Dynatoaetus pachyosteus sp. nov. (1 Viewer)

[Fred Ruhe]

Ellen K. Mather, Michael S. Y. Lee, Diana A. Fusco, John Hellstrom, and Trevor H. Worthy, 2023

Pleistocene raptors from cave deposits of South Australia, with a description of
a new species of Dynatoaetus (Accipitridae: Aves): morphology, systematics and
palaeoecological implications

ALCHERINGA: AN AUSTRALASIAN JOURNAL OF PALAEONTOLOGY 1–32. doi:10.1080/03115518.2023.2268780. ISSN 0311-5518

Abstract and free pdf: https://www.tandfonline.com/doi/full/10.1080/03115518.2023.2268780

The Pleistocene fossil record of Australian raptors (Accipitridae: eagles, hawks and Old World vultures) is very poorly understood with only three distinct extinct species confirmed until now. The small Necrastur alacer remains unstudied; however recent research has established Cryptogyps lacertosus as a valid species that, along with the very large Dynatoaetus gaffae, has potential affinities with the Aegypiinae–Circaetinae clade. These, along with a single large living inland raptor, the Wedge-tailed Eagle Aquila audax, suggest that Australia had an impoverished diversity of large raptors compared to other similar continental regions. However, fossil material similar in size to A. audax from multiple Pleistocene cave deposits raises the possibility of further taxa and is here assessed. A partial skeleton from Green Waterhole/Fossil Cave in the Tantanoola District of South Australia is referred to Cryptogyps lacertosus on the basis of similar size to bones of this species and that the associated coracoid is identical to that found with a tarsometatarsus that was previously referred to this species, coming from Leaena’s Breath Cave on the Nullarbor Plain, Western Australia. This partial skeleton allowed additional material from the Old Collections, Wellington Caves, and Walli Caves in New South Wales to be referred to this species. A second species, more robust than A. audax, is identified from material from Victoria Fossil Cave at Naracoorte. Phylogenetic analyses determined this species to be the sister taxon of the much larger Dynatoaetus gaffae recently described from several Australian sites, and so we name it as Dynatoaetus pachyosteus sp. nov. Further fragmentary remains attributable to either A. audax, C. lacertosus or D. pachyosteus are recorded from sites in the Wellington Caves complex, NSW. This study increases the known diversity of raptors in Pleistocene Australia, consistent with the presence of the more diverse megafaunal prey that existed at the time.

Enjoy,

Fred

 

[Fred Ruhe]

Systematic palaeontology

Order ACCIPITRIFORMES Vieillot, 1816
Family ACCIPITRIDAE Vigors, 1824
Cryptogyps lacertosus (de Vis, 1905)

Synonyms
1905, Taphaetus lacertosus de Vis, pl. 1, fig. 1.
1974, Taphaetus lacertosus de Vis; van Tets, p 58.
2022, Cryptogyps lacertosus (de Vis); Mather et al., p 8.

Diagnosis
Cryptogyps lacertosus is diagnosed by characters of the humerus and tarsometatarsus described in Mather et al. (2022). We add to those here to include the following characters: a coracoid where the width of the cotyla scapularis is less than a quarter of the shaft width, the processus coracoideus has little medial projection and little ventral curvature, and the shaft is broad relative to its length; a scapula with little expansion in width distally, and strong ventral curvature distally; an ulna with a markedly flattened dorsal facies along the shaft length, a non-pneumatic fossa present caudodorsal of the cotyla ventralis; a carpometacarpus where the distal end of the ventral trochlear rim is proximal of the processus pisiformes.

