Falco bakalovi Boev, 1999

NW Bulgaria. The material was identified by comparisonwith the holotype in the reference avian skeleton collectionof the NMNHS, as well as the osteological collectionsof the Centre des Sciences de la Tèrre, UniversitéClaude Bernard – Lyon (UCBL) in 1994–1995 and theNatural History Museum, Tring, a part of the NaturalHistory Museum, London, former British Museum ofNatural History (BMNH) in 1999 and 2003. It is kept inthe Vertebrate Animal Department of the NMNHS.The taxonomy follows White et al. (1994). The osteologicalterminology is after Baumel and Witmer (1993)and Livezey and Zusi (2006). The chronostratigraphyfollows Mein (1990) and Guerin (1990).All measurements (Tables 1–16, Fig. 1) have beentaken using calipers to 0.05 mm accuracy, but read tothe 1 st digit after decimal point. Description of the measuringmanner of some bones in fossil and recent Falco:humerus dex. dist.: a – thickness of condylus dorsalis;b – thickness of condylus ventralis; c – total width of c.dorsalis and c. ventralis (Table 4); ulna sin. prox.: a – longitudinaldiameter of cotyla ventralis; b – transversal diameter(length) of cotyla dorsalis; c – maximum width ofFig. 1. Manner of measurings of the pelvis in Falconidae(Drawings Vera Hristova)14

proximal diaphysis; d – length of depressio m. brachialis;e – width of diaphysis at the middle of depressio m. brachialis(Table 5); femur sin. dist.: a – width of distal epiphysis;b – diameter of condylus lateralis; c – diameterof condylus medialis; d – diameter (thickness) in sulcusintercondylaris; e – cranio-caudal thickness of the diaphysisabove distal epiphysis (Table 10); tibiotarsus dex.dist.: a – width of distal epiphysis; b – diameter of thecondylus medialis; c – diameter of the condylus lateralis;d – thickness in the incissura intercondylaris; e – widthof diaphysis in the proximal end of sulcus supratendineus(Table 11). The manner of other measuring is given onFig. 1. All generic names of the binominals are given abbreviatedin the text and are in full in the Appendix 1.“Smaller”, “much smaller”, “larger” or “much larger”in the “Comparison and discussion” section mean thatthe fossil specimen differs considerably in size from thespecimens of the compared species, and thus their taxonomicidentity is excluded.Systematic PalaeontologyThe general morphology of all 26 finds indicates thatthey belong to the group of the small falcons (Falcosp. ex gr. tinnunculus). As F. bakalovi is the only knownrepresentative of that group in the Varshets locality, werefer all these finds to the same species.Order FALCONIFORMES (Sharpe, 1874)Family FALCONIDAE (Vigors, 1824)Subfamily Falconinae (Vigors, 1824)Genus Falco Linnaeus, 1758Falco bakalovi Boev, 1999Holotype: Postacetabular part of the left half of pelvis,NMNHS 1642. Collected on July 25 th , 1990 by Z. Boev.Paratypes: humerus dex. dist. NMNHS 135; ulna sin.prox. NMNHS 131; ulna dex. dist. NMNHS 14 964; femursin. dist. NMNHS 223; tbt dex. dist. NMNHS 136.Comparison: See Tables 1–16; Fig. 1 and “Descriptionand comparison” section.Measurements of the paratypes: Tables 1–16; Fig. 1.Neodiagnosis: A small-sized (between F. tinnunculus andF. subbuteo) fossil species of genus Falco, differing bythe sharp transition (turn) of crista iliaca dorsolateralisover the ala ischii and the rounded (oval), but not angularshape of the caudal edge of foramen ilioischiadicum.Distinguishing differences from: (A) the modern F. tinnunculus:(1) distal humerus: blunter (rounder) epicondylusventralis; (2) рroximal ulna: shallower fossa underc. dorsalis, and almost twice narrower depressio m. brachialis;(3) distal ulna: thicker cond. ventralis ulnae in caudalview; (4) distal femur: much higher crista tibiofibularis incaudal view; (5) distal tbt: much thicker wall of the medialtendineal fossa above c. medialis; from (B) the MioceneF. bul garicus: (1) proximal ulna, (2) distal humerus and(3) distal tibiotarsus much stouter and robust.Locality: A ponor in a rocky hill, 6 km NNE of the townof Varshets (43.13° N, 23.17° E). Unconsolidated, unstratifiedsediments accumulated as terra-rossa clay. Thefossil bones are broken, locally forming a bone breccia.Chronology: Villafranchian. The associated mam malfauna (Spassov 1997 a, b, 2000; Popov, 2001) gaveTable 1The measurements of coracoid sin. in some fossil and recent Falco (ref. to Fig. 1 A)Taxa a b c d eFossil – VarshetsFalco bakalovi NMNHS 304 2.4 2.8 2.1 10.2 4.6RecentFalco chicquera BMNH 1965.18.1 3.5 3.5 2.0 11.7 ca. 7.1Falco chicquera BMNH 1993.2.5 2.6 2.8 1.7 10.0 6.1Falco columbarius BMNH 1930.3.24.264 2.4 2.8 1.9 10.0 5.8Falco columbarius BMNH 1930.3.24.267 2.7 2.6 1.8 10.5 6.6Falco columbarius BMNH 1988.61.1 2.7 3.1 1.7 10.6 7.0Falco naumanni BMNH 1955.15.2 2.6 2.9 1.6 8.9 6.2Falco naumanni BMNH 1961.13.4 2.2 2.8 1.6 3.8 5.5Falco newtoni BMNH 1897.5.10.29 2.2 2.6 1.5 7.4 ca. 4.7Falco sparverius BMNH 1954.3.2 2.0 2.4 1.7 7.2 5.2Falco subbuteo BMNH 1985.76.1 2.8 3.2 2.3 11.1 7.3Falco subbuteo BMNH 1994.39.1 3.0 3.3 1.8 11.5 7.3Falco subbuteo UCBL 111/2 2.9 2.7 1.8 11.4 5.2Falco tinnunculus BMNH 1930.3.24.275 2.9 3.1 1.8 10.3 6.9Falco tinnunculus UCBL 119/2 2.6 2.4 1.6 9.2 4.6Falco tinnunculus UCBL 119/3 2.8 2.6 1.7 9.3 4.6Falco vespertinus BMNH 1855.4.4.9 2.3 2.9 2.0 9.4 6.0Falco vespertinus BMNH 1869.10.19.12 2.3 2.4 1.8 8.7 5.2Falco vespertinus BMNH 1952.3.122 2.5 3.2 1.8 9.7 6.315

