Note: A star "*" indicates additive or ordered characters. Some references for cranial and dental characters include "ch. # XX" to indicate the character number used by the original authors to refer to the same or similar feature.
(1) Atlantal foramen: 0 = absent; 1 = present. In Monodelphis domestica (SZ 6984, A. van Nievelt coll. 98011), Dasyuroides byrnei (SZ 6576), and Dromiciops gliroides (FMNH-129804) we found asymmetry in presence/absence, i.e., present on one side, absent in the other. These taxa were coded as polymorphic.
(2) Subdivision of atlantal foramen: 0 = absent; 1 = present.
(3) Atlas transverse foramen: 0 = absent; 1 = present. Specimens of Dasyuroides byrnei (SZ 6576) and Trichosurus vulpecula (SZ 6583) are asymmetric for this character.
(4) Atlas, posterior extent of transverse process: 0 = absent; 1 = present. We coded this character as "present" when the transverse processes extend caudally beyond the caudal facets for the axis.
(5) Atlas, cranial facets shape* (Fig. 9): 0 = only concave; 1 = dorsal edge curved; 2 = dorsal edge envelops the occipital condyle medially. We coded 0 when the surface is more or less equally concave along its entirety (same, even curvature), "1" when the dorsal end of the facet is more curved (concave) than the rest of the facet, covering the condyles dorsally, and "2" when the dorsal end of the facet curves even further, enveloping the condyles reaching their medial side. To further clarify, the dorsal end of these facets coded "2" faces almost laterally or laterally.
(6) Atlas, transverse process ventral to atlantal foramen groove: 0 = absent; 1 = present. We coded "1" those taxa where the transverse process extends anteriorly reaching the ventral area of the atlantal foramen. We coded "0" those taxa where the transverse process does not reach so far anteriorly.
(7) Atlas ventral arches (Fig. 9 and 10): 0 = open; 1 = complete. We mean by "complete" cases in which there was no space between the two arches ventrally; in cases where it is complete, presence or absence of an intercentrum is not considered here.
(8) Atlas intercentrum*: 0 = absent; 1 = present with no fusion; 2 = present, fused. If they there are no sutures visible on the ventral arch and there is no information from histological sections as to the presence of an intercentrum or not, the character is left blank.
(9) Axis transverse foramen: 0 = open; 1 = enclosed. In Macropus rufus (SZ 307, 3636) there is a partial "enclosure" (i.e., almost a foramen), we are not sure whether it has facets that articulate with unfused ribs that were lost during maceration.
(10) Axis posterior spinous process extension: 0 = absent; 1 = present. We coded 1 when the neural spine extends posteriorly beyond the vertebral arches.
(11) Axis extra pair of transverse processes on the ventral surface of the body: 0 = absent; 1 = present.
(12) Axis anterior facets (prezygapophyses) and dens connection*: 0 = not linked; 1 = linked; 2 = facets extend ventral to the dens. "Linked" refers to the condition in which there is no clear border between the articular facets and the dens, but rather a continuous surface.
(13) Suture between rib and axis is visible (Fig. 11): 0 = no; 1 = suture visible.
(14) Axis-C3-C4 fusion*: 0 = no fusion; 1 = axis and C3 fused; 2 = axis-C3-C4 fused.
(15) C3-C4 ventral sagittal process: 0 = absent; 1 = present.
(16) C5 transverse process displays two heads (Fig. 12): 0 = absent; 1 = present.
(17) C5 transverse process heads overlap transversally (Fig. 12): 0 = absent; 1 = present.
(18) C5 and T1 body length: 0 = subequal or C5 longer than T1; 1 = C5 shorter than T1. The anteroposterior length of vertebrae C5 and T1 was measured in ventral view and the ratio C5/T1 was calculated for each taxon. Taxa with values equal to or larger than 0.9 were coded as “0” and those equal or smaller than 0.8 were coded as “1”.
(19) C6 transverse process posterior extension (Fig. 12): 0 = absent; 1 = present.
We coded "present" when the transverse process extends posteriorly beyond the articulation between the bodies of C6 and C7.
(20) C6 spinous process* (Fig. 12): 0 = absent; 1 = protuberance; 2 = lamina.
(21) C7 transverse foramen*: 0 = absent; 1 = incipient; 2 = present.