Referred material
SAMA P24329 fragmented thoracic vertebra; SAMA P53845 near complete right scapula, with only the distal end worn away; SAMA P42487 almost complete right coracoid with only the facies articularis clavicularis, processus acrocoracoideus and processus lateralis worn away; SAMA P24324 complete right ulna; SAMA P24323 complete left ulna; SAMA P24326 complete right radius; SAMA P24325 complete left radius; SAMA P24328 complete right carpometacarpus; SAMA P24327 complete left carpometacarpus; SAMA P53845 complete os metatarsale I. This material is referred to C. lacertosus first because the coracoid is identical to that found in Leanna’s Breadth Cave, which was in turn associated with a distinctive tarsometatarsus that was referred to this species by Mather et al. (2022). Second, these bones represent a similar sized bird to that represented by the lectotype distal humerus and other referred material for C. lacertosus (see Mather et al. 2022) and differ from Aquila audax and the other similar sized species described below. WAM 15.9.73 proximal left tarsometatarsus (see Mather et al. 2022). WAM 15.9.72 right coracoid missing omal end. AM F129566 distal right ulna. AM F54723 distal right ulna.

Locality, unit and age
SAMA P24329, SAMA P53845, SAMA P42487, SAMA P24324, SAMA P24323, SAMA P24326, SAMA P24325, SAMA P24328, SAMA P24327 derive from Site 7, Green Waterhole/Fossil Cave, 37�440S; 140�310E. Tantanoola district, South Australia, Australia. SAMA P53845 was recovered from the area encompassed by the grid C5–C6/N5–N6 (Fig. 2). Nearly all the vulture bones were found within a deposit of cave rafts with little terrigenous matter. Cave rafts form evaporatively on the surface of a pool in a cave so, when the fossils were deposited, they fell into a pool that was in the lower reaches of the chamber when this area of the cave was above the water table. The Uranium series dates obtained from calcite cave rafts reveal they formed in a narrow time interval 61.1–59.1ka. This is consistent with deposition during the marine lowstand in Marine Isotope Stage 4, when global sea levels were �80m lower than present ones (Miller et al. 2020) and the water table in the limestone housing the cave will have dropped accordingly. Rising sea levels commencing in the latest Pleistocene submerged the former pool and the surrounding slopes in and on which the fossils were deposited.
WAM 15.9.73 and WAM 15.9.72 were recovered from Leaena’s Breath Cave, Nullarbor, Western Australia, Australia, 31.4�S 128.1�E. WAM 15.9.73: Pit B1, Unit 3, depth 115–120cm; WAM 15.9.72: Pit B, Unit 3, Quadrat 5, 100–105cm depth, Early Pleistocene; collected by G. Prideaux in 2013, reported by E. Shute (2018).
AM F129566, no locality or stratigraphy data, however recorded as from Wellington Caves, New South Wales, Australia.
AMF 54723 was collected in 1966 or 1967 by R. M. Frank from Walli Caves, 27km northeast of Cowra, in Wellington Valley, New South Wales, Australia.