←Fig. 2. Falco bakalovi Boev (Photographs: Assen Ignatov)a, b, coracoid sin. NMNHS 304c, coracoid sin. NMNHS 305d, e, clavicula sin. prox. NMNHS 306f, humerus dex. dist. NMNHS 14 952g, h, humerus dex. dist. NMNHS 134i, j, k, humerus dex. dist. NMNHS 135l, ulna sin. prox. NMNHS 132the site a MN17/MNQ17 zone attribution (Mein, 1990;Guerin, 1990). Spassov (2000, 2003) attributed the sitein the St. Vallier unit between the levels of the localitiesRoccaneyra and St. Vallier.Description and comparisonSkeletal elements of the fore limbsand the pectoral girdleCoracoid sin. NMNHS 304 (Figs 2 a, b, Table 1). Thespecimen belongs to a juvenile/subadult individual. Itdiffers from: F. chicquera: similar in size and generalmorphology, but differs by the thinner shaft of coracoid;F. columbarius: sharper pr. acrocoracoideus; F. naumanni:by the larger size, and the relatively narrowerf. a. humeralis; F. newtoni: the same way as F. sparverius;F. sparverius: by the larger size, and the thicker shaftin c. scapularis; F. subbuteo: morphologically similar,but smaller and differs by the narrower f. a. humeralis,and narrower pr. acrocoracoideus; F. tinnunculus:high similarity in size, general shape and proportions,but differs by the almost twice narrower f. a. humeralis;F. vespertinus: sharper pr. acrocoracoideus, narrowerf. a. humeralis.Coracoid sin. NMNHS 305 (Fig. 2 c, Table 2). Thespecimen lacks caudal part of the sternal end and allhumeral end. Its preserved part (mainly the bone shaft)completely fits to No 304 in both morphology and size.Clavicula sin. prox. NMNHS 306 (Figs 2 d, e, Table 3).The specimen preserves the distal (humeral) half of the boneand differs from: F. chicquera: by the less rounded pr.acromialis; F. columbarius: shallower relief of f. a. ac-Table 2The measurements of coracoid sin. in some fossil and recent Falco (ref. to Fig. 1 B)Taxa a b c d eFossil – VarshetsFalco bakalovi NMNHS 305 7.7 15.9 2.9 2.1 5.2RecentFalco chicquera BMNH 1965.18.1 – – 3.2 – –Falco chicquera BMNH 1993.2.5 ca. 9.2 ca. 18.9 2.9 – 6.1Falco columbarius 1930.3.24.267 9.6 20.2 2.8 2.3 5.3Falco columbarius BMNH 1930.3.24.264 8.2 17.8 2.7 2.3 5.5Falco columbarius BMNH 1988.61.1 8.7 20.0 3.1 2.3 6.3Falco naumanni BMNH 1955.15.2 6.9 14.8 2.9 2.2 5.4Falco naumanni BMNH 1961.13.4 6.3 14.0 2.8 2.0 5.3Falco newtoni BMNH 1897.5.10.29 7.5 13.7 2.7 2.2 5.0Falco sparverius BMNH 1954.3.2 8.1 15.4 2.3 1.9 4.8Falco subbuteo BMNH 1985.76.1 9.0 18.0 3.0 2.4 6.2Falco subbuteo BMNH 1994.39.1 8.5 18.1 3.2 2.5 6.5Falco subbuteo UCBL 111/2 10.2 17.6 3.1 2.4 6.6Falco tinnunculus BMNH 1930.3.24.275 9.3 17.9 3.3 2.4 5.7Falco tinnunculus UCBL 119/2 9.0 16.4 2.8 2.1 5.2Falco tinnunculus UCBL 119/3 8.2 16.0 3.4 2.2 5.2Falco vespertinus BMNH 1855.4.4.9 7.6 16.1 2.2 1.7 5.7Falco vespertinus BMNH 1869.10.19.12 8.7 16.4 2.5 2.3 5.1Falco vespertinus UCBL 117/1 10.0 18.9 3.1 2.0 5.817

Table 3The measurements of clavicula sin. prox. in some fossil and recent Falco (ref. to Fig. 1 C, D, E)Taxa a b c d eFossil – VarshetsFalco bakalovi NMNHS 306 1.8 3.4 1.1 6.1 5.3RecentFalco chicquera BMNH 1965.18.1 – 3.5 1.5 7.2 –Falco chicquera BMNH 1993.2.5 6.6 2.9 1.1 6.6 3.9Falco columbarius BMNH 1930.3.24.264 1.7 2.1 0.9 5.0 3.8Falco columbarius BMNH 1930.3.24.267 1.8 3.2 0.7 5.5 6.0Falco columbarius BMNH 1988.61.1 1.7 3.0 0.8 6.1 4.9Falco naumanni BMNH 1955.15.2 1.5 2.8 0.9 4.9 4.4Falco newtoni BMNH 1897.5.10.29 1.4 2.6 0.9 4.0 3.0Falco sparverius BMNH 1954.3.2 1.7 2.4 1.0 3.9 3.4Falco subbuteo BMNH 1994.39.1 1.9 3.8 1.3 6.5 4.2Falco subbuteo UCBL 111/3 1.8 3.4 1.0 6.8 5.5Falco subbuteo UCBL 111/4 1.5 2.8 1.1 6.0 5.3Falco tinnunculus BMNH 1930.3.24.275 1.5 2.8 1.8 4.7 5.2Falco tinnunculus BMNH 1930.3.24.278 1.2 2.8 1.7 5.2 4.4Falco tinnunculus UCBL 119/7 1.5 2.7 1.0 5.1 5.0Falco tinnunculus UCBL 119/8 1.2 2.6 0.9 5.1 4.1Falco vespertinus BMNH 1855.4.4.9 1.8 2.8 1.1 5.2 4.2Falco vespertinus BMNH 1869.10.19.12 1.8 2.8 0.9 4.3 3.6Falco vespertinus BMNH 1952.3.122 1.7 2.8 0.9 4.3 3.8Table 4The measurements of humerus dex. dist. in some fossil and recent FalcoTaxa a b cFossil – VarshetsFalco bakalovi NMNHS 134 4.7 2.2 ca. 7.4Falco bakalovi NMNHS 135 4.8 2.4 ca. 7.6Falco bakalovi NMNHS 14 952 5.8 ca. 2.8 ca. 8.5RecentFalco chicquera BMNH 1965.18.1 6.3 3.2 7.8Falco chicquera BMNH 1993.2.5 5.0 2.7 6.5Falco columbarius BMNH 1930.3.24.264 5.3 2.6 6.9Falco columbarius BMNH 1930.3.24.267 5.6 2.7 7.4Falco columbarius BMNH 1988.61.1 5.7 2.9 7.4Falco naumanni BMNH 1955.15.2 5.5 2.6 6.9Falco naumanni BMNH 1961.13.4 4.9 2.7 5.8Falco newtoni BMNH 1897.5.10.29 4.6 2.3 5.1Falco sparverius BMNH 1954.3.2 4.8 2.2 5.7Falco subbuteo BMNH 1974.16.1 6.3 3.0 7.9Falco subbuteo BMNH 1985.76.1 6.2 3.0 8.4Falco subbuteo BMNH 1994.39.1 6.5 3.0 8.5Falco tinnunculus BMNH 1930.3.24.275 4.2 2.9 7.8Falco tinnunculus BMNH 1930.3.24.276 6.1 2.9 8.2Falco tinnunculus BMNH 1930.3.24.278 5.3 2.7 6.8Falco vespertinus BMNH 1855.4.4.9 5.2 2.7 6.7Falco vespertinus BMNH 1869.10.19.12 5.1 2.7 6.7Falco vespertinus BMNH 1952.3.122 5.2 2.6 7.418