(22) Articulation among cervical vertebrae: 0 = only bodies articulate; 1 = prezygapophyses and postzygapophyses in addition to bodies articulate.
(23) Articulation between C4-C5 bodies type (Fig. 2): 0 = flat; 1 = saddle. We code "saddle" when the anterior side of each body embraces the posterior side of the previous (anterior, cranial) body.
(24) T1 transverse process: 0 = absent; 1 = present.
(25) T1 transverse process level: 0 = level with prezygapophysis; 1 = lower than prezygapophysis.
(26) First thoracic vertebra with a (relative to other vertebrae) tall spinous process: 0 = T1; 1 = T2; 2 = T3.
(27) First thoracic vertebrae with prezygapophysis facing laterally: 0 = T1; 1 = T2; 2 = T3.
(28) Thoracic vertebrae, intervertebral foramen enclosed: 0 = absent; 1 = present. The intervertebral foramen can be enclosed on the caudal area of the vertebral arch in thoracic vertebrae.
(29) Last lumbar vertebra, foramen on dorsal arch: 0 = absent; 1 = present. Though we coded this character on the last lumbar only, this foramen is present in all lumbar and most thoracic vertebrae and both sacrals in some cases, e. g., Macropus rufus (SZ 307, 3636). This canal opens also in the vertebral canal in all the vertebrae just mentioned for M. rufus (i.e., most thoracic plus lumbar and both sacrals), whereas in Dorcopsis veterum (SZ 4225) only the last lumbar shows an opening within the vertebral canal. This opening whithin the vertebral canal can be seen in some cases in caudal view of the corresponding vertebra, whereas in others it can be seen in cranial view.
(30) Metapophyses in third lumbar vertebra anterior to last (Fig. 13): 0 = absent; 1 = anterior; 2 = dorsal
(31) Caudal vertebrae, count: 0 = 9 or fewer; 1 = 11 or more.
(32) Caudal vertebrae, hyperexpanded chevrons (Fig. 14): 0 = absent; 1 = present. The character state "present" refers to the condition in which the chevron bones are as wide as the vertebral bodies. Those taxa with condition "1" also display proximal and distal expansions.
(33) Prehensile tail: 0 = absent; 1 = present.
(34) Sternal cartilages, ossification (= sternal ribs): 0 = absent; 1 = present.
(35) Ribs, articulation with sternum (Fig. 15): 0 = with single sternebra; 1 = with two sternebrae.
(36) Coracoid process*: 0 = separate and large; 1 = hook-like process; 2 = small process; 3 = small pedicle or absent.
(37) Ventral extension of acromion: 0 = ventral (beyond) glenoid; 1 = does not extend beyond level of glenoid.
(38) Crest on medial aspect of scapula, near the caudal border: 0 = absent; 1 = present. This crest probably serves as attachment for triceps brachii m. and the teres muscles.
(39) Separate large interclavicle: 0 = absent; 1 = present.
(40) Infraspinous fossa width*: 0 = less than 1/4 its length; 1 = between 1/2 and 1/4 its length; 2 = more than 1/2 its length. The width of the infraspinous fossa was measured as maximum width perpendicular to scapular spine.
(41) Scapular spine width at neck level*: 0 = narrower than infraspinous fossa; 1 = subequal; 2 = wider than infraspinous fossa.
(42) Infraspinous/supraspinous fossa width at neck level*: 0 = infraspinous fossa narrower; 1 = subequal; 2 = supraspinous fossa narrower.
(43) Humerus, medial relief for teres major m.: 0 = absent; 1 = present. The presence of a rugosity, prominence, or ridge was scored as "1." The condition in Phalanger maculatus is absent, that in P. celebensis (AMNH-107999, 108000) is present.
(44) Humerus, lateral ridge: 0 = absent; 1 = ridge or crest; 2 = massive crest continuous with deltopectoral crest.
(45) Humerus, capitulum for radius: 0 = spherical; 1 = cylindrical.
(46) Humerus, entepicondylar foramen: 0 = absent; 1 = present.
(47) Humerus, olecranon fossa or foramen* (Fig. 16): 0 = absent; 1 = fossa; 2 = large fossa; 3 = foramen. This character was coded as "1" when a fossa is present but when its boundaries are not delimited proximally or it was narrower than the distal articular surface of the humerus in distal view. Coding “2” was assigned to fossae that fulfill both conditions (they are delimited around their whole perimeter and were as wide as the distal articular surface of the humerus in posterior view).
