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Figure 2 in Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

Figure 2. Ventrolateral views of the seven UFRJ-DG petrosal specimens studied in this paper and attributed to cf. Miguelsoria parayirunhor. UFRJ-DG specimen number is indicated below each specimen. Note that specimens UFRJ-DG 347-M and 1036-M have been mirrored in this figure.

Figure 1 in Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

Figure 1. Measurements on the petrosal and second upper molar used in this paper. A, B, measurements on the promontorium (PROM) of the petrosal (PET) and second upper molar (M2) for the regression analysis and attribution of Itaboraí specimens; A corresponds to a posterolateroventral view of the virtually reconstructed petrosal UFRJ-DG 1036-M, and B to an occlusal view of M1−3 of Protolipterna ellipsodontoides DNPM LE444A [modified (mirrored) from Cifelli, 1983b: fig. 4]; C, D, measurements taken on the petrosal for the regression analysis on the scaling effects between the petrosal and bony labyrinth; C, lateroventral view of the same petrosal as in A; D, cerebellar view of the same petrosal. Abbreviations: H, height; L, length; W, width.

Figure 10 in Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

Figure 10. Strict consensus cladogram (518 steps, consistency index = 0.36, retention index = 0.71) of the analysis with 50 taxa searching for the relationships of the UFRJ-DG petrosals under study.

Figure 8. Virtual 3D in Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

Figure 8. Virtual 3D reconstruction and outline drawing of the bony labyrinth of UFRJ-DG 1036-M, details of anatomy in posteromedial view. Abbreviations: aa, anterior ampulla; asc, anterior semicircular canal; av, vestibular aqueduct; can, cochlear canaliculus; cc, common crus; cf, cochlear fossula; co, cochlear canal; fsg, foramen singulare; f sup vest, foramen for the superior vestibule area; lsc, lateral semicircular canal; psc, posterior semicircular canal; scc, secondary common crus; sl. s., secondary bony lamina sulcus; vasc. sulc., impression of vascular sulci left on the bony cochlear canal.

Figure 5. Virtual 3D in Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

Figure 5. Virtual 3D reconstruction and outline drawing of petrosal UFRJ-DG 1036-M (mirrored), details of anatomy; A, cerebellar view; B, dorsal view. Abbreviations: aav, external aperture of the vestibular aqueduct; acan n, notch housing the external aperture of the cochlear canaliculus; cev s?, sulcus for capsuloparietal emissary vein?; circ. fs, (vascular?) circular fossa; cn, canal and cribriform tract for cochlear nerve; cp (br.), crista petrosa (broken); cpa, crista parotica; exs, exoccipital articulation surface of petrosal; fai, foramen acusticum inferius; fas, foramen acusticum superius; ff, facial foramen; fi, fossa incudis; fsa, fossa subarcuata; fsg, foramen singulare; f sup vest, foramen for the superior vestibule area; ips, sulcus of inferior petrosal sinus; lv.ips, crest-like lateroventral border of sulcus for inferior petrosal sinus; md.ips, crest-like mediodorsal border of sulcus for inferior petrosal sinus; obl.g, oblique groove; pg, posterior occipital groove; pmc, petromastoid canal; pr, promontorium; ptn, post-temporal notch; pts, post-temporal sulcus; sps, sulcus of superior petrosal sinus; sqs, squamosal articulation surface of petrosal; st.s., stapedial artery sulcus; tt, tegmen tympani.

Figure 9 in Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

Figure 9. Computed-tomography slices through the isolated petrosal UFRJ-DG 1035-M. Numbers refer to individual slices that are re-located on the virtually reconstructed translucent petrosal and bony labyrinth at the lower right corner. Abbreviations: aa, anterior ampulla; aav, external aperture of the vestibular aqueduct; A.b.X n., notch/sulcus for the auricular branch of the vagus nerve (X); acan n, notch housing the external aperture of the cochlear canaliculus; acf, external aperture of the cochlear fossula; asc, anterior semicircular canal; cc, common crus; cgsn, canal for the ganglion of spiral nerve; cn, canal and cribriform tract for cochlear nerve; co, cochlear canal; fai, foramen acusticum inferius; fn, canal for facial nerve; fs, facial sulcus; fsa, fossa subarcuata; fsg, foramen singulare; f sup vest, foramen for the superior vestibule area; fv, fenestra vestibuli; la, lateral ampulla; lsc, lateral semicircular canal; lv.ips, crest-like lateroventral border of sulcus for inferior petrosal sinus; pa, posterior ampulla; pl, primary bony lamina; psc, posterior semicircular canal; rtp, rostral tympanic process; scc, secondary common crus; sl, secondary bony lamina; ves, vestibule.