ocoracoidea, larger distance between the f. a. acrocoracoidea;F. naumanni: by the wider f. a. acrocoracoidea;F. newtoni: by the larger size, and the deeper relief of theacrocoracoidal articular end; F. sparverius: by the largersize; F. subbuteo: by the shorter f. a. acrocoracoidea;F. subbuteo: smaller, in cranio-lateral view the vow-likeprofile between the f. a. acrocoracoidaea is narrowerand round than open and elliptic; F. tinnunculus: widerf. a. acrocoracoidea and sharper pr. acrocoracoideus;F. vespertinus: larger size and the wider humeral partin lateral view.Humerus dex. dist. NMNHS 14 952 (Fig. 2 f, Table 4).The specimen preserves only fragment of dorsal (lateral)part of the distal epiphysis. It differs from: F. chicquera:by the deeper relief on the dorsal side of distal epiphysis.F. columbarius: less developed pr. supracondylaris dorsalis,smaller diameter of cond. dorsalis; F. naumanni:mainly by the larger size. F. newtoni: the same way asF. sparverius; F. sparveriusi: by the larger size. F. subbuteo:smaller, in caudal view cond. dorsalis more shortened;F. tinnunculus: similar, but slightly larger, differsby the wider facies a. acrocoracoidea, and narrower cond.ventralis humeralis; F. vespertinus: similar, but cond.dorsalis slightly bigger in caudal view.Humerus dex. dist. NMNHS 134 (Figs 2 g, h, Table 4).The specimen belongs to a juvenile/subadult individual. F.tinnunculus: dimensionally completely fits.Humerus dex. dist. NMNHS 135 (Figs 2 i, j, k,Table 4). F. columbarius: more straight distal diaphysis,shorter epicondylus dorsalis; F. subbuteo: smaller size;shallower sulcus m. humerotricipitis, shorter pr. flexoriusin medial view; F. tinnunculus: blunter (rounder)epicondylus ventralis; F. vespertinus: the same way asF. tinnunculus.Ulna sin. prox. NMNHS 131 (Table 5). The specimendiffers from: F. chicquera: by the more straight,instead slightly curved shaft of the proximal part of diaphysis;F. chicquera: by the relatively slightly narrowerc. dorsalis; F. columbarius: by the wider diaphysis, andthe wider depressio m. brachialis; F. naumanni: by thelarger size, and the less oval, instead angular, in dorsaledge, c. dorsalis; F. subbuteo: smaller, c. ventralis ismore angular, instead round; F. tinnunculus: similar,but differs by the thicker diaphysis, shallower fossaunder c. dorsalis, and almost twice narrower depressiom. brachialis; F. vespertinus: more robust, longer olecranon,c. dorsalis more angular than round.Ulna sin. prox. NMNHS 132 (Fig. 2 l, Table 5). Thespecimen differs the same way as No 131.Ulna dex. dist. NMNHS 294 (Fig. 3 a, Table 6).The specimen belongs to a juvenile/subadult individual,reached its definitive size. The dorsal part of c. dorsalisulnaris had been broken. Beside the incompletely developedarticular surfaces, the distal epiphysis bears thecharacteristic features of Falconiformes and Falconidae,especially the widely open depressio radialis, the wider(in comparison to Accipitridae) s. intercondylicus, andthe more protuberant in ventral direction tuber carpale.Metrically and morphologically completely fits to smallerPalearctic falcons of genus Falco. It differs from:Table 5The measurements of ulna sin. prox. in some fossil and recent FalcoTaxa a b c d eFossil – VarshetsFalco bakalovi NMNHS 131 4.4 4.0 8.3 13.5 4.7Falco bakalovi NMNHS 132 4.5 4.0 7.9 10.6 4.9RecentFalco chicquera BMNH 1965.18.1 5.1 4.8 8.9 11.2 5.1Falco chicquera BMNH 1993.2.5 4.5 3.8 7.8 ca. 9.4 4.1Falco columbarius BMNH 1930.3.24.264 4.0 4.2 7.4 ca. 10.2 ca. 4.2Falco columbarius BMNH 1930.3.24.267 4.3 3.4 8.0 9.5 4.3Falco columbarius BMNH 1988.61.1 4.5 3.9 8.1 9.7 4.4Falco naumanni BMNH 1955.15.2 4.2 3.7 7.7 12.3 4.1Falco naumanni BMNH 1961.13.4 3.9 3.5 6.9 10.5 3.9Falco newtoni BMNH 1897.5.10.29 3.7 3.0 6.2 7.6 3.6Falco sparverius BMNH 1954.3.2 3.6 2.8 6.5 8.2 4.1Falco subbuteo BMNH 1974.16.1 4.7 4.0 9.3 11.0 5.2Falco subbuteo BMNH 1985.76.1 4.4 4.3 8.5 ca. 10.9 4.9Falco subbuteo BMNH 1994.39.1 4.9 3.9 8.9 11.2 4.7Falco tinnunculus BMNH 1930.3.24.275 4.1 3.8 8.0 11.4 4.5Falco tinnunculus BMNH 1930.3.24.276 4.8 3.9 8.3 11.3 4.9Falco tinnunculus BMNH 1930.3.24.278 4.4 3.6 7.8 10.8 4.3Falco vespertinus BMNH 1855.4.4.9 4.8 3.8 7.8 11.7 4.0Falco vespertinus BMNH 1869.10.19.12 3.9 3.2 7.3 11.7 4.1Falco vespertinus BMNH 1952.3.122 4.2 3.3 7.4 9.0 4.619