Remarks
The new material of Cryptogyps lacertosus differs from Aquila audax in the following characters (A. audax in brackets): the wing bones are notably more robust in C. lacertosus. Ulna: the dorsal facies is greatly flattened (rounded); the tuberculum ligamentosa collateralis ventralis is barely prominent and does not extend ventrally past the cotyla ventralis rim (ventrally prominent and extends past the cotyla rim); the fossa caudodorsal of the cotyla ventralis is inset into the cotyla facet (positioned adjacent to cotyla rim); the olecranon has little proximal projection to the cotyla ventralis (prominent projection); the dorsal margin of the dorsal condyle form a notable angle of approximately 70�relative to the shaft (very slight angle, 80�þ). Carpometacarpus: the processus extensorius has little proximal projection (notable proximal upturn); the distal end of the ventral trochlear rim is proximal of the base of the processus pisiformis and well proximal of the processus alularis (adjacent with); the os metacarpale minus is arched towards the caudal end (largely flat). Scapula: the facies articularis clavicularis has extreme lateral prominence and distinctly overhangs the lateral facies (slight prominence); a large, deep pneumatic fossa is present in the medial face (absent); the corpus scapulae weakly expands in width distally (notably expands). Radius: the tuberculum bicipitalis radialis is largely flat and does not extend beyond the cotyla humeralis margin (peaked, prominently extends past margin); the tuberculum aponeurosis ventralis is less prominent ventrally (more prominent); the facies articularis ulnaris is dorsoventrally compressed (not compressed). Coracoid: the foramen n. supracoracoidei is set adjacent to the shaft corpus (set close to the medial margin of the processus procoracoideus); the foramen has a medial opening into the corpus (absent); the cotyla scapularis is less than a quarter the size of the facies articularis humeralis and is shallow (quarter of facies size, deep); the margin of the processus procoracoideus slopes sternomedially to the cotyla scapularis (consistently level with cotyla).
While some generic differences between C. lacertosus and D. gaffae have already been established (see Mather et al. 2023), the new C. lacertosus material reveals further differences from D. gaffae (character state in brackets) notably in the following ways. Ulna: the tuberculum carpale is strongly projecting (weakly projecting). Carpometacarpus: the ventral rim of the trochlea carpalis terminates well proximal of the processus pisiformes (adjacent to) Scapula: a pneumatic foramen is present in the base of the acromion in proximal view (absent), the distal margin of the facies articularis humeralis projects outwards from the shaft margin (continuous with shaft margin).

Fred


Fig. 1. Humeri (A–D), carpometacarpi (E–H) and radius (I, J) of eagle-sized accipitrids from Australia. Dynatoaetus pachyosteus. Holotype left humerus SAMA P41517 in A, caudal and B, cranial view, extant Aquila audax left humerus FUR 125 in C, cranial and D, caudal view, E, Dynatoaetus gaffae left carpometacarpus in ventral view, Cryptogyps lacertosus left carpometacarpus (Green Waterhole) in F, ventral and G, dorsal view; D. pachyosteus carpometacarpus from Victoria Fossil Cave in H, ventral view, C. lacertosus (Green Waterhole) radius in I, ventral and J, dorsal view. Abbreviations: CB, crista bicipitalis; CD, crista deltopectoralis; CH, cotyla humeralis; CV, condylus ventralis; DL, depressio ligamenti; DR, depressio radialis; DSH, dorsal sulcus humerotricipitalis; FADMaj, facies articularis digitalis major; FADMin, facies articularis digitalis minor; FAH, facies articularis humeralis; FAR, facies articularis radialis; FAU, facies articularis ulnaris; FB, fossa brachialis; FI, fossa infratrochlearis; FO, fossa olecrani; FPV, fossa pneumaticum ventralis; FS, fossa supratrochlearis; IC, incisura capitis; MPS, m. pectoralis scar; MSC, insertion of m. scapulohumeralis cranialis; OMM, os metacarpale minus; PA, processus alularis; PE, processus extensorius; PF, processus flexorius; PP, processus pisiformis; SLT, sulcus lig. transversus; SNC, sulcus nervi coracobrachialis; ST, sulcus tendineus; TAV, tuberculum aponeurosis ventralis; TBR, tuberculum bicipitalis radialis; TD, tuberculum dorsalis; TSD, tuberculum supracondylare dorsale; TSV, tuberculum supracondylare ventrale; VS, ventral sulcus. Scale bars 10mm.


Fig. 2. Eagle-sized fossil accipitrid material from South Australia: Cryptogyps lacertosus, Green Waterhole Cave, thoracic vertebra SAMA P24329 in A, caudal, B, lateral, and C, cranial view; Dynatoaetus pachyosteus, right quadrate in D, medial, E, lateral and F, ventral view; C. lacertosus, Green Waterhole Cave, os metatarsale I in G, plantar and H, dorsal view. Abbreviations: CC, condylus caudalis; CL, condylus lateralis; CM, condylus medialis; CO, capitulum oticum; CP, condylus pterygoideus; CQ, cotyla quadratojugalis; CS, capitulum squamosum; FvC, fovea costalis; FV, foramen vertebrae; I, indentation; LM, lateral margin; PAT, processus articularis tarsometatarsalis; PO, processus orbitalis; Pr, projection; PV, processus ventralis; SR, sulcus ridges; ZCa, zygapophysis caudalis. Scale bar 10mm.