Figure 6 in Petrosal and inner ear anatomy and allometry amongst specimens referred to Litopterna (Placentalia)

Figure 6. Dorsolateral views of the petrosals UFRJ-DG 1035-M (A) and 347-M (B). Abbreviations: cev s?, sulcus for capsuloparietal emissary vein?; circ. fs, (vascular?) circular fossa; ptn, post-temporal notch; pts, post-temporal sulcus; rsup f, foramen for the ramus superior of stapedial artery; sqs, squamosal articulation surface of petrosal; vdms?, possible sulcus for the vena diploëtica magna.

Figure 11 in A new dentition-based phylogeny of Litopterna (Mammalia: Placentalia) and 'archaic' South American ungulates

Figure 11. Bayesian phylogenies of Litopterna from the undated analyses. A, Hypothesis (H1). B, Hypothesis 2 (H2). H1 and H2 are different hypotheses for the paraconid of notoungulates (see main text). In (A) and (B), node support is indicated using Bayesian posterior probabilities. Litopterna is indicated with a star, but other nodes or tips of relevance are indicated in circles of different colours: blue, orders; black, families. Note that in the Discussion, we redefined the families Anisolambdidae and Sparnotheriodontidae as the subfamilies Anisolambdinae and Sparnotheriodontinae of the family Anisolambdidae. Abbreviations: Ad, Adianthidae; An, Anisolambdidae; As, Astrapotheria; I, Indaleciidae; K, Kollpaniinae; L, Litopterna; Ma, Macraucheniidae; Np, Notopterna; Nt, Notonychopidae; Nu, Notoungulata; Pe, Proterotheriidae; Py, Pyrotheria; S, Sparnotheriodontidae.

Figure 8 in A new dentition-based phylogeny of Litopterna (Mammalia: Placentalia) and 'archaic' South American ungulates

Figure 8. Right upper molars of South American 'condylarths' and 'didolodontids'. A, P4–M3 of Molinodus suarezi in occlusal view [cast of MHNC 1247, P4–M2; cast of MNHN 13870, M3 (mirrored)]. B, roots of M1, M2–M3 of Escribania chubutensis in occlusal view (MLP 90–II-12–68, roots of M1 and M2 (mirrored); MLP 90–II-12–63, M3). C–D, M2 of Raulvaccia peligrensis [MLP 90-II-12- 70 (mirrored)] in occlusal (C) and distoocclusal (D) views. E, P4–M3 of Ricardocifellia protocenica in occlusal view [cast of DNPM 908M, P5–M3 (mirrored); cast of MNRJ 1461-V (mirrored)]. F, M2 of Lamegoia conodonta Paula Couto, 1952 in occlusal view (cast of MNRJ 1465-V). G, P1–M3 of Didolodus multicuspis in occlusal view [MACN 10690, P2–M3 (holotype; mirrored); MACN A 10738, P1]. H, P5–M3 of Protolipterna ellipsodontoides in occlusal view [DNPM LE 444I (mirrored)]. I, P4–M3 of Asmithwoodwardia scotti in occlusal view [DGM 358M (holotype; mirrored)]. J, P2, alveoli of P4–P5, and M1–M3 of Miguelsoria parayiruhnor in occlusal view [MNRJ 4094V (mirrored)]. More information on the specimens and observations are in Supporting information, File S2. Note that the M2 of Molinodus suarezi (A) and the M2 of Lamegoia conodonta (B) present a duplication of their protocone (pr1 and pr2); in the former, this is insipient, and in the latter, it forms a pseudohypocone. For information about the tooth position convention, check the Material and methods. Abbreviations: hy, hypocone; hys, hypostyle; me, metacone; ms, mesostyle; mtl, metaconule; pa, paracone; phy, pseudohypocone; phyc, prehypocrista; pshyc, posthypocrista; pmlc, premetaconular crista; pplc, preparaconular crista; pr, protocone; prl, paraconule; ps, parastyle; pscg, postcingulum; psmlc, postmetaconular crista. Scale bars equal 1 cm.