←Fig. 3. Falco bakalovi Boev (Photographs: Assen Ignatov)a, ulna dex. dist. NMNHS 294b, ulna dex. dist. NMNHS 14 964c, ulna sin. dist. NMNHS 364d, e, carpometacarpus dex. prox. NMNHS 124f, g, h, carpometacarpus sin. prox. NMNHS 189i, carpometacarpus sin. dist. NMNHS 122j, k, l, femur sin. dist. NMNHS 223F. columbarius: larger and more robust, more angularc. ventralis and c. dorsalis; F. subbuteo: smaller size,shallower s. radialis; F. tinnunculus: shallower s. tendineus;F. vespertinus: lower cond. dorsalis.Ulna dex. dist. NMNHS 14 964 (Fig. 3 b, Table 6).The specimen differs from: F. chicquera: by the absenceof clear constriction between the diaphysis and cond.ventralis in lateral view; F. columbarius: slightly bigger,wider s. radialis, higher c. ventralis; F. naumanni: by thelarger size, and the shallower s. radialis; F. newtoni: bythe larger size, and by the straight, instead slightly curveddistal fourth of diaphysis in lateral view; F. sparverius:by the larger size; F. subbuteo: by the deeper s. radialis;F. tinnunculus: very similar, but slightly larger; thickercond. ventralis ulnae in caudal view; F. vespertinus:thicker diaphysis, deeper s. radialis.Ulna sin. dist. NMNHS 364 (Fig. 3 c, Table 6). Thespecimen differs the same way as No 294.Carpometacarpus dex. prox. NMNHS 124 (Figs 3 d, e,Table 7). The specimen belongs to a juvenile/subadult individual.It differs from: F. columbarius: of similar size;F. subbuteo: smaller, less steep caudal profile of tr. carpalis;F. tinnunculus: by the narrower f. a. radiocarpalis;F. vespertinus: more angular cranial edge of the dorsalcondyle of trochlea carpalis.Carpometacarpus sin. prox. NMNHS 189 (Figs 3 f,g, h, Table 8). The specimen differs from: F. chicquera:by the larger size and the slightly concaved caudal pro-Table 6The measurements of ulna dex. dist. in some fossil and recent Falco (ref. to Fig. 1 F)Taxa a b c dFossil – VarshetsFalco bakalovi NMNHS 294 4.5 6.3 4.1 3.8Falco bakalovi NMNHS 14 964 4.7 6.8 4.2 3.7RecentFalco chicquera BMNH 1965.18.1 – 7.0 4.9 4.4Falco chicquera BMNH 1993.2.5 4.2 6.0 3.5 3.3Falco columbarius BMNH 1930.3.24.264 4.1 6.2 3.8 3.4Falco columbarius BMNH 1930.3.24.267 4.5 6.7 3.5 3.5Falco columbarius BMNH 1988.61.1 4.6 6.6 3.5 3.6Falco naumanni BMNH 1955.15.2 4.5 6.0 4.0 3.4Falco naumanni BMNH 1961.13.4 4.1 5.9 3.4 3.1Falco newtoni BMNH 1897.5.10.29 3.6 5.1 3.1 2.9Falco sparverius BMNH 1954.3.2 3.6 5.4 3.4 3.0Falco subboteo UCBL 111/4 5.4 7.4 4.2 3.8Falco subbuteo UCBL 111/2 4.8 7.2 4.3 3.7Falco subbuteo UCBL 111/3 4.8 6.9 4.4 3.7Falco tinnunculus UCBL 119/1 4.6 7.1 4.6 3.8Falco tinnunculus UCBL 119/2 4.2 5.9 3.7 3.3Falco tinnunculus UCBL 119/3 4.4 6.2 4.0 3.4Falco tinnunculus UCBL 119/7 4.6 6.7 4.2 3.9Falco vespertinus BMNH 1855.4.4.9 4.2 6.3 4.2 3.8Falco vespertinus UCBL 117/1 4.4 6.1 3.8 3.4Falco vespertinus UCBL 117/2 4.2 5.7 3.6 3.021

Table 7The measurements of carpometacarpus dex. prox. in some fossil and recent Falco(ref. to Fig. 1 G)Taxa a b cFossil – VarshetsFalco bakalovi NMNHS 124 4.8 5.1 2.6RecentFalco chicquera BMNH 1965.18.1 5.2 5.9 3.1Falco chicquera BMNH 1993.2.5 3.7 5.3 2.8Falco columbarius BMNH 1930.3.24.264 4.5 5.4 2.7Falco columbarius BMNH 1930.3.24.267 5.2 6.8 2.7Falco columbarius BMNH 1988.61.1 4.4 5.7 2.9Falco naumanni BMNH 1955.15.2 4.5 4.8 2.6Falco naumanni BMNH 1961.13.4 4.3 5.0 2.4Falco newtoni BMNH 1897.5.10.29 4.0 5.1 2.6Falco sparverius BMNH 1954.3.2 3.8 4.5 2.5Falco subbuteo BMNH 1974.16.1 5.6 6.6 3.6Falco subbuteo BMNH 1985.76.1 5.0 6.5 4.3Falco subbuteo BMNH 1994.39.1 5.5 7.2 3.6Falco tinnunculus UCBL 119/2 4.5 5.6 2.7Falco tinnunculus UCBL 119/3 4.2 5.6 2.6Falco tinnunculus UCBL 119/4 4.4 5.7 2.7Falco vespertinus BMNH 1855.4.4.9 4.6 5.2 2.9Falco vespertinus BMNH 1869.10.19.12 4.3 5.3 2.8Falco vespertinus BMNH 1952.3.122 4.9 5.4 2.6Table 8The measurements of carpometacarpus sin. prox. in some fossil and recent Falco (ref. to Fig. 1 H)Taxa a b c d eFossil – VarshetsFalco bakalovi NMNHS 189 6.0 10.1 3.7 11.4 4.3RecentFalco chicquera BMNH 1965.18.1 6.5 – 3.3 12.0 –Falco chicquera BMNH 1993.2.5 5.5 7.2 3.1 10.2 3.9Falco columbarius BMNH 1930.3.24.264 5.5 8.8 2.0 9.8 3.5Falco columbarius BMNH 1930.3.24.267 6.8 9.3 2.6 11.8 3.7Falco columbarius BMNH 1988.61.1 6.1 9.2 3.0 11.7 3.8Falco naumanni BMNH 1955.15.2 5.2 8.8 3.8 10.4 3.6Falco naumanni BMNH 1961.13.4 5.2 8.4 2.7 10.4 3.5Falco newtoni BMNH 1897.5.10.29 5.1 6.3 2.7 ca. 8.6 3.2Falco sparverius BMNH 1954.3.2 4.8 6.3 2.6 8.8 3.3Falco subbuteo BMNH 1974.16.1 6.8 8.8 3.8 12.4 4.6Falco subbuteo BMNH 1985.76.1 6.3 10.7 3.6 12.0 4.1Falco subbuteo BMNH 1994.39.1 6.5 9.0 3.7 11.2 4.4Falco tinnunculus BMNH 1930.3.24.275 5.8 8.4 3.0 10.7 4.0Falco tinnunculus BMNH 1930.3.24.278 6.1 9.0 3.0 10.3 3.6Falco tinnunculus UCBL 119/7 5.5 9.4 3.2 10.2 3.8Falco vespertinus BMNH 1855.4.4.9 5.5 9.2 3.0 11.6 4.0Falco vespertinus BMNH 1869.10.19.12 5.2 7.2 3.0 10.8 3.4Falco vespertinus BMNH 1952.3.122 5.7 9.1 3.1 9.2 3.222

