New late Eocene and Oligocene plotopterid fossils from Washington State (1 Viewer)

[Fred Ruhe]

Gerald Mayr & James L. Goedert, in press

New late Eocene and Oligocene plotopterid fossils from Washington State (USA), with a revision of "Tonsala" buchanani (Aves, Plotopteridae)

Journal of Paleontology. Online edition.
doi:10.1017/jpa.2021.81

Abstract: New late Eocene and Oligocene plotopterid fossils from Washington State (USA), with a revision of “Tonsala” buchanani (Aves, Plotopteridae) | Journal of Paleontology | Cambridge Core

We report new specimens of the Plotopteridae from Washington State (USA), an area where these flightless seabirds underwent significant diversification during the late Eocene and Oligocene. To date, five plotopterid species from western Washington have been formally named. Specimens previously assigned to Tonsala buchanani Dyke, Wang, and Habib, 2011 belong to at least two, but probably even three, different species. One of these, the large-sized “Whiskey Creek specimen” from late Eocene deposits mapped as the Makah Formation, is the oldest known plotopterid and is here tentatively assigned to ?Klallamornis clarki Mayr and Goedert, 2016. Another specimen originally referred to T. buchanani is also likely to belong to a different species and is among the most substantial records for North American plotopterids. We formally transfer T. buchanani to the taxon Klallamornis and show that the only unambiguously identified specimen of the species—the holotype—is currently poorly diagnosed from Klallamornis abyssa Mayr and Goedert, 2016, which is from coeval strata of the Pysht Formation. Although the holotype of K. abyssa is larger than that of K. buchanani, there remains a possibility that plotopterids were sexually dimorphic in size. We describe the first ungual phalanx of a plotopterid, which is referred to K. buchanani, and report previously unknown elements of the large ?K. clarki and the first records of this species from the Lincoln Creek Formation. Current data indicate that plotopterids originated in the middle or late Eocene on islands off western North America, and we hypothesize that the radiation of these birds in the North Pacific Basin may have been related to the evolution of kelp forests.

Enjoy,

Fred

 

[Fred Ruhe]

Introduction

The Plotopteridae were penguin-like, flightless seabirds that inhabited the North Pacific Basin in the late Eocene and Oligocene and possibly survived into the middle Miocene.
Plotopterids were initially considered to be most closely related to the suliform Phalacrocoracidae (cormorants) and Anhingidae (anhingas; By contrast, Mayr (2005) hypothesized that these birds are the sister taxon of the Sphenisciformes (penguins), but subsequent analyses recovered plotopterids as the sister taxon of either the Phalacrocoracidae and Anhingidae (Smith, 2010) or a more inclusive clade including the Sulidae (gannets and boobies), Phalacrocoracidae, and Anhingidae (Mayr et al., 2015; see Mayr et al., 2021 for a more detailed discussion of the affinities of plotopterids).

Systematic Paleontology

Aves Linnaeus, 1758
Plotopteridae Howard, 1969
Tonsalinae Mayr and Goedert, 2018
Tonsala Olson, 1980

Type species.—Tonsala hildegardae Olson, 1980, by original designation.

Holotype.—USNM 256518: partial associated skeleton. Beach west of Murdock Creek, Clallam County, Washington; Oligocene, lower part of the Pysht Formation.

cf. Tonsala hildegardae Olson, 1980

Description and comparisons.—SMF Av 662 is the most complete scapula of a North American plotopterid described so far. The bone is, however, split in a transverse plane so that only internal structures are exposed. The tip of the acromion still appears to be hidden in the matrix. In its size and shape, SMF Av 662 corresponds well with the scapula of the T. hildegardae holotype and shows that the irregular margins of the scapular blade of the latter are due to postmortem damage, as already assumed in the original description (Olson, 1980).

Material.—SMF Av 662: left scapula, which is still preserved in a block of matrix ; from the Jansen Creek Member of the Makah Formation; collected by J.L.G. on 11 June 1999.

Measurement.—Length as preserved, 123.8 mm.

Remarks.—The tentative assignment of this fossil to T. hildegardae is based mainly on its small size. The specimen comes from the Makah Formation and is therefore somewhat older than the holotype of T. hildegardae from the Pysht Formation. The only other record of T. hildegardae from the Makah Formation is a coracoid, which was tentatively referred to the species by Mayr and Goedert (2016).