 

[Fred Ruhe]

Dynatoaetus Mather, Lee, Camens and Worthy, 2023

Type species
Dynatoaetus gaffae Mather, Lee, Camens and Worthy, 2023.

Remarks
Referred to Dynatoaetus based on the following characters. Humerus: the fossa brachialis is notably deepened, the epicondylus ventralis is weakly projecting. Ulna: the tuberculum carpale has very little cranial projection. Femur: the muscle scar proximal to the fossa poplitea is circular in shape, the epicondylus lateralis is strongly projecting, the crista supracondylaris medialis is prominent, the sulcus between the condyles is very deep.

Dynatoaetus pachyosteus sp. nov.

Diagnosis
A large accipitrid of similar size to Aquila audax and Cryptogyps lacertosus, with short, stout wing bones and very large and robust leg bones that exhibits the following unique combination of characters. Quadrate with (1) the processus orbitalis having a deepened sulcus on its medial facies. (2) There is no foramen basiorbitale nor a foramen rostromediale. (3) Condylus pterygoideus is prominent medially, projecting more so than the condylus medialis. Humerus with (4) a deep m. scapulohumeralis cranialis dorsally adjacent to the fossa pneumotricipitalis, (5) tuberculum supracondylaris dorsalis not prominent dorsally and only slightly so cranially, and (6) a markedly sigmoid curvature to the shaft. Pelvis with (7) a large, deep anterior fossa renalis. Femur with (8) the ligamental attachment scar proximal to the fossa poplitea, circular in shape and positioned centrally in the shaft.

Etymology
Combination of Ancient Greek pᾰvῠ�1 (‘pachys’, masculine), meaning ‘thick’, ‘large’, or ‘stout’, and the Ancient Greek ὀrs�eo�(ost�eon, neutral), meaning ‘bone’. The name references the size and robustness of the bones attributed to the species.

Holotype
SAMA P41517 (¼FU 1141) left humerus missing only tuberculum ventrale.

Paratypes
SAMA P59030, complete right quadrate (62.750–64.750, R13.50–15.50, D/D −2.00to −2.50); SAMA P59029, complete left ulna (–70to −30, R5.50–7.50, D/D −1.720to −1.970); SAMA P41515, right carpometacarpus missing distal end and most of os metacarpale minus (570–60.50, R120–130, D/D −1.750to −2.750); SAMA P41516, partial pelvis preserving synsacrum and most of right lateral side (57.50–62.50, R130– 14.50, D/D −0.50to −1.00); SAMA P41513, complete right femur (56.50–58.50, R10–20, D/D −0.50to −1.00). Five specimens, MNI ¼1. All can be attributed to the upper part of Unit 7 as defined by Reed (2003, Fig. 6.3O). All differ from similar-sized A. audax and C. lacertosus, where comparable, and are substantially smaller than D. gaffae, which is known from the same deposit; therefore, all are referred to D. pachyosteus.

Type locality, unit and age
Excavation co-ordinates (decimal feet) 64.50–670, R90–100, D/ D −0.50to −1.00, Main Fossil Chamber, Victoria Fossil Cave, Naracoorte, South Australia. Early–Middle Pleistocene, between 300–150ka (Arnold et al. 2022).

Zoobank registration
Zoobank LSID of publication: urn:lsid:zoobank.orgub: 16EEAC4F-71AF-4D64-9128-175D5E815491; Zoobank LSID of new species: urn:lsid:zoobank.org:act:3A539E7E-FDC0-4B2B- A12A-3D51DA8D2537.