Table 9The measurements of carpometacarpus sin. dist. in some fossil and recent Falco (ref. to Fig. 1 I)Taxa a b c dFossil – VarshetsFalco bakalovi NMNHS 122 ca. 3.3 6.5 3.1 4.4RecentFalco chicquera BMNH 1965.18.1 3.0 6.8 3.1 4.6Falco chicquera BMNH 1993.2.5 3.0 6.3 2.2 3.7Falco columbarius BMNH 1930.3.24.264 3.9 6.0 2.7 3.7Falco columbarius BMNH 1930.3.24.267 4.2 6.2 2.4 3.8Falco columbarius BMNH 1988.61.1 4.1 5.6 2.5 4.2Falco naumanni BMNH 1955.15.2 3.7 6.2 2.5 4.0Falco naumanni BMNH 1961.13.4 3.2 5.4 2.3 3.6Falco newtoni BMNH 1897.5.10.29 2.7 5.0 2.2 3.3Falco sparverius BMNH 1954.3.2 3.3 4.8 2.2 3.0Falco subbuteo BMNH 1985.76.1 4.5 6.8 2.7 4.3Falco subbuteo BMNH 1994.39.1 4.6 6.8 2.8 4.4Falco subbuteo UCBL 111/3 3.8 7.0 3.2 4.0Falco tinnunculus UCBL 119/1 3.8 7.3 2.9 4.2Falco tinnunculus UCBL 119/2 3.7 6.7 2.8 4.0Falco tinnunculus UCBL 119/6 3.6 7.0 2.9 4.0Falco vespertinus BMNH 1855.4.4.9 4.4 5.9 2.5 3.9Falco vespertinus UCBL 117/2 3.5 6.1 2.6 3.6Falco vespertinus UCBL 117/4 3.8 6.4 2.6 3.7file of trochlea carpalis; F. columbarius: slightly larger insize, deeper s. between pr. extesorius and the lateral condyleof dorso-lateral view, longer pr. extensorius; F. naumanni:by the larger size and the bigger pr. pisiformis;F. new toni: the same way as F. sparverius; F. sparverius:by the larger size, and the much deeper constriction betweenpr. extensorius and the lateral condyle of the trochleacarpalis in lateral view; F. subbuteo: more proximalposition of the synostosis metacarpalis proximalis, morereversed (upright) inception of the os metacarpale minus;F. tinnunculus: by the slightly larger size, shorter incissuratendineus on the os metacarpalis majoris, and theshorter and rounder pr. pisiformis; F. vespertinus: largersize, and by the bigger pr. pisisformis.Carpometacarpus sin. dist. NMNHS 122 (Fig. 3 i,Table 9). The specimen differs from: F. columbarius:slightly bigger; F. subbuteo: smaller, by the round, insteadof pear-shaped protuberance of the middle partof f. a. digitalis major, by its stronger protruding, by itsvertical orientation towards the joint axis, by its moreventral position (reaching the edge), by the shallower s.tendineus in its distal end; F. tinnunculus: f. a. digiti minorisnarrower and all differences listen for F. subbuteo;F. vespertinus: bigger, thicker f. a. digiti majoris.Skeletal elements of the hind limbsand the pelvis girdleFemur sin. dist. NMNHS 223 (Figs 3 j, k, l, Table 10).The specimen differs from: F. chicquera: by the clearlywider cond. lateralis in ventral view; F. columbarius:wider impressio ansae m. iliofibularis, shorter crista supracondylarismedialis, wider cond. medialis in cranialview; F. naumanni: by the larger size, and the relativelylarger crista supracondylaris medialis; F. newtoni: by thelarger size; F. sparverius: by the larger size, and the moreasymmetrical s. patellaris in ventral view; F. subbuteo:smaller, more developed and sharper tuberculum musculigastrocnemialis lateralis; F. tinnunculus: much highercrista tibiofibularis in caudal view, by the wider cristasupracondylaris medialis; F. vespertinus: bigger in size,and the smaller tuberculum m. gastrocnemialis lateralis.Tbt dex. dist. NMNHS 136 (Fig. 4 a, Table 11). Thespecimen differs from: F. chicquera: the same way asF. subbuteo; F. columbarius: slightly larger general size,larger distal part of diaphysis, wider pons supratendineus;F. naumanni: the same way as F. vespertinus; F. newtoni:the same way as F. sparverius; F. subbuteo: morerobust and larger distal part of diaphysis, deeper depressioepicondylaris lateralis; F. sparverius and F. newtoni:by the larger size, and the relatively wider distal part ofdiaphysis; F. tinnunculus: by the much thicker wall of themedial tendineal fossa above c. medialis, by the thinnercond. medialis in ventral view and by the wider (more robust)distal third of diaphysis; F. vespertinus: larger size,and the relatively wider distal part of diaphysis.Tbt dex. dist. NMNHS 145 (Fig. 4 b, Table 11). Thespecimen differs the same way as No 136.Tmt dex. prox. NMNHS 123 (Figs 4 c, d, Table 13).The specimen differs from: F. columbarius: bigger in23

Table 10The measurements of femur sin. dist. in some fossil and recent FalcoTaxa a b c d eFossil – VarshetsFalco bakalovi NMNHS 223 7.6 6.2 6.2 4.5 4.7RecentFalco chicquera BMNH 1965.18.1 ca. 7.3 6.9 7.5 – 5.6Falco chicquera BMNH 1993.2.5 7.4 6.9 6.5 4.4 4.6Falco columbarius BMNH 1930.3.24.264 7.0 6.2 6.0 4.4 4.0Falco columbarius BMNH 1930.3.24.267 7.5 6.5 6.3 4.3 4.4Falco columbarius BMNH 1988.61.1 7.9 6.9 6.8 4.4 4.3Falco naumanni BMNH 1955.15.2 6.6 5.8 5.3 4.0 3.8Falco naumanni BMNH 1961.13.4 6.1 5.8 5.2 4.0 3.5Falco newtoni BMNH 1897.5.10.29 6.4 5.0 5.0 ca. 2.6 3.7Falco sparverius BMNH 1954.3.2 6.3 5.7 5.5 3.7 4.4Falco subbuteo BMNH 1974.16.1 8.3 7.4 7.0 5.0 4.8Falco subbuteo BMNH 1985.76.1 7.7 6.6 6.6 4.1 4.0Falco subbuteo BMNH 1994.39.1 8.5 7.2 6.8 4.6 4.7Falco tinnunculus BMNH 1930.3.24.275 8.2 7.1 6.2 5.6 4.5Falco tinnunculus BMNH 1930.3.24.276 8.2 7.2 6.5 4.6 5.0Falco tinnunculus BMNH 1930.3.24.278 7.7 6.8 6.0 4.1 4.0Falco vespertinus BMNH 1855.4.4.9 6.4 