Fred


Figure 1. (1–3) cf. Tonsala hildegardae (SMF Av 662) left scapula compared with (4) a cast of the right scapula of the holotype (LACM 123791) and (5) the left scapula of gen. indet. sp. indet. A (UWBM 86871); in (3), the surrounding matrix was digitally removed. acr = acromion.
Scale bars = 20 mm.

 

[Fred Ruhe]

Klallamornis Mayr and Goedert, 2016

Type species.—Klallamornis abyssa Mayr and Goedert, 2016, by original designation.

Klallamornis buchanani (Dyke, Wang, and Habib, 2011), n. comb.

2011 Tonsala buchanani Dyke, Wang, and Habib, p. 2, fig. 2A–V.
2015 Tonsala buchanani;Mayr, Goedert, and Vogel, restricted to holotype UWBM 86875 only.
2016 “Tonsala” buchanani; Mayr and Goedert, fig. 1D.
2018 “Tonsala” buchanani; Mayr and Goedert, p. 52, fig. 2D.

Holotype.—Partial skeleton: UWBM 98975; both femora, proximal end of a tibiotarsus, three vertebrae, ribs, and other bone fragments. Beach west of Murdock Creek, Clallam County, Washington; Oligocene, lower part of the Pysht Formation.

Description and comparisons.—The fragmentary proximal end of the femur of the newly referred specimen SMF Av 663 consists of the caudal half of the proximal end of the bone. The fossil closely corresponds to the femur of the holotype of Klallamornis buchanani in size and morphology. It is smaller than the femur of the K. abyssa holotype (the width of which is estimated at 34–35 mm) and larger than that of the Olympidytes thieli holotype (which measures 28.6 mm). A referral to K. buchanani is also supported by the fact that the fossil is from the type locality and horizon of the species. As in K. buchanani, Tonsala hildegardae, and O. thieli, the distal margins of the facies articularis antitrochanterica and the facies articularis acetabularis form a distinct rim, whereas the distal portion of the facies articularis acetabularis smoothly merges into the femur shaft in Hokkaidornis abashiriensis Sakurai, Kimura, and Katoh, 2008 and the species of Copepteryx (see also Mori and Miyata, 2021). As in other plotopterids, the fovea ligamenti capitis is very pronounced.
SMF Av 663 also includes an ungual phalanx, which lacks a part of its dorsal section and the proximal tip (Fig. 2.12). Ungual phalanges of plotopterids have not been described previously. The bone has an ovate cross section, lacks a laterally open sulcus neurovascularis, and exhibits numerous neurovascular openings on its surface. It is markedly curved and very robust, and in its overall shape is more like the ungual phalanges of the Fregatidae (Fig. 2.13) and Anhingidae (Fig. 2.14) than those of the Sulidae (Fig. 2.15) and Phalacrocoracidae (Fig. 2.16). However, unlike in the Fregatidae and Anhingidae but as in the Phalacrocoracidae and Sulidae, the tuberculum flexorium is only weakly prominent and forms a lip-like transverse ridge rather than a true tubercle.

Material.—SMF Av 663: fragment of proximal end of right femur, fragmentary thoracic vertebra, and ungual phalanx (Fig. 2.8–2.12); from the lower part of the Pysht Formation west of Murdock Creek, regarded as late early Oligocene or early late Oligocene (Barnes and Goedert, 2001), or late but not latest Oligocene (Nesbitt et al., 2010); collected by J.L.G. on 26 June 1983.

Measurement.—SMF Av 663: proximal width of femur, 32.0 mm.