Remarks
Dynatoaetus pachyosteus can be distinguished from D. gaffae (state in brackets) in the following features. Humerus: the tuberculum supracondylare ventrale is rounded in ventral view (peaked) and extends to the insertion of the m. pronator profundus (ends proximal to the insertion). The dorsal margin of the fossa brachialis is broadly separated from the ventral shaft margin by a distance over a third of fossa width (narrow separation, less than a quarter of shaft width). The dorsal scar for the m. extensor carpi radialis is a broad circle that spans up to half the epicondylus ventralis length (spans a third of length). Ulna: the ulnae are very similar between species, with the major differing factor being their size. Carpometacarpus: the fovea carpalis caudalis is slightly deepened (shallow). The facies caudal to the processus pisiformes is flattened (prominent muscle scar present). The processus extensorius is slightly upturned towards the proximal tip (mostly horizontal). Pelvis: the VFC pelvis is markedly smaller in size than that of D. gaffae. Femur: in cranial view, the base of the facies articularis antitrochanterica forms a slightly cranially protruding ridge (flattened line). The m. obturatorius lateralis scar is directly adjacent to the m. ischiofemoralis extensorius scar (separated by gap). The impressio gastrocnemialis intermedia prominently protrudes caudally from the caudal surface (flat, does not protrude). The base of the epicondylus lateralis forms a distinct angle with the crista tibiofibularis (continuous with crista). The crista supracondylaris medialis is extremely prominent, as formed by the tuberculum muscularis gastrocnemialis medialis (slight prominence, mostly flattened). The base of the fossa poplitea is slightly pneumatic (not pneumatic).
Dynatoaetus pachyosteus can be distinguished from Cryptogyps lacertosus (lectotype or Green Waterhole specimen state is in brackets) by the following features. Humerus: the processus flexorius and condylus ventralis have roughly equal distal extent (processus flexorius much shorter); tuberculum supracondylare dorsale essentially lacking and not prominent of epicondylus dorsalis (large, prominent dorsally); interior margin of the tuberculum supracondylare ventrale is angled across the shaft (parallel to shaft) and facet for ligament insertion on it is broadly ovoid (more elongate); the dorsal sulcus of the m. humerotricipitalis is broad and takes up at least half the shaft width (dorsal sulcus narrow, half the width of the ventral part of the sulcus); fossa m. brachialis moderately deep (substantially deeper). Ulna: the cotyla ventralis is shallow in ventral view (deep, quite concave); the dorsal facies of the shaft is rounded (flattened); the tuberculum ligamenti collateralis ventralis extends distally alongside the impressio brachialis and has a slight but noticeable ventral prominence (positioned proximal to impressio brachialis and completely flat); the fossa on the caudal margin of the cotyla ventralis is positioned in line with the crista intercotylaris and is shallow (ventrally adjacent to crista and deep); the olecranon is less robust (more robust); a muscle insertion is present on the ventral facies distal to the incisura radialis (all insertions on cranial facies); the caudo-dorsal facies is rounded (facies greatly flattened compared to the rest of shaft); the tuberculum carpale has very little cranial projection (prominent cranial projection); the angle of the ventral condylus dorsalis margin cuts across the shaft (angle more closely aligned to the shaft); the distal margin of the condylus dorsalis is level to that of the condylus ventralis (extends distal to the condylus ventralis). Carpometacarpus: the ventral rim of the trochlea carpalis terminates distal to the processus pisiformis and level with the processus alularis (terminates far proximal to processus pisiformis).
Dynatoaetus pachyosteus can be distinguished from Hieraaetus moorei (whose state is in brackets) by the following features: the sizes of the limb bones are significantly smaller than those of H. moorei. Quadrate: there is no foramen basiorbitale (present), the processus orbitalis has a deep sulcus on the medial side (no sulcus), the processus orbitalis has a strongly proximo-medial angle (angled more medially); the condylus pterygoideus strongly projects medially, with almost equal medial extent to the medial condyle (moderate projection with roughly half the extent of medial condyle). Humerus: the proximal margin of the insertion for the m. pectoralis is equivalent to the distal margin of the crista bicipitalis (ends well distal of the crista bicipitalis); the distal end of the crista deltopectoralis is continuous with the shaft (at an angle with the shaft); the dorsal insertion of the sulcus lig. transversus is separated from the rest by a prominent ridge (continuous); the dorsal fossa m. humerotricipitalis is deep (shallow); the facies between the tuberculum supracondylare dorsale and the epicondylus dorsalis is weakly convex (prominently convex); the distance between the ventral margin of the fossa brachialis is narrow, between a quarter to a fifth of the shaft width (extremely narrow less than a fifth of shaft width), the interior margin of the tuberculum supracondylare ventrale is oriented at a high angle across the shaft (parallel to shaft). Ulna: the depressio radialis is distinctly deepened (shallow, indistinct). Carpometacarpus: the os metacarpale minus is arched (flattened), the processus extensorius is oriented at a 140�angle (90�angle). Pelvis: the section of facies directly proximal to the antitrochanter has a deepened fossa present (no fossa in H. moorei), the antitrochanter has greater lateral projection than the crista dorsolateralis (less lateral extent in H. moorei), the processus costales of the vertebra acetabularis merge to form a narrow bridge that connects to the lateral margins (broad bridge in H. moorei). Femur: the tuberculum muscularis gastrocnemialis medialis is prominent (flattened in H. moorei); the proximal margin of the fossa poplitea is distinct from the rest of the cranial facies (continuous, less distinct in H. moorei); the muscular attachment proximal to the fossa poplitea is circular in shape and positioned central in the shaft (elongate oval, slightly offset laterally in H. moorei).