5.9 5.8 4.6 4.2Falco vespertinus BMNH 1869.10.19.12 6.2 5.5 5.4 4.5 4.9Falco vespertinus BMNH 1952.3.122 6.8 5.9 6.0 4.2 4.2size, less prominent lateral edge of c. lateralis; F. subbuteo:smaller size, probably lower crista medialis hypotarsi(partly broken); F. tinnunculus: by the shallowerc. medialis in cranial view; F. vespertinus: bigger in size.Tmt dex. prox. NMNHS 143 (Fig. 4 e, Table 12).The specimen differs from: F. columbarius: more angularinstead round, c. medialis; F. subbuteo: higher faciessubcutanea medialis and facies subcutanea lateralis; F.tinnunculus: lower eminentia intercondylaris; F. columbarius:bigger, wider proximal third of diaphysis. F. vespertinus:bigger in size.Tmt sin. NMNHS 144 (Fig. 4 f; Table 12). The specimenbelongs to a juvenile individual of almost definitesize. The specimen differs the same way as No 123.Phalanx 1 dig. I pedis dex. NMNHS 319 (Fig. 4 g,Table 14). The specimen differs from: F. columbarius:thicker phalangeal body; F. subbuteo: smaller, slightlymore asymmetrical trochlea a. in cranial view; F.tinnunculus: by the smaller dimensions, and particularlylesser diameter of the condyles of the trochlea;F. vespertinus: bigger, both condyles more parallel indorsal view.Fig. 4. Falco bakalovi Boev (Photographs: Assen Ignatov)a, tbt dex. dist. NMNHS 136b, tbt dex. dist. NMNHS 145c, d, tmt dex. prox. NMNHS 123e, tmt dex. prox. NMNHS 143f, tmt sin. NMNHS 144g, phalanx 1 dig. I pedis dex. NMNHS 319h, phalanx 1 dig. I pedis dex. NMNHS 320i, phalanx 1 dig. I pedis dex. NMNHS 321j, phalanx 2 dig. II pedis dex. NMNHS 317k, phalanx 2 dig. II pedis sin. NMNHS 318l, phalanx dist. dig. 1 pedis dex. NMNHS 181 – lateral view (above) and caudal view (bellow)←24

Table 11The measurements of tibiotarsus dex. dist. in some fossil and recent FalcoTaxa a b c d eFossil – VarshetsFalco bakalovi NMNHS 136 6.8 5.5 ca. 5.1 4.3 6.0Falco bakalovi NMNHS 145 ca. 7.2 5.5 – 4.0 5.0RecentFalco chicquera BMNH 1965.18.1 7.8 6.0 6.3 4.6 5.4Falco chicquera BMNH 1993.2.5 6.7 5.0 5.4 3.9 4.3Falco columbarius BMNH 1930.3.24.264 6.0 5.0 4.7 3.6 4.0Falco columbarius BMNH 1930.3.24.267 6.7 5.3 5.0 3.5 4.3Falco columbarius BMNH 1988.61.1 6.9 5.4 5.0 3.8 4.4Falco naumanni BMNH 1955.15.2 6.0 4.6 4.8 3.2 4.0Falco naumanni BMNH 1961.13.4 5.6 4.7 4.6 3.3 3.5Falco newtoni BMNH 1897.5.10.29 5.6 4.5 4.5 3.1 4.3Falco sparverius BMNH 1954.3.2 5.6 4.5 4.4 3.5 4.0Falco subbuteo BMNH 1974.16.1 7.1 5.3 5.8 3.7 4.4Falco subbuteo BMNH 1985.76.1 6.7 5.1 5.2 3.3 4.1Falco subbuteo BMNH 1994.39.1 7.2 5.6 5.9 4.2 4.3Falco tinnunculus BMNH 1930.3.24.275 7.1 5.6 5.7 4.4 4.8Falco tinnunculus BMNH 1930.3.24.276 6.8 5.7 5.6 4.1 4.6Falco tinnunculus BMNH 1930.3.24.278 6.6 5.4 5.3 3.7 4.2Falco vespertinus BMNH 1855.4.4.9 5.7 4.6 4.7 3.4 4.1Falco vespertinus BMNH 1869.10.19.12 5.2 4.7 4.5 3.3 3.5Falco vespertinus BMNH 1952.3.122 6.2 4.9 4.6 3.6 4.4Table 12The measurements of tarsometatarsus sin. in some fossil and recent Falco (ref. to Fig. 1 J, K)Taxa a b c d eFossil – VarshetsFalco bakalovi NMNHS 143 7.1 – – 2.9 –Falco bakalovi NMNHS 144 7.6 39.5 ca. 2.2 2.8 3.5RecentFalco columbarius NMNHS 1/1997 6.9 35.5 2.5 3.3 4.6Falco columbarius NMNHS 2/2002 6.5 36.3 2.2 2.8 4.3Falco subbuteo NMNHS 1/1989 8.4 35.7 3.4 3.4 5.1Falco subbuteo NMNHS 3/1993 6.9 35.4 3.2 3.1 4.6Falco tinnunculus UCBL 119/7 7.4 40.7 2.6 3.2 4.3Falco tinnunculus NMNHS 10/1991 7.4 41.4 2.7 3.0 4.4Falco vespertinus NMNHS 1/1991 6.2 29.3 2.3 2.7 3.6Phalanx 1 dig. I pedis dex. NMNHS 320 (Fig. 4 h,Table 14). The specimen differs the same way as No 319.Phalanx 1 dig. I pedis dex. NMNHS 321 (Fig. 4 i,Table 14). The specimen belongs to a juvenile/subadultindividual of almost definite size. It differsfrom: F. columbarius: more concave ventral side inthe proximal end; F. subbuteo: smaller; F. tinnunculus:by the smaller dimensions, and by the higher“parallelity” of the surfaces of both condyles of thetrochlea; F. vespertinus: biger, both condyles moreparallel in dorsal view.Phalanx 2 dig. II pedis dex. NMNHS 317 (Fig. 4 j,Table 15). The specimen differs from: F. columbarius:bigger and more robust; F. subbuteo: smaller, by the widerf. a. (measurement “c”); F. tinnunculus: by the smallerdiameter of the phalangeal trochlea, narrower trochlea26