Remarks.—The holotype of Tonsala buchanani (UWBM 86875) is a partial skeleton consisting of both femora, the proximal end of a tibiotarsus (incorrectly labeled as UWBM86871 by Dyke et al., 2011, fig. 2T), three vertebra, ribs, and other bone fragments. Contrary to the statement of Dyke et al. (2011, p. 2), the specimen does not include the proximal end of a tarsometatarsus or a fibula; Dyke et al. (2011, fig. 2R) furthermore illustrated the right femur of T. buchanani without the associated head. Tonsala buchanani was not properly diagnosed because all the characters listed by Dyke et al. (2011) pertain to the humerus, coracoid, and carpometacarpus and can therefore not be assessed in the holotype, which does not include these bones. Although the “Whiskey Creek specimen” (UWBM 86869) was only tentatively referred to T. buchanani by Dyke et al. (2011, p. 6), the associated carpometacarpus was considered to have characters diagnostic for T. buchanani. The alleged differences of this carpometacarpus and that of T. hildegardae furthermore appear to be based on comparisons with the os carpi ulnare of the latter species (Mayr and Goedert, 2016). The humerus and coracoid referred to and used to diagnose T. buchanani belong to a specimen (UWBM 86871; Fig. 3) that is discussed in the following and likely represents a different
species. Whether the tarsometatarsus UWBM86870, which was referred to T. buchanani by Dyke et al. (2011), belongs to this species cannot be determined for sure; Goedert and Cornish (2002) thought it was referrable to the species represented by UWBM 86871 because of its size and because it was found in the same rock unit. All of this leaves only the femora (Fig. 2.1, 2.2), proximal tibiotarsus, and thoracic vertebrae (Fig. 2.17, 2.18) of the holotype as unambiguously identified material of T. buchanani.
Dyke et al. (2011, table 1) gave the distal width of the holotype femur of T. buchanani as 25.2mm, but this value is too small and may pertain to the width of the bone as it is preserved. The actual distal width of the complete bone is here estimated at approximately 30.5mm. With a length of 134.2mm (Dyke et al., 2011, table 1), the femur of T. buchanani is shorter than that of Klallamornis abyssa (Fig. 2.3–2.5), which measures about 143mm and has a distal width of about 34mm (Mayr and Goedert, 2016). Although the holotype of K. abyssa is therefore distinctly larger than that of T. buchanani, the magnitude of
this size difference falls within the intraspecific sexual size dimorphism of extant Phalacrocoracidae, in which the males are significantly larger than the females, with their limb bones measuring up to 120% the length of those of females (Fig. 2.6, 2.7).
The holotypes of both T. buchanani and K. abyssa are from the lower part of the Pysht Formation near Murdock Creek, and at present it is not possible to reliably differentiate both species on the basis of morphological features other than size. The femur of T. buchanani appears to have a straighter shaft than that of Klallamornis abyssa, and the caudal portion of the condylus lateralis seems to have a wider medial rim. However, these differences are not reliably diagnostic, and the possibility remains that Klallamornis abyssa is a junior synonym of
T. buchanani. Currently, however, we refrain from a formal synonymization and note that the preparation of two partial skeletons of similar-sized species from the Olympic Peninsula is pending, which may inform the osteology of these species. In any case, the femur of T. hildegardae is not as stout as that of T. buchanani, and we here transfer the latter species to the genus Klallamornis.

Fred


Figure 2. (1, 2) Left femur of the holotype of Klallamornis buchanani (UWBM 86875) in caudal view; in (2), the bone was coated with ammonium chloride and mirrored; the missing portion of the condylus medialis is indicated by the gray area. (3–5) Right femur of the holotype of Klallamornis abyssa in caudal view (SMFAv 610); in (4), the surrounding matrix was digitally removed, and the missing proximal end of the bone is indicated by the gray area; in (5), the bone was coated with ammonium chloride. (6, 7) Left femora (cranial view) of the extant Phalacrocorax carbo (Phalacrocoracidae) to illustrate the pronounced sexual size dimorphism in the length of the bone: (6) a female individual; (7) a male individual. (8, 9) Fragment of the proximal end of a right femur referred to K. buchanani (SMF Av 663): (8) caudal view; (9) medial view. (10, 11) Thoracic vertebra associated with SMFAv 663: (10) dorsal view; (11) cranial view. (12) Partial ungual phalanx associated with SMF Av 663 in lateral and plantar views; the arrow denotes an enlarged view of the bone. (13–16) Ungual phalanges of (13) Fregata magnificens (Fregatidae), (14) Anhinga anhinga (Anhingidae), (15) Morus bassanus (Sulidae), and (16) Phalacrocorax carbo (Phalacrocoracidae). (17, 18) Three thoracic vertebrae associated with the holotype of Klallamornis buchanani (UWBM 86875): (17) right lateral view; (18) cranial view. cdl = condylus lateralis; cdm = condylus medialis; fac = facies articularis acetabularis; fat = facies articularis antitrochanterica; flx = tuberculum flexorium; fvc = fovea costalis; psp = processus spinosus; ptv = processus transversus; pvt = processus ventralis; zcr = zygapophysis cranialis. Scale bars = 20mm (the same scale applies for [13–16]).