Fred


Fig. 3. Fossil bones of species of Dynatoaetus, pelvis (A–D), femora (E–P). Dynatoaetus pachyosteus, pelvis SAMA P41516 in A, dorsal, B, ventral, C, right lateral and D, caudal view. Dynatoaetus gaffae right femur SAMA P41514 (E, G, I, K, M, O) compared to D. pachyosteus, SAMA P41513, Victoria Fossil Cave (SA) (F, H, J, L, N, P), in cranial (E, F), caudal (G, H), lateral (I, J), proximal cranial (K, L), distal caudal (M, N) views, and outlines of musculature scars on proximal lateral facies (O, P). Abbreviations: Ant, antitrochanter; AFR, anterior fossa renalis; CD, crista dorsolateralis; CSS, crista spinosa synsacri; CTF, crista trochanteris foramen; DIC, dorsal iliac crests; ECS, extremitas cranialis synsacra; EL, epicondylus lateralis; FLC, fovea lig. capitis; FT, fossa trochanteris; FP, fossa poplitea; IGL, impressio gastrocnemialis lateralis; IGM, impressio gastrocnemialis intermedia; ILCC, impressio lig. cruciati caudalis et cranialis; ILCL, impressio lig. collateralis lateralis; LIC, linea intermuscularis cranialis; PC, processus costales; TMGM, tuberculum muscularis gastrocnemialis medialis. Black scale bar 10mm, black and grey scale bar 50mm.

 

[Fred Ruhe]

Accipitridae indet.

Referred material
AM F129563, AM F129564, ungual phalanges; AM F152515, a partial carpometacarpus. WAM 15.9.622, a pelvis synsacrum.

Locality, unit and age
Wellington Caves, New South Wales, Australia: AM F129563, AM F129564, AM F152515, no locality or stratigraphy data recorded, Pleistocene unconstrained. Leaena’s Breath Cave, Western Australia, Australia: WAM 15.9.622, found on surface of cave floor, Pleistocene unconstrained.