Table 13The measurements of tarsometatarsus dex. prox. in some fossil and recent Falco (ref. to Fig. 1 L)Taxa a b c d eFossil – VarshetsFalco bakalovi NMNHS 123 3.7 3.1 4.4 7.7 7.2RecentFalco chicquera BMNH 1965.18.1 4.2 3.6 5.4 8.9 7.2Falco chicquera BMNH 1993.2.5 3.3 3.2 4.7 7.8 7.0Falco columbarius BMNH 1930.3.24.264 2.9 2.8 4.0 6.5 6.4Falco columbarius BMNH 1930.3.24.267 3.9 2.9 4.5 7.6 7.0Falco columbarius BMNH 1988.61.1 3.4 3.1 4.4 7.5 6.9Falco naumanni BMNH 1955.15.2 3.0 2.7 3.8 6.5 6.2Falco naumanni BMNH 1961.13.4 3.1 2.7 3.7 6.3 5.7Falco newtoni BMNH 1897.5.10.29 3.0 2.6 3.7 5.2 5.8Falco sparverius BMNH 1954.3.2 3.1 2.7 3.6 6.2 5.7Falco subbuteo BMNH 1974.16.1 3.6 3.2 4.8 7.9 7.4Falco subbuteo BMNH 1985.76.1 3.6 3.4 4.8 7.6 7.0Falco subbuteo BMNH 1994.39.1 3.6 3.4 5.2 8.3 7.2Falco tinnunculus BMNH 1930.3.24.275 3.7 3.3 4.5 7.7 7.0Falco tinnunculus BMNH 1930.3.24.278 3.6 2.8 4.5 7.3 6.9Falco tinnunculus UCBL 119/7 3.4 2.8 3.8 7.7 7.0Falco vespertinus BMNH 1855.4.4.9 3.1 3.0 3.7 6.5 6.2Falco vespertinus BMNH 1869.10.19.12 2.8 2.7 3.6 6.0 5.4Falco vespertinus BMNH 1952.3.122 3.0 2.6 3.9 6.9 6.7Table 14The measurements of phalanx 1 dig. I pedis in some fossil and recent Falco (ref. to Fig. 1 M)Taxa a b c d e fFossil – VarshetsFalco bakalovi NMNHS 319 2.4 2.2 3.2 2.2 9.9 1.4Falco bakalovi NMNHS 320 2.6 2.6 3.3 2.3 10.3 1.3Falco bakalovi NMNHS 321 2.2 2.0 3.3 2.2 10.4 1.3RecentFalco columbarius NMNHS 2/2002 2.2 2.4 3.3 2.2 9.7 1.2Falco subbuteo NMNHS 1/1989 2.6 2.5 4.1 2.9 12.6 1.6Falco subbuteo NMNHS 3/1993 2.2 2.0 3.2 2.2 10.3 1.2Falco tinnunculus NMNHS 10/1991 2.6 2.3 3.8 2.6 11.0 1.4Falco tinnunculus UCBL 119/1 2.5 2.4 3.9 2.5 11.4 1.5Falco tinnunculus UCBL 119/2 2.4 2.2 3.6 2.5 10.3 1.4Falco tinnunculus UCBL 119/3 2.2 2.1 3.3 2.3 9.8 1.3Falco tinnunculus UCBL 119/7 2.4 2.2 3.7 2.3 10.7 1.4Falco vespertinus NMNHS 1/1991 2.0 2.0 3.0 2.0 8.5 1.1(measurement “a”), possibly indication of more primitiveraptority, i. e. narrower and less strong claws; F. vespertinus:bigger and more robust.Phalanx 2 dig. II pedis sin. NMNHS 318 (Fig. 4 k,Table 15). The specimen belongs to a juvenile/subadultindividual of almost definite size. The specimen differsfrom: F. columbarius: narrower distal end; F. subbuteo:by the wider f. a. (measurement “c”); F. subbuteo: smaller;F. tinnunculus: The same way as No 317; F. vespertinus:bigger and more robust.Phalanx dist. dig. 1 pedis dex. NMNHS 181 (Fig.4 l,Table 16). The specimen differs from: F. columbarius:more robust; F. subbuteo: wider articular surfaces (measurement“d”); F. vespertinus: bigger in size and widerf. a.; F. vespertinus: bigger; Falco tinnunculus: by theshorter base of the attachment of the muscle.27

Table 15The measurements of phalanx 2 dig. II pedis in some fossil and recent Falco (ref. to Fig. 1 M)Taxa a b c d e fFossil – VarshetsFalco bakalovi NMNHS 317 1.9 1.8 2.6 2.2 9.7 1.4Falco bakalovi NMNHS 318 1.9 1.9 2.6 2.2 9.8 1.3RecentFalco columbarius NMNHS 2/2002 2.0 1.9 2.5 2.5 9.3 1.1Falco subbuteo NMNHS 1/1989 2.5 2.6 3.1 2.9 12.5 1.6Falco subbuteo NMNHS 3/1993 1.8 1.8 2.0 1.9 9.8 1.0Falco subbuteo UCBL 111/1 1.6 1.7 1.9 1.8 9.0 1.2Falco tinnunculus NMNHS 10/1991 2.1 2.0 2.4 2.4 9.8 1.3Falco tinnunculus UCBL 119/2 1.9 1.9 2.2 2.2 9.1 1.2Falco tinnunculus UCBL 119/3 2.0 2.0 2.5 2.4 9.7 1.3Falco tinnunculus UCBL 119/7 2.1 2.1 2.4 2.3 9.9 1.2Falco vespertinus NMNHS 1/1991 1.7 1.8 2.2 2.0 8.7 1.1Table 16The measurements of phalanx dist. dig.I pedis in some fossil and recent Falco (ref. to Fig. 1 N)Taxa a b c dFossil – VarshetsFalco bakalovi NMNHS 181 3.2 2.8 ca. 10.2 2.6RecentFalco columbarius NMNHS 2/2002 2.8 3.1 9.5 2.4Falco subbuteo NMNHS 1/1989 3.2 3.2 10.1 2.7Falco subbuteo NMNHS 3/1993 3.4 4.7 9.5 2.1Falco subbuteo UCBL 111/1 3.0 2.7 9.1 2.0Falco tinnunculus NMNHS 10/1991 3.8 2.9 10.5 2.6Falco tinnunculus UCBL 119/1 3.2 3.0 10.1 2.6Falco tinnunculus UCBL 119/2 3.1 2.7 10.2 2.4Falco tinnunculus UCBL 119/3 3.0 2.9 9.5 2.4Falco tinnunculus UCBL 119/7 3.5 2.9 10.2 2.8Falco vespertinus NMNHS 1/1991 4.0 2.8 8.0 1.8DISCUSSIONThe comparative analysis of the examined finds unequivocallyshows that they could only be referred tothe so-called “tinnunculus” group (Falco sp. ex gr. tinnunculus)of the smaller falcons in the genus Falco, wellseparated from the “cherrug” group of the larger falcons.Some finds, however, because of the worse degree oftheir preservation, or being specimens of immature individuals,could not be accepted as reliable proofs for theformer existing of a concrete definite species of Falcosp. ex gr. tinnunculus. Having in mind the common collectingof all material (common sample and horizon), andtheir dimensional characteristics, we refer all finds to asingle species. Its skeletal elements clearly differ fromall compared species of the recent fauna. They couldnot be referred also to the hitherto known fossil taxa ofgenus Falco. Considerations for that have been given inother paper (Boev, 1999a), describing the fossil speciesFalco bakalovi. The abundant excavated avian material(1589 finds, Boev, 2002; over 1700 finds, Boev, inpubl.data) collected so far, and its examination shows that notaxa are represented by now by a single find, and mostof them are represented by several (even several dozensof bones).The smallest Old World falcons (Microhierax Sharpe,1874 and Polihierax Kaup, 1847) are excluded from ourcomparison, because of their evident strong metrical differences.Their skeletal elements are more than twicesmaller compared to specimens of these genera.The sexual dimorphism in size should also be takeninto account. Hill (1944) examining Falconiformes ingeneral, stated that falcons of genus Falco constitute agroup of species demonstrating the most expressed sexualdimorphism (concerning length of the wing, tail, tarsus,and bill), reaching up to 37.8 % (male to female meas-28

