Appendix Morphological character list Form of upper incisors

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Appendix 1. Morphological character list

  1. Form of upper incisors. In most lemurs, the upper incisors have a club-like shape; i.e. they are expanded mesially, and sometimes show a small heel (0). The incisors of Aotus are also assigned to this category. In most of the remaining taxa, the incisors are peg-like, and the tips are no wider than the roots (1). In Lepilemur spp. there are generally no upper incisors at all in the adult stage, although an adult specimen in the AMNH collection (100622) shows a relictual peg-like left upper incisor and a socket for a similarly sized tooth on the right. Juvenile and subadult skulls in the NHM collection (e.g., often have two similar peg-like incisors, one on either side of the incisive foramina, and lepilemurs are therefore coded as (1). In Daubentonia the upper incisors are chisel-shaped (3), while in tarsiers they are caniniform (4).

  2. Relative lengths of incisors. In most Malagasy strepsirhines and in Tarsius and Aotus, the medial incisors are 2 to 3 times the length of the lateral incisors (0). This condition occurs solely in Nycticebus among the lorisoids, where the I2 may be lost altogether. Similar extreme reduction of the lateral incisors occurs occasionally in other strepsirhine taxa (see character 3). In all other lorisoids the I1 and I2 are subequal in length (1). In Daubentonia the lateral incisor is permanently lost (2) and in Lepilemur spp. both incisors are lost in the adult stage (3).

  3. Width of inter-incisor gap. In Daubentonia, Aotus and Tarsius the roots of the anterior teeth are separated by a very small, “pinched” gap (0), while the crowns are closely approximated. In all living strepsirhines the medial incisors are separated by a gap that links the rhinarium directly to the vomeronasal organ [Schilling, 1980]. However, the width of the gap varies [Asher, 1998], as does the degree of intrusion of the incisive foramina between the I1s. In most taxa, the gap is approximately the width of two slender incisors (1). In gregarious strepsirhines, as well as in the specialist gummivore Phaner, the gap is wider and can accommodate three or four incisors (2). In Lepilemur spp., the absence of upper incisors coincides with the expansion of the incisive foramina, and has therefore been coded as a wide gap. This “crowding out” of the upper incisors by the incisive foramina occurs in many lemuroid and lorisoid taxa, to the extent that the lateral incisors may be lost (e.g., as seen occasionally in Avahi, Cheirogaleus, Eulemur, Galago, Hapalemur and Nycticebus).

  4. Shape of anterior palatal margin. In many strepsirhine species the anterior margin of the palate forms a steep arch, and the I2s stand behind the I1s (0). This is a condition similar to that seen in tree shrews and other non-primate mammals [Martin, 1990]. Although Daubentonia has only one pair of incisors, their major axes are oriented along the lines of a steep arch, and are therefore coded 0. In most of the remaining strepsirhines and in Aotus and Tarsius, the upper incisors are disposed next to one another along a gentle curve (1). In Lepilemur the anterior margin is straight (2).

  5. Excavation of anterior palatal margin. In most living strepsirhines and in the outgroup taxa, there is no excavation of the anterior palatal margin (0). In indriids the margin shows a marked V-shaped excavation at the junction of the premaxillae, a structural feature that is likely to be linked to vomeronasal function (1). The Eocene adapiform Adapis parisiensis had a similar V-shaped excavation [Beard, 1988, fig. 2].

  6. Presence of tooth-comb. A tooth-comb, in the form of elongated, horizontally-rotated elements in close proximity to one another, is present in all living strepsirhines with the exception of Daubentonia. While some have argued that Daubentonia’s rodent-like anterior dentition evolved from a tooth-combed ancestor [Martin, 1990; Ankel-Simons, 1996], others disagree [Luckett and Maier, 1986; Luckett, 1993]. In the absence of resolution, the state shared with the outgroups (tooth-comb absent) is coded 0, while tooth-comb present is coded 1.

  7. Number of teeth in tooth-comb. In the outgroups and Daubentonia, no teeth are included in a tooth-comb (0). In the majority of strepsirhines, the tooth-comb is made up of six teeth: four incisors and two canines (1). In indriids, the tooth-comb consists of only four teeth (2).