 

[Fred Ruhe]

Gen. indet. sp. indet. A (cf. Klallamornis or Olympidytes)

2002 Plotopteridae, new species?; Goedert and Cornish, p. 67, figs. 3b, 4b, 5d.
2011 Tonsala buchanani (in part); Dyke, Wang, and Habib, p. 2, figs. 2G–J, 2M, 2P–Q, 2U–V.
2018 “Tonsala” buchanani; Mayr and Goedert, fig. 2D.
2021 Plotopteridae, unidentified species; Mayr et al., p. 2,
fig. 3a.

Description and comparisons.—UWBM 86871 is the only plotopterid in which the humerus, coracoid, and femur of a single individual are preserved in their entire length. As such, the specimen is of significance for an assessment of the limb proportions of plotopterids, even though all three bones are broken in two or more parts that were shifted apart owing to tectonic movements during the fossilization process.
UWBM 86871 includes the cranial extremity of the left scapula, which has been freed of matrix, with a portion of the scapular blade still being appressed to the sternal end of the coracoid. The scapula was mentioned by Goedert and Cornish (2002) but not by Dyke et al. (2011), who stated that the bone is known only from the T. hildegardae holotype. As in other plotopterids, the scapula of UWBM 86871 has a very long acromion, which forms a sharper angle with the cranial margin of the bone than in T. hildegardae, in which the base of the acromion smoothly merges into the cranial margin of the scapula (Fig. 1.4, 1.5). The acromion of UWBM 86871 is less ventrally deflected than in a plotopterid from Japan (Ando and Fukata, 2018). The bone appears to be slightly larger than the scapula we refer to T. hildegardae in the present study (SMF Av 662; see the preceding notes). Dyke et al. (2011, p. 2) stated that the coracoid of UWBM 86871 consists of the “cranial [sic] end […] broken at the level of the sternocoracoid impression,” but the bone is completely preserved. The UWBM 86871 coracoid (Fig. 4.1) is distinctly smaller than the coracoid that was referred to Klallamornis
abyssa (Fig. 4.2) by Mayr and Goedert (2016). The fossil differs from the coracoid of the Tonsala hildegardae holotype in that the facies articularis clavicularis does not form a pronounced hook. It is distinguished from the coracoid SMF Av 614, which was referred to Tonsala sp. by Mayr and Goedert (2016), in that the processus procoracoideus more strongly points in the omal direction. The sternal extremity of UWBM 86871 is too poorly preserved for close comparison with other plotopterids. Apart from being smaller, the coracoid of UWBM 86871 resembles that of the recently described Stenornis kanmonensis Ohashi and Hasegawa, 2020 from the early
Oligocene of Japan (Ohashi and Hasegawa, 2020). However, since the coracoids of other similar-sized taxa, such as Olympidytes thieli, are unknown, it is not possible to assess the phylogenetic significance of this resemblance. Ohashi and Hasegawa (2020, p. 288) did not list measurements for the length of the Stenornis kanmonensis coracoid but noted that “the size is almost the same as Copepteryx hexeris,” for which the length of the coracoid was given as 180 mm by Olson and Hasegawa (1996). With an estimated length of ∼150 mm, the coracoid of UWBM 86871 is distinctly shorter.
The humerus of UWBM 86871 and the referred humerus SMF Av 650 are the only completely preserved humeri of plotopterids from the Olympic Peninsula discovered so far. The shaft of the bone shows a marked sigmoid curvature, which is characteristic of the plotopterid humerus. It is more slender than the humerus shaft of Copepteryx hexeris Olson and Hasegawa, 1996, the only other plotopterid species for which a complete humerus is known. The shaft is not as strongly bulging dorsally as it is in the T. hildegardae holotype, a condition that was considered of pathologic origin by Olson (1980). The distal end of the bone resembles the humerus of T. hildegardae in the dorsoventrally narrow process flexorius. As detailed by Goedert and Cornish (2002), however, the trochlear ridges are better developed than in the T. hildegardae holotype.
The ulna (Fig. 3.7) is broken in two portions and lacks the intermediate section. The proximal end of this bone was previously illustrated by Dyke et al. (2011, fig. 2M) but misidentified as the proximal radius. As far as comparisons are possible, the preserved portions of the bone resemble the ulna of T. hildegardae (Olson, 1980; Mayr et al., 2015).
Dyke et al. (2011, p. 2) stated that the femur of UWBM 86871 was “glued together in the UWBM collection back-tofront.” However, and as noted by Mayr and Goedert (2016), the bone has merely been freed from surrounding rock and is in the same state it was in the original matrix.