(48) Humerus, laminar supinator crest: 0 = absent; 1 = present.
(49) Humerus, greater tuberosity height relative to humeral head height: 0 = equal or greater tuberosity is lower; 1 = greater tuberosity is higher.
(50) Humerus, extension of the deltoid crest: 0 = restricted to proximal half of humerus; 1 = reaches distal half.
(51) Humerus trochlea: 0 = absent; 1 = present.
(52) Humerus, proximal extension of capitulum and trochlea*: 0= longer proximal extension of trochlea; 1 = equal; 2 = longer proximal extension of capitulum.
(53) Humerus, medial epicondyle size: 0 = small; 1 = large. We measured the mediolateral size of the medial epicondyle and divided it by that of the proximal epiphysis of the humerus. Values equal to 0.44 or larger were coded as "large," and values equal to 0.4 or smaller were coded as "small." The medial epicondyle is small in Didelphis marsupialis but large in D. virginiana.
(54) Humerus, distal end size: 0 = small; 1 = large. We computed a quotient between the mediolateral size of the distal epiphysis of the humerus excluding the medial epicondyle and the proximal epiphysis. Quotients equal to 0.85 or smaller were considered "small" and those equal to 0.9 or larger were considered "large."
(55) Humerus, head shape: 0 = symmetrical/ovoid; 1 = mediolaterally compressed.
(56) Humerus, capitulum lateral extension: 0 = absent; 1 = present. An extension is recorded when the articular surface extends beyond a rounded or cylindrical capitulum, in the shape of a raised edge, or a groove and an additional shelf.
(57) Humerus, shaft curvature: 0 = straight; 1 = curved. Our treatment of this character was inspired by that of Munson (1992, ch. # 14), but our coding is different from hers. Since we found a gradient with no clear breaks among most of the taxa examined, we decided to code any degree of curvature as present and absence thereof as absent. The curvature of the posterior side of the shaft was evaluated in medial view.
(58) Ulna, proximal epiphysis, distal most portion of articular surface for humerus: 0 = ulnar area is less than 1/2 of radial one; 1 = more. This portion of the ulnar articular surface was coded as “0” when its area was less than half the size of the radial proximal articular surface. If it was larger, it was coded as "1."59) Ulna, coronoid process: 0 = absent; 1 = present.
(60) Distal process of ulna: 0 = spherical, contributing to a ball and socket articulation; 1 = non-spherical.
(61) Radius, articular facet for humerus (Fig. 17): 0 = circular; 1 = antero-posteriorly compressed.
(62) Lunate: 0 = absent; 1 = very small; 2 = relatively large, with contacts with other carpals. Absence implies either total reduction or fusion with another carpal. Vombatus ursinus was coded as polymorphic because Flower (1867) claimed it is present in some individuals, although the lunate was not observed in the specimen examined (LACM 54089).
(63) Prepollex: 0 = absent; 1 = present. We coded the prepollex absent in Notoryctes based on Szalay (1994, cf. fig. 3.2). Szalay and Sargis (2001, fig. 15) illustrated the prepollex as present in Dromiciops. We have not found the prepollex in any of the adult macerated skeletons examined, including MVZ-163432 and FMNH-129804. The prepollex is also missing in a histologically sectioned juvenile specimen of Dromiciops gliroides (Sánchez-Villagra and Döttling, submitted). Absence of prepollex in Dasypus was coded following Flower (1867); absence in Ornithorhyncus was coded following Ji et al. (2002).
(64) Distolateral process of scaphoid separates dorsally lunate from magnum*: 0 = absent; 1 = present; 2 = present, separates dorsally lunate from magnum.
(65) Proximal aspect of magnum (Fig. 18): 0 = single head; 1 = saddle-shape articulation with lunate. The magnum of Vincelestes was described by Rougier (1993). In Notoryctes, the magnum is most likely fused to the scaphoid.
(66) Magnum, facet with MC III: 0 = flat, convex or kealed; 1 = fully concave.
(67) Trapezium, number of distal heads (Fig. 19): 0 = none or one; 1 = two heads.
(68) Plane of the articular surface trapezium - Mc I in relation to other carpal / metacarpal articulations: 0 = not parallel; 1 = somewhat parallel.