  8. Orientation of lower incisors. In Aotus and Tarsius the anterior incisors are almost vertically implanted (0). In most living strepsirhines the lower incisors are incorporated into a tooth-comb which has an orientation of 20° - 40° to the horizontal (1). In lorisids the tooth-comb is much more steeply angled, about 60° (2).

  9. Premaxillary extension. In most living strepsirhines, owl monkeys and tarsiers there is very little extension of the premaxillae beyond the incisor tooth row (0). In some lorisoids there is a mild degree of premaxillary extension (1), while in others the premaxillae are markedly extended beyond the tooth row to form a rostral tube (2).

  10. Number of P2 roots. In Aotus and most living strepsirhines the upper anterior premolar has marked anterior and posterior styles, and is double-rooted (0). In tarsiers, cheirogaleids and some lorisoids, the upper anterior premolar is caniniform with reduced styles, and a single root (1). In indriids and Daubentonia, the P2 is missing altogether (2).

  11. Relative height of P2. In owl monkeys, tarsiers and many strepsirhine taxa the P2 is no taller than the other post-canine teeth (0). In some lorisoid taxa the P2 is clearly taller than the P3 (1), while in some highly gummivorous taxa (Phaner, Allocebus), the P2 has become greatly enlarged and caniniform in shape (2). In indriids and Daubentonia the P2 is missing altogether (3).

  12. Relative development of P3. In owl monkeys, tarsiers and most strepsirhines the P3 is of an equivalent development to the anterior premolar (0). In lemurids, with the exception of the bamboo lemurs, the P3 is noticeably larger than its neighbours [Mivart, 1873] (1). In Daubentonia this tooth is lost permanently (2).

  13. Orientation of P2. In many strepsirhine taxa the lower anterior premolar is semi-procumbent, angled in the direction of the procumbent toothcomb (0). In some taxa, the P2 is erect and tusklike (1). A vertical orientation also occurs in Aotus and Tarsius. In Daubentonia this tooth is absent (2).

  14. P3 lingual cingulid. This is strongly developed in most lemuroids, lorisids and tarsiers (0), but very weakly developed in some eulemurs and in all galagids, to the point where it may be difficult to detect (1). It is also missing in Aotus. In Daubentonia and indriids the whole tooth is lost (2).

  15. Position of infraorbital foramen. In most living strepsirhines the infraorbital foramen is positioned above the junction of the P3 and P4 (0). In some taxa, it is shifted further back, and occupies a position closer to the P4 – M1 junction (1). In Aotus and Tarsius, no doubt as part of the reorganization that accompanied the shortening of the face, the foramen is shifted forward to the P2 – P3 junction (2).

  16. Molariform P4. In owl monkeys, tarsiers and most living strepsirhines the posterior premolar is readily distinguishable from the molar array (0). In bamboo lemurs and galagids, the P4 is molariform, as large or even larger than the M3 (1). In Daubentonia, too, the only premolar is similar in form (but not in size) to the molars, and is coded as molariform (1).

  17. Extent of M3 occlusal surface. In tarsiers and most lemuroids the posterior upper molar lacks a hypocone (0). In owl monkeys and most lorisoids, the M3 has a similar occlusal surface to the other molars (1). In the larger indriids, it is the buccally-situated metacone that is reduced (2).

  18. Extent of M3 occlusal surface. In Tarsius and the majority of living strepsirhines, the M3 has a posterior lobe bearing a distinct hypoconulid (0). In some taxa, including Aotus, the last lower molar is reduced in size, and shows no such extension (1).

  19. Cusp height. Some taxa, like Cheirogaleus and Aotus, are remarkable for their low molar cusps (0). Others have cusps of intermediate height (1), while those of the more insectivorous/faunivorous and folivorous taxa have high cusps (2).

  20. Degree of orbital frontation. In most taxa, the orbits do not have a marked forward rotation, and the postorbital bars do not extend laterally beyond the zygomatic arch (0). In tarsiers, owl monkeys, indriids, Loris and some members of the genus Galago, they do (1).

  21. Exposure of ethmoid on medial orbital wall. Groves [1974] and Cartmill [1975] observed that the ethmoid is not exposed on the medial orbital wall in most lemuroids and known adapiform skulls, even small adapiforms like Pronycticebus (0). However, the ethmoid is exposed in all cheirogaleids except Phaner, and in all lorisoids, as well as in haplorhines (1). Cartmill [1975] viewed ethmoid exposure as “at least partly conditioned by allometry and orbital convergence.”