Remarks
Multiple species of large accipitrids are known from Wellington Caves, including A. audax (distal ulna CCW ID 4879 [field number]), C. lacertosus (distal humeri AM F58092, tarsometatarsus AM F58093), and D. gaffae (distal tibiotarsus AM F106562). The ungual phalanges are from the Old Collections, making their precise site of origin unknown. The phalanges could be D. pachyosteus or D. gaffae based on their size. The carpometacarpus is from a sedimentary layer in Cathedral Cave (layer 13) that has a mean modelled age of 64ka (Fusco et al. 2023) and could be either A. audax, C. lacertosus or D. pachyosteus based on size. WAM 15.9.622 was labelled as A. audax but could also potentially belong to C. lacertosus, or D. pachyosteus.

Fred

 

[Fred Ruhe]

Aquila audax (Latham, 1801)

Referred material
SAM P41565, left coracoid; SAM P41518, right femur; SAMA P59836, tarsometatarsus.

Locality, unit and age
Excavation co-ordinates (decimal feet) 670–680, R3.50–16.50, D/D −1.00to −1.50(P59836); 650, R70, D/D 0.00/–0.50(P41518); excavation data unknown (P41565); Main Fossil Chamber, Victoria Fossil Cave, Naracoorte, South Australia. Early–Middle Pleistocene, 300–150ka (Arnold et al. 2022).

Remarks
This fossil material is identical to that of living A. audax, based on comparisons to FUR 125 and 085. This material demonstrates that the species coexisted with D. gaffae and D. pachyosteus in South Australia.

Body mass estimation
Using the mass algorithms of Field et al. (2013), Campbell & Marcus (1992), and Campbell & Tonni (1983), body mass was predicted for different fossil bones of Cryptogyps lacertosus, Dynatoaetus gaffae and D. pachyosteus (Table 3). The predicted body mass for D. pachyosteus varied considerably by element. The length of the humerus gave the very low value of 2.9kg (Table 3), within the size range of a male Aquila audax (see Marchant & Higgins 1993). This seems unlikely based on the other mass estimates and the overall robustness of the bones. Worthy & Holdaway (2002) commented on how humerus length consistently produced low mass predictions compared to that of living raptors. In contrast, the least shaft circumference (LSC) gave a predicted mass of 9kg, which would be more consistent with a particularly large, robust eagle. The LSC of the femur generated an even greater predicted mass of around 13kg (Table 3), but it has been noted that predictions derived from the femur of birds sometimes overestimate actual mass (Handley et al. 2016). The coracoid of C. lacertosus generated a predicted mass of 11–12kg based on the length of the humeral articular facet and shaft width, though total length gave the result of 3kg. Dynatoaetus gaffae had consistently high results, ranging from 12kg (tibiotarsus LSC, Table 3) to more than 19kg (femur LSC, Table 3), though this is partly because there were no complete humeri or coracoids to get total length measurements from.
The large discrepancies between the different mass estimates can be explained by the fact that the algorithms were created using data collected from a wide range of bird species. This is particularly evident in the length measurements, where shorter bone lengths would be generally associated with lower body mass, not taking into account relative stoutness expected to be greater in short-winged flapping taxa compared to gliding taxa. Most likely, the true mass ranges for the fossil species would fall somewhere between the proposed estimates. Based on similarly sized species, D. gaffae could have reached up to 12kg in mass, C. lacertosus would probably have a similar range to A. audax of 3–6kg, while D. pachyosteus would have been at least several kilograms lighter than D. gaffae.

Fred


Fig. 4. Strict consensus tree from parsimony analysis of molecular and morphological data for accipitrid raptors (and outgroups). The six most-parsimonious trees had tree length ¼1857, CI ¼0.2143, HI ¼0.7857, RI ¼0.5767. Bootstrap values are given at each node.


Fig. 5. Majority-rule consensus tree for Bayesian analysis of combined molecular and morphological data (ordered, unlinked branches) for accipitrid raptors (and outgroups). Posterior probabilities (expressed as percentages) shown at nodes. Fossil taxa are coloured red.