Material.—UWBM 86871: partial skeleton including the left coracoid, left scapula, left humerus (erroneously stated to be from the right side by Dyke et al., 2011, p. 2 but correctly labeled as a left humerus by Dyke et al., 2011, fig. 2I–J; Dyke et al., 2011 also listed the distal end of a left humerus, but UWBM 86871 includes only the left humerus, which is complete), partial left ulna (erroneously identified as the radius by Dyke et al., 2011), and left femur; from the Jansen Creek Member of the Makah Formation, southeast of Bullman Creek. SMF Av 650: right humerus (Fig. 3.10); from the Jansen Creek Member of the Makah Formation, approximately 200 meters west of the mouth of Rasmussen Creek; collected by JLG on 27 December 1986. The Jansen Creek Member is an olistostrome and latest Eocene to earliest Oligocene in age.

Measurements.—UWBM 86871: humerus, length as preserved, 143.8 mm (Dyke et al., 2011, table 1), distal depth, 16.1 mm; coracoid, length as preserved, ∼150 mm; femur, length as preserved, 133.0 mm (Dyke et al., 2011, table 1 erroneously listed the femur measurements for UWBM 86870, which is an isolated tarsometatarsus). SMF Av 650: humerus, maximum length along longitudinal axis, 136.0 mm; width of shaft in midsection, 20.0 mm; maximum proximal width, 33.0 mm; maximum distal width, 28.6 mm.

Remarks.—UWBM 86871 was referred to Klallamornis buchanani by Dyke et al. (2011) and is much more complete than the holotype of this species. As preserved, the length of the femur of UWBM 86871 is subequal to that of the K. buchanani holotype (135.1 versus 133.0 mm; Fig. 4.7, 4.9), but the bone is broken in the distal section of the shaft, and the two portions are shifted apart by some distance. It was, therefore, originally shorter than the femur of the Klallamornis buchanani holotype (Fig. 4.8), from which it also differs in having a narrower proximal end (28.3 versus 33mm; Fig. 4.12, 4.13). The condylus lateralis of UWBM 86871 is furthermore narrower than that of the K. buchanani holotype.
Apart from being larger, UWBM86871 differs from Tonsala hildegardae in the shape of the processus acrocoracoideus of the coracoid, which has a bulkier tip and forms a less-pronounced hook (Fig. 4.3, 4.5); the acromion of the scapula forms a sharper angle with the cranial margin of the bone (Fig. 1.4, 1.5); the shaft of the femur is stouter than in T. hildegardae.
UWBM 86871 is distinctly smaller than specimens assigned to Klallamornis abyssa, and the femur is longer than that of the Olympidytes thieli holotype (Fig. 4.11). A well-founded assignment to Klallamornis or Olympidytes, or a delimitation from either taxon is, however, not possible currently.

Fred


Figure 3. (1–9) Major bones of the plotopterid specimen UWBM 86871 from the Makah Formation (gen. indet. sp. indet. A), which was previously assigned to, and in part used to diagnose (incorrectly), Tonsala buchanani by Dyke et al. (2011). (1, 2) Left coracoid: (1) dorsal view; (2) ventral view. (3) Cranial portion of the left scapula in lateral view. (4–6) Left humerus: (4) cranial view; (5) caudal view; (6) caudoventral view. (7) Proximal and distal portions of left ulna. (8, 9) Left femur: (8) caudal view; (9) cranial view. (10) Right humerus, which is here assigned to the same indeterminate species (SMFAv 650). acr = acromion; fac = facies articularis clavicularis; ppc = processus procoracoideus; scp = portion of scapular blade; tbd = tuberculum dorsale. Scale bars = 20 mm.

