Rapid Pliocene Diversification of Modern Kangaroos
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1 Supplementary Materials for: 2 3 RAPID PLIOCENE DIVERSIFICATION OF MODERN KANGAROOS 4 5 Materials and Methods: 6 7 EXPERIMENTAL DESIGN 8 9 Molar Crown-Height Measurement 10 11 Molar crown-height was measured on modern and fossil molar teeth from the Australian 12 Museum (Sydney), Australian National Wildlife Collection (Canberra), Flinders University 13 Paleontology Laboratory (Adelaide), Museum Victoria (Melbourne), Queensland Museum 14 (Brisbane), South Australian Museum (Adelaide), Museum of Central Australia (Alice 15 Springs), and Western Australian Museum (Perth). Crown-height was measured using digital 16 calipers on unworn (or molars with only slight wear) from the base of the enamel cap 17 vertically to the hypoconid apex. We restricted analysis to second and third molars both 18 because these tend to be the least variable and also represent the key functional teeth during 19 the animal’s lifetime. We divided the molar crown-height measurement by the maximum 20 talonid width to compute a crown-height ratio (here forth referred to as “crown-height”). 21 Talonid width was used as a standardization for tooth size because it is strongly correlated 22 with other proxies for macropodoid body size such as condylobasal or total skull (33). 23 Major–axis regression with lmodel2 was used to test trait correlations in R. 24 25 Dental Macrowear Scoring 1 26 Macrowear was scored using a modified version (fig. S1) of a dental exposure scheme (34) 27 initially developed for the eastern grey kangaroo. To more fully accommodate the variation in 28 wear patterns across Macropodoidea we appended six additional wear patterns which we 29 encountered (figs. S1,2). Our aim was to establish comparable levels of dental wear across 30 diverse kangaroo dentitions rather than to completely describe the diversity of wear patterns 31 within Macropodoidea. All specimens except those from the Hamilton Local Fauna (LF) 32 were scored by AMCC based on direct inspection or occasionally from high-resolution 33 occlusal photographs when specimens could not be inspected. We compared wear levels 34 scored between GJP and AMCC and found differences to be negligible. Teeth were scored in 35 occlusal view within one of eight dentine exposure categories ranging from unworn (0) to 36 heavily worn (7). Teeth with extremely small (incipient) planar facets along the posterior 37 loph edge which did not propagate to the cusp apices were scored as unworn. Dentitions were 38 sampled randomly with respect to wear although where possible we avoided measuring 39 isolated teeth if complete dentitions were available so we could be confident with tooth 40 position assignments. Although we measured macrowear on all molar teeth we restricted 41 analysis to second and third mandibular molars both in order to compare animals of similar 42 age and because first and fourth molars tend to show more variable and sometimes distinct 43 wear patters. 44 45 2 46 47 Fig. S1. Molar macrowear levels (modified after 34) used to classify fossil and modern 48 macropodoid teeth. 49 50 3 51 52 Fig. S2. Uncommon patterns of variation in macrowear levels recognised among living and 53 fossil macropodoids. 54 55 STASTICAL ANALYSIS 56 57 General Data Processing 58 59 A paired-sample T-test revealed significant differences between third mandibular molar (M3) 60 crown-height measured at the protoconid compared with the hypoconid (T110=−5.632, 61 p<0.01). Analysis was subsequently restricted to crown-height measured at the better 62 sampled hypoconid of second and third molars. We digitized taxonomy, age and site 63 description data for each tooth specimen measured. Each specimen was assigned an 64 estimated, maximum and minimum age based on a rigorous review of geological and 65 biostratigraphic data (table S1). Assigned sub-epoch bounds follow (35). Taxonomic 66 assignments were compared against those in the literature or amended where necessary. 67 68 Linear Modelling of Extant Molar Crown-Height Variation 69 70 A linear modelling approach was used to examine the correlation between molar crown- 71 height, diet and habitat variables amongst modern kangaroo species as a baseline for the 4 72 ecological interpretation of fossil crown-height data. Diet and habitat variables were drawn 73 from literature sources (table S2). To estimated habitat parameters preferred feeding habitat 74 (PFH) was used based on (36), but the number of variables was collapsed to avoid over- 75 penalizing the model. Modelling was performed in a phylogenetically-adjusted context by 76 building alternative Pagel’s lambda (λ) transformations of a macropodoid molecular 77 phylogeny (9) and trait data into the linear model (i.e., 37) using pgls in caper (38). The 