  22. Snout length relative to orbit width. In lemurids (with the exception of the bamboo lemurs), as in most mammals, the snout is much longer than the orbit width (0). In most living strepsirhines, the snout length is equivalent to the orbit width (1). In taxa like Loris, Aotus, Tarsius, and in most galagos, the snout is much shorter than the orbit width (2).

  23. Junction of postglenoid plate and auditory bulla. In most living strepsirhines and in Aotus, the junction between the postglenoid plate and the bulla is marked by a clear fissure (0). In some taxa (cheirogaleids, Lepilemur, most lorisids, Tarsius) [Tattersall and Schwartz, 1975], the plate is fused medially to the bulla and part or all of the fissure is obliterated (1).

  24. Position of postglenoid foramen. For most extant strepsirhines, the postglenoid foramen is situated on the posterior side of the postglenoid plate (0). In Phaner, Tarsius, Aotus and all lorisids, it has been shifted posteromedially (1).

  25. Fusion of ectotympanic to bulla. In most lemuriforms, the ectotympanic ring is suspended within the bulla cavity, a condition often judged to be ancestral [Gregory, 1915; Szalay, 1975] (0). In Microcebus there is a partial fusion of the ectotympanic to the lateral bulla wall [Charles-Dominique and Martin, 1970; Cartmill, 1975] (1). In Allocebus [Cartmill, 1975], Aotus, Tarsius and all the lorisoids, the ectotympanic is fused to the bulla for all or most of its length (2).

  26. Intrabullar partition separating tympanic and hypotympanic cavities. This character is absent in all Malagasy taxa and the outgroups (0), but present in all lorisoids (1).

  27. Primary internal carotid branch carrying blood to brain. In Aotus and Tarsius, as in all haplorhines, the promontory artery is the primary vessel supplying blood to the brain (0). In the majority of living lemuroids (as well as the Eocene adapiforms), the stapedial branch of the internal carotid serves this function (1).There is fossil evidence that the divergence between stapedial-dominated and promontory-dominated circulation dates at least to the early Eocene (55 Myr), and perhaps earlier [Szalay, 1975]. In lorisoids and cheirogaleid lemuroids, the major vessel serving the brain is an enlarged ascending pharyngeal artery [Cartmill, 1975] (2). The earliest fossil evidence for this circulatory pattern is early Miocene (20 Myr), although it is likely to have been present much earlier.

  28. Reduction of stapedial artery. In the majority of living and extinct strepsirhines, the stapedial artery is the largest conduit of blood to the brain (0). In Lepilemur, cheirogaleids, lorisoids and haplorhines the stapedial is greatly reduced, and may even be absent [Szalay, 1975; Tattersall and Schwartz, 1975] (1).

  29. Width of postorbital bars. Most living strepsirhines have slender postorbital bars (0). In some taxa (e.g. indriids, Galago), the postorbital bars are wider and flanged (1). In Tarsius and Aotus, there is postorbital closure (2).

  30. Shape of lower margin of horizontal mandibular ramus. In most extant strepsirhines, the mandibular corpus is of approximately equal depth along its length [Walker, 1978; McCrossin, 1992] (0). In some lemurs (e.g. indriids, bamboo lemurs, aye ayes), some lorisoids (Nycticebus, Perodicticus) and in owl monkeys, the corpus deepens towards the angle (1).

  31. Length of coronoid process. In the majority of living strepsirhines, the coronoid processes are long, approximately as long as the distance between the articular condyle and the angular process (0). In some taxa, including outgroups Aotus and Tarsius, the coronoids are shorter (1). Character states were assigned on the basis of a glenoid/coronoid index.

  32. Shape of coronoid process. The most common condition is a rounded shape to the coronoid, like a breaking wave (0). In certain taxa (Phaner, Allocebus, lorisids, Daubentonia), the curve of the wave is truncated, and may (as in Phaner and Allocebus) form a sharp point (1). In certain cheirogaleids (Microcebus, Mirza) and some galagids, the coronoid is long, narrow and angled backwards, but not hooked (2). In Tarsius the coronoid is reduced to a small eminence in front of the condyle (3).