Figure 4. Selected bones of specimen UWBM 86871 (gen. idet. sp. indet. A) compared with other plotopterids. (1) Left coracoid of UWBM 86871 in dorsal view. (2) Right coracoid (UWBM 108400; dorsal view), which was assigned to Klallamornis abyssa by Mayr and Goedert (2016). (3, 4) Omal extremity of the left coracoid of UWBM 86871: (3) dorsomedial view; (4) medial view. (5) Omal extrmity of the coracoid of Tonsala hildegardae in dorsomedial view (cast of the holotype, LACM 123791). (6) Omal extremity of the coracoid of Plotopterum joaquinensis, earliest Miocene, California, in medial view (holotype, LACM 8927). (7, 8) Left femur of UWBM 86871; in (8) the bone was digitally brought to its presumed original length. (9) Left femur of Klallamornis buchanani (holotype, UWBM 86875). (10) Left femur of Tonsala hildegardae (UWBM 86873). (11) Left femur of Olympidytes thieli (cast of holotype, SMF Av 608; coated with ammonium chloride). (12, 13) Details of the proximal ends (caudal view) of the femora of (12) UWBM 86871 and (13) K. buchanani (holotype, UWBM 86875). hkp =
hook-like projection formed by processus acrocoracoideus; pac = processus acrocoracoideus; ppc = processus procoracoideus.
Scale bars = 20 mm.

 

[Fred Ruhe]

?Klallamornis clarki Mayr and Goedert, 2016

2002 New genus and species?; Goedert and Cornish, p. 67, fig. 3c.
2009 “unnamed species”; Mayr, p. 68, fig. 7.4a.
2016 ?Klallamornis clarki Mayr and Goedert, p. 9, figs. 7A–F, 8A–E.
2018 ?Klallamornis clarki; Mayr and Goedert, p. 54, fig. 2E.

Holotype.—LACM 129405: tarsometatarsus; Jansen Creek Member of the Makah Formation, Clallam County, Washington; latest Eocene or earliest Oligocene.

Description and comparisons.—Apart from being much larger, the humerus shows a close similarity to the proximal humerus of Tonsala hildegardae (Olson, 1980; Goedert and Cornish, 2002) and to that of UWBM 86871. It also resembles the proximal humerus of Copepteryx hexeris (only a small fragment of the proximal humerus of Hokkaidornis
abashiriensis is known). The globose caput humeri protrudes slightly farther ventrally than the tuberculum ventrale (the latter is, however, damaged in both humeri of SMF Av 664). The tuberculum dorsale is proximodistally long, but its distal end does not reach farther distally than the crista bicipitalis. The distal margin of the sulcus transversus forms a cranially protruding ledge. On the caudal surface, distal of the fossa pneumotricipitalis, is a marked tubercle for the attachment of musculus latissimus dorsi, pars cranialis (Fig. 5.5).
The ventral rim of the facies articularis caudalis of the thoracic vertebra preserved in SMFAv 664 forms a distinct, caudally directed lip-like process (Fig. 5.10).We also refer to ?K. clarki a thoracic vertebra also from the lower part of the Lincoln Creek Formation along the middle fork of the Satsop River, which was figured by Goedert and Cornish (2002, fig. 5a, b).

Material.—SMF Av 664: proximal ends of left and right humeri as well as a fragmentary thoracic vertebra (Fig. 5.1–5.5, 5.9, 5.10); float concretion from the lower part of the Lincoln Creek Formation (late Eocene or earliest Oligocene), gravel bar on west side of the middle fork of the Satsop River; collected by J.L.G. on 30 June 2017. SMF Av 665: shaft section of right humerus (Fig. 5.6); from the Jansen Creek
Member of the Makah Formation, float from terrace approximately 1,100 m southeast of Bullman Creek; collected by J.L.G. on 11 May 2012. UWBM 86872: thoracic vertebra; from the Lincoln Creek Formation, collected by J.L.G.

Measurements.—Humerus (SMF Av 664), maximum proximal width, 56.2 mm; estimated total length, ∼210–220 mm.

Remarks.—?Klallamornis clarki is the largest plotopterid species from the Olympic Peninsula and approaches the size of the very large Oligocene species Copepteryx hexeris and Hokkaidornis abashiriensis from Japan (Fig. 6). Its large size clearly distinguishes ?K. clarki from all other plotopterids from North America. Its genus-level assignment, however, is uncertain, because the known specimens have no skeletal elements in common with the fossils assigned to K. abyssa and i.K. buchanan
The previously known material of ?K. clarki consisted of only the holotype, a tarsometatarsus (LACM 129405; Fig. 6.8–6.11), and a partial pelvis (Fig. 6.1, 6.2), which were described by Mayr and Goedert (2016).