78 full linear model comprising two non-interacting, dependent-variable terms (diet + preferred 79 feeding habitat) was compared with a reduced model with habitat removed using sample- 80 size-adjusted Akaike information criterion weights (AICc) (39). Assumptions of the linear 81 model were validated using various model diagnostics including homogeneity of the residuals 82 and distribution of the response variable. Homogeneity of the residuals (against fitted values) 83 improved visually after the maximum-likelihood value of λ was applied. A correlation test 84 found no significant relationship between fitted values and the phylogenetically-transformed 85 residuals (T15=0.08, p>0.05) supporting inspection of a quantile–quantile plot. 86 87 88 89 5 90 91 Table S1. Biostratigraphy and age constraints for 99 Australian fossil sites from which macrowear and molar crown-height date was measured. 92 Assemblage Australian Local fauna Subepoch Max Maximum-age error Estimated- Estimated-age Minimum- Minimum-age error Land age remarks age remarks age remarks Mammal Age AL90, Riversleigh, Camfieldian AL90 Middle 15.100 Radioisotopic date 14.730 Radioisotopic date 14.170 Radioisotopic date range NW QLD Miocene range (40). average (40). (40). Alcoota, central Waitean Alcoota Late 11.608 Late Miocene range 7.000 Estimate from (32). 5.332 Late Miocene range (35). NT Miocene (35). Constrained by minimum Early Pliocene age of overlying Ongeva LF. Awe, NE PNG Tirarian? Awe Late 3.300 Maximum 2.900 Awe is K–Ar dated to 2.500 Minimum radiometric Pliocene radiometric age. 2.9+-0.4 Myr (41). age. Big Sink, Tirarian Big Sink Early 5.332 Miocene–Pliocene 4.000 (42) 2.580 Plio–Pleistocene Wellington, NSW Pliocene boundary. boundary. Allingham Tirarian Bluff Downs Early/middle 5.332 Miocene–Pliocene 3.600 Assume approximate 3.600 Overlaying basalt age Formation, Pliocene boundary. age of overlying (43). Allingham Creek, basalt. 6 Bluff Downs, NE QLD Boid, Riversleigh, Wipajirian Boid Early 25.000 Etadunnan– 17.010 Average of 17.000 Approximate NW QLD Miocene Wipajirian boundary. Wipajirian Wipajirian–Camfieldian assemblages dated boundary (32). by (40). Boid Site East, Wipajirian Boid Site Early 25.000 Etadunnan– 17.010 Average of 17.000 Approximate Riversleigh, NW East Miocene Wipajirian boundary. Wipajirian Wipajirian–Camfieldian QLD assemblages dated boundary (32). by (40). Boles Bonanza, Wipajirian Boles Early 25.000 Etadunnan– 17.010 Average of 17.000 Approximate Riversleigh, NW Bonanza Miocene Wipajirian boundary. Wipajirian Wipajirian–Camfieldian QLD assemblages dated boundary (32). by (40). Bow, near Tirarian Bow Early/middle 5.332 Miocene–Pliocene 3.600 Assume similar age 2.580 Plio–Pleistocene Merriwa, central Pliocene boundary. to Bluff Downs LF boundary. NSW (44). Bullock Creek, Camfieldian Bullock Middle 17.000 Wipajirian– 14.500 Median age of 12.000 Camfieldian–Waitean central NT Creek Miocene Camfieldian Camfieldian. boundary. boundary. 7 Camel Sputum, Wipajirian Camel Early 18.530 Wipajirian 17.750 Radioisotopic date 16.970 Wipajirian radioisotopic Riversleigh, NW Sputum Miocene radioisotopic date average (40). date range (40). QLD range(40). Cathedral Cave, Naracoortean Cathedral Middle 0.780 Early–middle 0.300 Approximate age of 0.206 Minimum optical age of Naracoorte Cave Pleistocene Pleistocene most faunally diverse Unit 1 (45). region, SE SA boundary. interval (Unit 3) (45). Childers Cove, Naracoortean Childers Early 2.580 Plio–Pleistocene 1.000 Approximate age 0.780 Estimated based on western VIC Cove Pleistocene boundary. based on biocorrelation. biocorrelation. Chinchilla, SE QLD Tirarian Chinchilla Late 3.600 Based on late 3.090 Median age of late 2.580 Estimated based on Pliocene Pliocene Pliocene. biocorrelation. biocorrelation. COA1, Riversleigh, Wipajirian Cleft of Ages Early 25.000 Etadunnan– 18.500 Median age of 12.000 Camfieldian–Waitean NW QLD 1/2A Miocene Wipajirian boundary. Camfieldian boundary. +Wipajirian land mammal ages. Creasers Rampart, Wipajirian Creasers Early 25.000 Etadunnan– 17.010 Average of 17.000 Approximate Riversleigh, NW Rampart Miocene Wipajirian boundary. Wipajirian Wipajirian–Camfieldian QLD assemblages dated boundary (32). by (40). 8 Corra Lynn Cave, Tirarian? Curramulka Late 5.332 Miocene–Pliocene 3.090 Median age of late 2.580 Plio–Pleistocene Yorke Peninsula, Pliocene boundary. Pliocene. boundary. SA Darling Downs, SE Naracoortean Darling Late 0.780 Early–middle 0.100 Generic Late 0.012 Minimum-age based QLD Downs Pleistocene Pleistocene Pleistocene age Holocene–late boundary. based on Pleistocene boundary. biocorrelation. Dirks Towers 6,7, Wipajirian Dirks Towers Early 25.000 Etadunnan– 17.010 Average of 17.000 Approximate Riversleigh, NW 6,7 Miocene Wipajirian boundary. Wipajirian Wipajirian–Camfieldian QLD assemblages dated