of 29 mm, GMH L-9-1969 exceeds this range, and the preserved portion of the coracoid differs from the coracoid of the Aegialornithidae in that the processus
acrocoracoideus does not form a pronounced medial hook.
Aves indet. M. GMH 4404 includes bones of the left wing and pectoral girdle of a small bird (Fig. 9(C)). The coracoid resembles that of GMH XXXIV (Aves indet. G) in size and morphology. The humerus appears to have been comparatively short and has a welldeveloped tuberculum supracondylare dorsale, which is, however, much shorter than the processus supracondylaris dorsalis of Aegialornis broweri. The humerus is broken and allows the recognition of medullary bone, which indicates a breeding female.
Aves indet. N (?Eoglaucidium pallas). A slab containing scattered bones and bone fragments (GMH XXII-159-1961; Fig. 10) is of particular taphonomic interest, because the specimen includes three humeri and two left scapulae, so that the bones belong to at least two similar-sized individuals, which may or may not belong to the same species. The sizes of the humerus and coracoid correspond to E. pallas, but the fragmentary condition of the bones does not allow an unambiguous identification. The fossil is furthermore notable because it also includes small pieces of eggshell which are distributed over the slab.

Fred