urements). The only feature (tarsus length) where thebone structure determines much the size varies between2.0 and 20.5 %. On the other hand, Cramp and Simmons(1980) noted that in F. t. tinnunculus, for example, the“sex differences [are] significant for adult and juvenile,except for tarsus”. According to them these differencesin the wing length reach 6.30 to 8.48 %. Obviously theskeletal elements differ less.Two measurements of the proximal ulna show thatthe length of depressio m. brachialis in F. bulgaricusis 12.3 mm, while in F. bakalovi it is 7.9 to 8.3. On theother hand, the longitudinal diameter of cotyla ventralisin F. bulgaricus is ca. 4.9 mm while in F. bakalovi it is4.4 to 4.5 mm (Boev, 2011; Table 4). The general appearanceof the proximal ulna, distal humerus and distaltibiotarsus of F. bakalovi considerably differs fromF. bulgaricus. All these skeletal elements are muchstouter and robust.The morphology and size of F. bakalovi show thatit was a close late Pliocene relative to recent F. tinnunculus,having similar ecological features and biology.Until now it is the most abundant raptorial bird, foundin the Varshets locality and in Bulgaria at all (26 finds;4 individuals).AcknowledgmentsThe Foundation Scientifique de Lyon et du Sud-Est(Lyon), the Short-term Visits Program of the RoyalSociety (London), the National Science Fund, Sofia, grantNo B-202/1992), and the National Museum of NaturalHistory (Sofia) have supported the study. The author isvery grateful to Dr. Cécile Mourer-Chauviré (UCBL),Dr. Robert Prys-Jones and Dr. Joanne Cooper (BMNH)for their hospitality and help during the research visits attheir institutions. Special thanks to Dr. Nikolay Spassov(NMNHS) and an anonymous reviewer who improvedthe former version of the manuscript.APPENDIX 1Examined specimens belongingto recent species of FalconiformesAccipiter nisus (Linnaeus, 1758); UCBL 96/6; UCBL96/10;Falco chicquera Daudin, 1800: BMNH 1965.18.1,BMNH 1993.2.5;Falco columbarius Linnaeus, 1758: BMNH 1930.3.24.264, 1930.3.24.267, BMNH 1988.61.1;Falco naumanni Fleischer, 1818: BMNH 1955.15.2,BMNH 1961.13.4;Falco newtoni Gurney, 1863: BMNH 1897.5.10.29;Falco sparverius Linnaeus, 1758: BMNH 1954.3.2;Falco subboteo Linnaeus, 1758: BMNH 1974.16.1, BMNH1994.39.1, UCBL 111/1, UCBL 111/2, UCBL 111/3,UCBL 111/4;Falco tinnunculus Linnaeus, 1758: BMNH 1930.3.24.275,BMNH 1930.3.24.276, BMNH 1930.3.24.278, UCBL119/1, UCBL 119/2, UCBL 119/3, UCBL 119/4, UCBL119/6, UCBL 119/7, UCBL 119/8;Falco vespertinus Linnaeus, 1766: BMNH 1855.4.4.9,BMNH 1869.10.19.12, BMNH 1952.3.122, UCBL117/1, UCBL 117/2, UCBL 117/4;Microhierax caerulescens (Linnaeus, 1758): BMNH2002.41.2;Polihierax semitorqutus (Smith, 1846): BMNH 2002.41.1.ReferencesBaumel, J. J., Witmer, L. M. 1993. 4. Osteologia. In: Baumel,J., King, A., Breazile, J., Evans, H., Van den Berge, J.,(Eds.). Handbook of Avian Anatomy, Nomina AnatomicaAvium 23, 45–132. Nutall Ornithological Club.Boev, Z. 1999a. Falco bakalovi sp. n. – a Late Pliocene falcon(Falconidae, Aves) from Varshets (W Bulgaria). GeologicaBalcanica 29(1–2), 131–135.Boev, Z. 1999b. Neogenski i kvaternerni ptitsi (Aves) otBalgariya. [Neogene and Quaternary birds (Aves) fromBulgaria]. DSci. Thesis, National Museum of NaturalHistory, Bulgarian Academy of Sciences, Sofia, 243 pp.supplements (in Bulgarian, unpublished).Boev, Z. 2002. Neogene avifauna of Bulgaria. In: Zhou, Z.,Zhang, F. (Eds.) Proceedings of the 5th Symposium ofthe Society of Avian Paleontology and Evolution, Beijing,29–40.Boev, Z. 2011. Falco bulgaricus sp. n. (Aves, Falconiformes)from the Middle Miocene of Hadzhidimovo (SW Bulgaria).Acta zoologica bulgarica 63(1), 17–35.Cramp, S., K., Simmons, E. L. (Eds.). 1980. Handbook of theBirds of Europe the Middle East and North Africa. TheBirds of Western Palearctic, Vol. II. Hawks to Bustards.Oxford University Press, 695 pp.Guerin, C. 1990. Biozones or Mammal Units? Methods andlimits in Biochronology. In: Linday, E.H., Fahlbusch, V.,Mein, P. (Eds.). European Neogene mammal Chronology.Plenum Press, New York, 116–130.Hill, N. P. 1944. Sexual dimorphism in the Falconiformes. TheAuk, 61, 228–234.Livezey, B. C., Zusi, R. L. 2006. Higher-order phylogeny ofmodern birds (Theropoda, Aves: Neornithes) based oncomparative anatomy: I. Methods and Characters. Bulletinof Carnegie Museum of Natural History, Pittsburgh, 37,502–544.Mein, P. 1990. Updating of MN zones. In: Lindsay, E.H.,Fahlbusch, V., Mein, P. (Eds.) European Neogene mammalchronology. Plenum Press, New York, 73-90.Mlíkovský, J., 2002. Cenozoic Birds of the World. Part 1,Europe. Praha, Ninox Press. 406 pp.Popov, V. 2001. Late Pliocene voles (Mammalia, Arvicolidae)from Varshets (North Bulgaria). Acta zoologica cracoviensia44(2), 143–172.29

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