  33. Shape of angular process. The angular process varies in shape and development. In Daubentonia it is little more than a bump on the lower edge of the mandible (0). In some taxa (e.g., Phaner, Allocebus, Microcebus, Mirza) it is small, narrow and hooked (1), while in the majority of taxa, it is broader and pointed (e.g. Eulemur, Lemur) (2). Lepilemur shows a similar angular shape to (2), but the process is greatly extended downwards (3). In Aotus, Tarsius, indriids, bamboo lemurs, Nycticebus and Perodicticus it is broad and rounded (4).

  34. Height of the condyle relative to the occlusal surface. In Aotus, Tarsius and the majority of strepsirhine taxa the mandibular condyle is at a height significantly above the occlusal surface of the tooth row (0). In some taxa (e.g. Lepilemur, some cheirogaleids, some galagids, Nycticebus) the condyle is at the same height as, or only slightly above, the occlusal surface (1). Szalay [1968] described a high condyle (0) as indicative of an herbivorous or frugivorous diet, while Vinyard et al. [2003] have linked condition (1) to bark gouging during gum-feeding.

  35. Vertical position of coronoid relative to condyle. In the outgroups and most ingroup taxa (lemurids, indriids, Daubentonia, most lorisids and galagids) the coronoids are orientated vertically, and terminate well forward of the glenoid condyle (0). In some taxa (some cheirogaleids, some galagids), the coronoids extend back to a position above the glenoid condyle (1).

  36. Direction of articular surface of condyle. In Aotus, Tarsius and most strepsirhines, the condyle is directed upwards and tilted slightly backwards (0). In Lepilemur and the indriids there is a double articular surface, one directed upwards (horizontal), and a second on the proximal surface of the condyle angled vertically [see Mivart, 1873, fig. 4; Tattersall and Schwartz, 1975, fig. 3]. This condition was coded 1.

  37. Lateral flexion of coronoid processes. In some taxa (e.g. Hapalemur), the vertical ramus is essentially straight (0). In the majority of strepsirhines it remains straight, but is angled outwards from angle to coronoid (1). In a few taxa, chiefly those practicing gum scraping, the coronoids are flexed laterally (2).

  38. Degree of mastoid inflation. Tarsiers, owl monkeys and most strepsirhines show little or no inflation of the mastoid region (0). Lepilemur and Allocebus share with the lorisoids a degree of mastoid inflation [Mivart, 1873; Cartmill, 1975] (1).

  39. Presence of a peak on the zygomatic arch. The upper margins of the zygomatic arches of the outgroup taxa and most strepsirhines are smooth and straight (0). In some taxa (notably the galagids, but also Phaner and Daubentonia) there is a marked and consistent peak between the postorbital bar and the posterior zygomatic root (1).

  40. Extent of basicranial flexion. In many taxa (e.g. most cheirogaleids, Eulemur species, lorisids) the basicranium is essentially flat (0). In Aotus, Tarsius, bamboo lemurs, Phaner and some galagids, the basicranium shows marked flexion (1).

  41. Relative lengths of the pterygoids. In Aotus, Tarsius and lorisoids, the medial pterygoids are much reduced in length and robustness relative to the laterals (0). In lemuroids, the medial and lateral pterygoids are of equivalent length, although the medial pterygoids may be less robust than the laterals (1).

  42. Longest digit on hand. In Aotus and Tarsius, the third digit of the hand is the longest (0). In some lemuroids, digits III and IV are of equivalent length, with III sometimes slightly surpassing IV (1). In most strepsirhines, the fourth digit is the longest (2).

  43. Shape of nails. The majority of lemuroids (with the exception of Microcebus) have pointed nails on the hands and feet that do not have a well-developed medial keel (0). The nails of Aotus show a similar condition. Lorisoids and the small-bodied cheirogaleid Microcebus have nails that are rounded or ovoid (1). In adult Otolemurs, the nails develop a crescent shape with wear, but the nails of juveniles are like those of other lorisoids, and they are coded 1. A few taxa (Phaner, Allocebus, Lepilemur and Tarsius) have “needle-claws”, i.e. nails with a strongly-marked medial keel ending in a sharp point (2).


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