(69) Both MC I and MC V are hyper-reduced in relation to other metacarpals: 0 = hyperreduction; 1 = no hyperreduction.
(70) Magnum and unciform proximal extension: 0 = similarly proximal; 1 = unciform more proximal.
(71) Tuberosity for the rectus femoris m: 0 = no relief; 1 = protuberance; 2 = depression.
(72) Relative size of obturator foramen: 0 = smaller or equal to acetabulum; 1 = larger than acetabulum.
(73) Hyperdevelopment of iliopubic process (Fig. 20): 0 = absent; 1 = present. Among the marsupials examined, the iliopubic process is hyperdeveloped only in the macropodoids. Given the larger size of these in comparison with the other taxa included in the phylogenetic analysis (the wombat and the koala notwithstanding), one might suspect that this character might be allometric. Smaller kangaroos such as Bettongia penicillata, however, also show this hyperdevelopment, which is lacking in the large dasyurid Sarcophilus laniarius.
(74) Contact between ischium and vertebral column: 0 = absent; 1 = present.
(75) Pelvis, acetabular notch: 0 = absent; 1 = present.
(76) Epipubic bones: 0 = absent; 1 = present.
(77) Epipubic bones proximal size: 0 = short; 1 = long. The coding "0" was applied to cases where the contact extent is equal to or less than half the distance that between the pubic symphysis and the point at the anterior edge of the pelvis which is level with the middle of the acetabulum; the coding "0" was applied to cases where the contact is larger.
(78) Mediolateral constriction in greater trochanter of femur: 0 = absent; 1 = present.
(79) Relative height of greater trochanter / femoral head: 0 = greater trochanter is lower or equal; 1 = higher. To code this character, the femoral capitula were positioned on a horizontal surface (rather than orienting the femoral shaft o a perfectly vertical plane). The Caenolestes femora available to us were in a precarious condition, therefore our coding of this taxon is based on illustrations by Osgood (1921, cf. plate 12, fig. 1).
(80) Femur, lesser trochanter (Fig. 21): 0 = absent; 1 = present. A small bump in the area of the lesser trochanter was coded as "absent" for this character.
(81) Fibula proximal medial accessory shelf (Fig. 22): 0 = absent; 1 = present. In some cases the fibula articulates with the tibia through a facet located on a process or shelf that projects medially from the medial surface of the proximal fibula. In others, this projection is missing and the fibula displays a facet located directly on the proximal surface of the fibula.
(82) Fibula proximal posterior extension beyond the area of contact with the tibia: 0 = does not extend posteriorly; 1 = extends. The fibula may be very wide anteroposteriorly in its proximal end. In cases where it is very wide, it extends posteriorly to the facet of contact with the tibia.
(83) Fibula lateral distal process: 0 = absent; 1 = present. The fibula may display a non-articular lateral process in its distal end.
(84) Articulation between femur and fibula: 0 = absent; 1 = present.
(85) Process on fibula proximal end extends proximally beyond knee: 0 = absent; 1 = present.
(86) Sesamoids in articular area between tibia, fibula, and astragalus (or UAJ, upper ankle joint)* (Fig. 4): 0 = absent; 1 = one sesamoid present; 2 = two sesamoids present.
(87) Tibia and fibula distal fusion: 0 = absent; 1 = present.
(88) Tibia medial malleolus: 0 = absent; 1 = present.
(89) Tibia length relative to femur length: 0 = tibia shorter than femur; 1 = tibia longer or equal to femur.
(90) Tibia proximal dimensions*: 0 = larger mediolaterally than anteposteriorly; 1 = equal; 2 = smaller mediolaterally than anteroposteriorly.
(91) Tibia posterior shelf*: 0 = absent; 1 = present but does not extend posteriorly beyond the medial astragalotibial facet; 2 = present and extends posteriorly beyond the medial astragalotibial facet. The posterior shelf of the tibia (Szalay, 1994) is the region in the distal and posterior end of the tibia, directly posterior to the lateral tibioastragalar facet.
(92) Tibia, distal articulation type: 0 = sagittal; 1 = spiral. The types of upper ankle joint can be classified in two general categories, one in which the tibia moves mostly anteroposteriorly or along a sagittal plane, and another where the tibia rotates around its own proximodistal axis, in a spiraled fashion.