Fred


Figure 6. Comparison of selected elements of ?Klallamornis clarki and Hokkaidornis abashiriensis. (1, 2) Partial pelvis of ?Klallamornis clarki (SMF Av 612) from the Jansen Creek Member of the Makah Formation in right and left lateral views; the fossa that is situated caudal of the foramen acetabuli distinguishes the specimen from the pelvis of Hokkaidornis abashiriensis. (3) Pelvis of H. abashiriensis in right lateral view (SMF, cast of holotype); the frame indicates the position of the portion preserved in SMFAv 612. (4–7) Right tarsometatarsus of H. abashiriensis (SMF, cast of holotype): (4) plantar view; (5) dorsal view; (6) distal view; (7) proximal view. (8–11) Left tarsometatarsus (holotype, LACM 129405) of ?K. clarki from the Jansen Creek Member of the Makah Formation: (8) plantar view; (9) dorsal view; (10) distal view; (11) proximal view. (12, 13) Partial right tarsometatarsus from the Jansen Creek Member of the Makah Formation (SMFAv 609), which was tentatively referred to Olympidytes thieli by Mayr and Goedert (2016): (12) plantar view; (13) dorsal view; coated with ammonium chloride. In (4, 6, 8, 10, 12), the tarsometatarsal trochleae are numbered. cht = crista hypotarsi; fdl = sulcus for tendon of musculus flexor digitorum longus; fos = fossa caudal of foramen acetabuli; inc = incisura intertrochlearis lateralis; sul = sulcus between trochlea metatarsi III and IV. Scale bars = 20 mm.

 

[Fred Ruhe]

cf. ?Klallamornis clarki
(“Whiskey Creek specimen”)

2002 New genus and species(?), theWhiskey Creek specimen; Goedert and Cornish, p. 68, figs. 4c, 5c.
2009 “Whiskey Creek specimen”; Mayr, p. 68, fig. 7.4b.
2011 Tonsala buchanani (in part); Dyke, Wang, and Habib, p. 2, figs. 2A, B, F, K, L, N, O.
2021 cf. Klallamornis; Mayr et al., p. 2, figs. 1a, 1h, 3m.

Description and comparisons.—Mandible (Fig. 7.1, 7.2) and pterygoid (Fig. 7.3) of UWBM 86869 were already described and compared with stem group Sphenisciformes and extant Suliformes by Mayr et al. (2021). As detailed by Mayr et al. (2015), an alleged pterygoid figured by Dyke et al. (2011, fig. 2A) is a vertebra.
Of the coracoid, only the portion around the cotyla scapularis is visible, which is still unprepared and partly embedded in matrix (Fig. 7.5). The processus procoracoideus appears to be proportionally longer than in specimens referred to Klallamornis abyssa (Mayr and Goedert, 2016).
Of the furcula, the right extremitas omalis is preserved and was listed by Goedert and Cornish (2002) but not mentioned by Dyke et al. (2011). The bone exhibits a large articular facet for the coracoid and a long but narrow processus acromialis (Fig. 7.4).
UWBM 86869 includes the distal end of the left humerus, which closely resembles the distal humerus of Copepteryx hexeris in its morphology. Unlike in T. hildegardae and UWBM 86871, the ventrodistal portion of the bone is broadly rounded (Fig. 7.8, 7.9). As already noted by Goedert and Cornish (2002), the trochlear ridges are furthermore better developed than in Tonsala hildegardae. The dorsal trochlear ridge, which borders the sulcus humerotricipitalis, forms a ventrally directed
projection. In distal view, however (Fig. 7.13, 7.14), the intermediate
trochlear ridge of UWBM 86869 is less prominent than in UWBM 86871 and is directed toward the ventral trochlear ridge, rather than being positioned parallel to it as inUWBM 86871, C. hexeris, and H. abashiriensis.
Although Dyke et al. (2011, p. 6) stated the carpometacarpus of UWBM 86869 was an incomplete proximal portion, the bone is nearly complete (Goedert and Cornish, 2002, fig. 5c; Dyke et al., 2011, fig. 2N, O; herein Fig. 7.15, 7.16). The specimen closely resembles the carpometacarpi of Hokkaidornis abashiriensis (Fig. 7.17) and Copepteryx hexeris in its proportions. However, it exhibits a better-developed processus pisiformis than the carpometacarpus of H. abashiriensis, and the os metacarpale alulare is proportionally shorter than in H. abashiriensis and C. hexeris, with its proximal margin being more clearly offset from the carpal trochlea.

Material.—UWBM 86869: caudal portion of left mandibular ramus, right pterygoid, right extremitas omalis of furcula, distal end of left humerus, left carpometacarpus (Fig. 7), and a vertebra; from late Eocene (35.3–34 Ma) strata of the Makah Formation west of Whiskey Creek (see Goedert and Cornish, 2002).

Measurements.—Carpometacarpus, length, 67.0 mm (Dyke et al., 2011, table 1).

Remarks.—As detailed by Goedert and Cornish (2002), this specimen is from rocks mapped as the Makah Formation west of Whiskey Creek (mapped in error as the Pysht Formation by Nesbitt et al., 2010; E.A. Nesbitt, personal communication, 2011) and is possibly the oldest North American plotopterid; Phocavis maritimus is from strata nearly the same age. The Whiskey Creek specimen was tentatively referred to
Klallamornis (“Tonsala”) buchanani by Dyke et al. (2011, p. 6), but it clearly represents a species that had a much larger size than K. buchanani.
As detailed by Goedert and Cornish (2002), UWBM86869 distinctly differs in the shape of the distal end of the humerus from UWBM 86871, another specimen originally referred to and used in part to diagnose Klallamornis (“Tonsala”) buchanani by Dyke et al. (2011). Apart from differences in the size and orientation of the trochlear ridges (see Goedert and Cornish, 2002: fig. 4 [the specimen in fig. 4e is the holotype of H. abashiriensis]), UWBM 86869 has a less-protruding
and more-rounded processus flexorius than UWBM 86871 (Fig. 7.8, 7.9, 7.12). UWBM 86869 is also clearly distinguished from Tonsala hildegardae and Hokkaidornis abashiriensis in the morphology of the distal end of the humerus. The carpometacarpus of UWBM 86869 furthermore differs from that of Copepteryx and Hokkaidornis in the better-developed processus pisiformis (Fig. 7.15, 7.17).
Our tentative assignment of UWBM 86869 to ?K. clarki is based on the very large size of the fossil. There are, however, no skeletal elements in common between UWBM 86869 and definitive specimens of ?K. clarki. Compared with the holotype of Hokkaidornis abashiriensis, definitive ?K. clarki specimens are only slightly smaller, and UWBM 86869 is also slightly smaller than what would be expected for the sizes of the arpometacarpus and distal humerus of ?K. clarki. Whether this size
difference is due to sexual dimorphism or the older geological age of the fossil, or whether it is indicative of species-level differences, cannot be said.

Fred


Figure 7. The Whiskey Creek specimen UWBM 86869 (cf. ?Klallamornis clarki). (1, 2) Caudal portion of left mandible of UWBM 86869: (1) dorsal view; (2) dorsomedial view. (3) Right pterygoid of UWBM 86869. (4) Right extremitas omalis of furcula of UWBM 86869. (5) Fragmentary portion of the omal extremity of the left coracoid of UWBM86869 in dorsal view. (6) Omal extremity of left coracoid ofUWBM86871 (gen. indet. sp. indet. A) in dorsal view. (7) Omal extremity of a right coracoid referred to K. abyssa (UWBM 108400; dorsal view). (8, 9) Distal end of the left humerus ofUWBM86869: (8) cranial view; (9) caudal view. (10, 11) Distal end of the left humerus of Hokkaidornis abashiriensis (SMF cast of holotype): (10) cranial view; (11) caudal view. (12) Distal end of the left humerus of UWBM 86871 (gen. indet. sp. indet. A) in caudal view. (13, 14) Distal ends (distal view) of the left humeri: (13) UWBM 86869; (14) UWBM 86871 (gen. indet. sp. indet. A). (15, 16) Left carpometacarpus of UWBM 86869: (15) ventral view; (16) dorsal view. (17) Right carpometacarpus (ventral view) of H. abashiriensis
(SMF cast of holotype). cdd = condylus dorsalis; cdv = condylus ventralis; csc = cotyla scapularis; dtr = dorsal trochlear ridge; faa = facies articularis acrocoracoidea; flx = processus flexorius; htp = sulcus humerotricipitalis; itr = intermediate trochlear ridge; oma = os metacarpale alulare; pac = processus acromialis; pis = processus pisiformis; pmd = processus medialis; ppc = processus procoracoideus; stp = sulcus scapulotricipitalis; vtr = ventral trochlear ridge.
Scale bars = 20 mm.