(93) Tibia, posterior shelf articulation: 0 = not articular; 1 = articular. The posterior shelf may or may not participate in the distal contact of the tibia with the astragalus.
(94) Astragalus, angle between medial and lateral facets for tibia*: 0 = 90 degrees; 1 = intermediate; 2 = 180 degrees.
(95) Astragalonavicular facet extends on medial side of head: 0 = absent; 1 = medial.
(96) Astragalonavicular facet extends on ventromedial area of head: 0 = absent; 1 = present.
(97) Astragalus, dimensions of facet for navicular in distal view: 0 = transversely wider; 1 = dorsoventrally wider.
(98) Astragalar medial plantar tuberosity (ampt) visibility in dorsal view: 0 = not visible; 1 = visible. In some cases, the ampt is large enough as to form a proximal projection, which one can see in dorsal view, with the medial part of the astragalar body extending proximally beyond the lateral area.
(99) Astragalus, angle between facet for fibula and lateral facet for tibia* (Fig. 23): 0 = 180 degrees; 1 = intermediate; 2 = 90 degrees.
(100) Astragalar neck: 0 = absent; 1 = present.
(101) Astragalus, relative width of head and neck: 0 = neck narrower or as wide as head; 1 = neck wider than head.
(102) Astragalar sustentacular facet medial extent: 0 = does not reach medial edge of neck; 1 = reaches medial edge of neck.
(103) Astragalonavicular facet position relative to facets for tibia: 0 = anterior to facets for tibia; 1 = medial relative to facets for tibia.
(104) Astragalar canal: 0 = absent; 1 = present. The astragalar canal runs from the posterior area of the lateral facet for the tibia to the ventral surface of the astragalus, just anterior to the posterior astragalocalcaneal facet.
(105) Posterior astragalocalcaneal facet major dimension orientation*: 0 = anteromedial to posterolateral; 1 = straight; 2 = posteromedial to anterolateral.
(106) Posterior astragalocalcaneal facet position in ventral view: 0 = extending up to posterior edge of astragalus; 1 = subterminal.
(107) Astragalus, ridge between medial and lateral astragalotibial facets: 0 = absent; 1 = present.
(108) Astragalus, ridge between lateral astragalotibial and astragalofibular facets: 0 = absent; 1 = present.
(109) Medial astragalotibial facet, posterior extent: 0 = does not reach posterior edge of lateral astragalotibial facet, 1= equal in anteroposterior length as lateral astragalotibial facet.
(110) Astragalonavicular facet connection with sustentacular facet: 0 = absent; 1 = present.
(111) Calcaneal sustentacular facet on sustentaculum* (Fig. 24): 0 = no sustentaculum (facet is located in calcaneal body); 1 = on sustentaculum; 2 = facet is located above level of sustentaculum, which becomes the medial process.
(112) Calcaneal sustentaculum position: 0 = subterminal; 1 = on anterior end. The sustentaculum can be located with its anterior edge coinciding with the anterior edge of the body of the calcaneum, or at a distance from the anterior edge of the calcaneum.
(113) Ectal (or posterior calcaneoastragalar facet) longest dimension*: 0 = anteromedial to posterolateral; 1 = straight; 2 = posteromedial to anterolateral.
(114) Ectal (or posterior calcaneoastragalar facet) longest axis when straight: 0 = sagittally longer; 1 = transversely longer. When the previous character is scored as "1 = straight," this condition was considered here for scoring in the two alternative varieties. All other conditions of the previous character were inapplicable here.
(115) Calcaneal anterior peroneal tubercle: 0 = absent; 1 = present.
(116) Calcaneal anterior peroneal tubercle shape: 0 = protuberance; 1 = laminar; 2 = process.
(117) Calcaneal anterior peroneal tubercle position*: 0 = protruding anteriorly beyond calcaneocuboid facet; 1 = anterior, non-protruding; 2 = at a distance from anterior end of calcaneum.
(118) Calcaneal sustentacular facet mesiolateral orientation: 0 = medial; 1 = dorsal. The sustentacular facet was scored as medial when at least the anterior area is directed medially, even if more posteriorly it curves to facing somewhat more dorsally.
(119) Calcaneal sustentacular facet anteroposterior orientation: 0 = dorsal; 1 = 45 degrees dorsoanteriorly. This character was only coded for taxa having ch. 118 .
(120) Calcaneal sustentacular facet convex anteroposteriorly: 0 = concave or flat; 1 = convex.
(121) Calcaneal sustentacular facet posteriorly convex: 0 = absent; 1 = present. Coding done only on taxa which displayed "0" for previous character.
(122) Calcaneal plantar tubercle: 0 = absent; 1 = present.
(123) Calcaneal sustentacular facet and posterior calcaneoastragalar facets merging*: 0 = separate; 1 = with narrow connection; 2 = merged (Fig. 6).
(124) Calcaneal sustentacular facet anterior edge (Fig. 6): 0 = anterior to posterior facet; 1 = equal or posterior to posterior facet.
(125) Calcaneal facet for fibula: 0 = absent; 1 = present.
(126) Calcaneal facet for fibula orientation: 0 = lateral; 1 = dorsal. Inapplicable for those scored ch. 125 .
(127) Calcaneal notch for cuboid pivot (see cuboid in Fig. 3): 0 = absent; 1 = present.
(128) Calcaneum sustentacular facet reaches anterior end: 0 = absent; 1 = present.
(129) Calcaneum accessory facet anterior to sustentacular facet: 0 = absent 1 = present. Described by Szalay (1994), this facet displays a different orientation from that of the sustentacular facet, which distinguishes one from the other.
(130) Cuboid medial plantar process forms groove (Fig. 3): 0 = absent; 1 = present. The cuboid medial plantar process in some cases displays a hook-like shape, forming an almost enclosed canal for the tendon of the peroneus longus m. (Szalay, 1994).
(131) Cuboidcalcaneal facet: 0 = mostly convex or flat; 1 = concave anteroposteriorly; 2 = two shelves, medial more proximal; 3 = two concavities.
(132) Cuboidcalcaneal facet angle between proximal and distal facet areas* (Fig. 3): 0 = no angle; 1 = present, dorsal area narrow; 2 = present, dorsal wider than width of proximal.
(133) Cuboidcalcaneal facet outer shelf (Fig. 3): 0 = absent; 1 = present.
This shelf is concave, and surrounds the more proximal area of the facet at least on the dorsal area of the bone.
(134) Cuboidcalcaneal ventral facet: 0 = absent; 1 = present. In macropodoids there is a partially isolated facet on the ventral area of the articular surface of the cuboid with the calcaneum.
(135) Spatial relationship between navicular and entocuneiform: 0 = entocuneiform anterior to navicular; 1 = entocuneiform extends proximally medial to the distal area of the navicular.
(136) Navicular shelf between cuboid and astragalus (Fig. 5): 0 = absent; 1 = present. In Notoryctes and the peramelians Echymipera and Perameles the navicular extends between the cuboid and the astragalus, making contact with the calcaneum and forming a physical barrier between the astragalar head and the cuboid.
(137) Navicular size*: 0 = navicular half to one third the size of the cuboid; 1 = navicular more than half the size of the cuboid to equal to it; 2 = navicular larger than the cuboid.
(138) Mesocuneiform contact with navicular: 0 = absent; 1 = present.
(139) Falcula on hallux: 0 = absent; 1 = present.
(140) Prehallux: 0 = absent; 1 = present.
(141) Mt IV proximal contact (Fig. 8): 0 = ectocuneiform and cuboid; 1 = cuboid.
(142) Mt V proximal process extends ventral to cuboid: 0 = not ventral; 1 = ventral.
(143) Mt II and Mt III proximal ends*: 0 = Mt II extends more proximally than Mt III; 1 = equal; 2 = Mt III more proximal.
(144) Hallux opposability (articulation Mt I with entocuneiform): 0 = not opposable; 1 = opposable.
(145) Ridge on proximal articular facet of Mt I: 0 = absent; 1 = present.
(146) Syndactyly or external fusion of digits II and III in the foot: 0 = absent, 1 = present.
(147) Mt III thickness relative to that of Mt IV: 0 = Mt III thinner; 1 = Mt III and IV equal thickness or Mt IV thicker.
(148) Mt III thickness relative to that of MtI*: 0 = Mt III thinner; 1 = Mt III and I equal ; 2 = Mt III thicker than Mt I; 3 = Mt I absent.
(149) Foot ungual phalanx of digit IV, proximal view*: 0 = larger dorsoventrally than mediolaterally; 1 = equal dimensions; 2 = larger mediolaterally than dorsoventrally.