Figure 7 in A new dentition-based phylogeny of Litopterna (Mammalia: Placentalia) and 'archaic' South American ungulates

Figure 7. Right lower molars of relevant SANUs in occlusal view. A, p1–m3 of the indaleciid Indalecia grandensis [PVL 4186 (p1–p2 mirrored)]. B, p2–m3 of the notonychopid Notonychops powelli [PVL 4298 (mirrored)]. C, p1–m3 of the notoungulate Simpsonotus praecursor [MLP 73-VII-3-11 (holotype; mirrored)]. D, p1–m3 of the astrapothere Trigonostylops wortmani [MNHN.F.CAS188 (mirrored)]. E, p2– m3 of the xenungulate Etayoa bacatensis [cast of GM 32 (holotype; mirrored)]. F, p1–m3 of Eoastrapostylops riolorense [PVL 4216, p1–m2 (holotype; p1–p5, m2 mirrored); PVL 4216, m3. G, p4–m3 of Propyrotherium saxeum [LIEB-PV 3200 (mirrored)]. Relevant anatomical features of the dentition are labelled. More information on the specimens and observations are in Supporting information, File S2. The asterisk is labelling either a paracristid in H1 or a very reduced paraconid in H2 in Simpsonotus praecursor, the tested hypotheses in our analyses. The question mark (?) next to the paraconid of Simpsonotus praecursor is to reflect that in the H1 matrix, this cusp was scored as a paraconid, whereas in the H2 matrix it was scored as a twinned metaconid. For information about the tooth position convention, check the Material and methods. Abbreviations: end, entoconid; hlph, hypolophid; hyd, hypoconid; hyld, hypoconulid; med, metaconid; pad, paraconid; prd, protoconid; pscd, postcristid (or postentocristid). Scale bars equal 1 cm.

Figure 6 in A new dentition-based phylogeny of Litopterna (Mammalia: Placentalia) and 'archaic' South American ungulates

Figure 6. Right upper molars of relevant SANUs. A, P1–M3 of the indaleciid Indalecia grandensis in occlusal view [PVL 4186 (mirrored)]. B, crownless P1, and P2–M3 of the notonychopid Notonychops powelli in occlusal view [PVL 4298 (M1–M3 mirrored)]. C, crownless and broken M2, broken M1, and P5–P2 of the notonychopid Requisia vidmari in occlusal view (UNPSJB PV 944, crownless and broken M2, broken parastyle of M1, and P4–P5 (holotype); UNPSJB PV 947, broken M1; UNPSJB PV 945, P2). D, P1–M3 of Eoastrapostylops riolorense in occlusal view [PVL 4216 (holotype)]. E, P1–M3 of the notoungulate Simpsonotus praecursor in occlusal view [MLP 73-VII-3-11 (holotype; mirrored)]. F–G, unworn M1 or M2 of the notoungulate Henricosbornia sp. (MACN A 10717) in occlusal (F) and distoocclusal (G) views. H, P2–M3 of the astrapothere Trigonostylops wortmani (AMNH VP-28700). I, P5–M3 of the xenungulate Carodnia vieirai [cast of DGM 335M, P5–M2 (mirrored); cast of AMNH VP-49828, M3 (mirrored)]. J, P5–M3 of Propyrotherium saxeum [AMNH unnumbered (labelled as 'O3')], right M3 (there is a mesiobuccal portion missing); MLP 55-III-10-1a, right M1 or M2 (duplicated for illustrating M1–M2); MACN A 10929 (lectotype), left P5 (lectotype; mirrored). Relevant anatomical features of the dentition are labelled. More information on the specimens and observations are in Supporting information, File S2. The asterisks mark the hypocone and prehypocrista in notoungulates, as they could potentially not be homologous with the hypocone and prehypocrista in other SANUs, considering a different origin of the hypocone in notoungulates (see more in the Material and methods and in Supporting information, File S2). For information about the tooth position convention, check the Material and methods. Abbreviations: efx, ectoflexus; hy, hypocone; me, metacone; ms, mesostyle; mtl, metaconule; pa, paracone; pcg, precingulum; phyc, prehypocrista; pmlc, premetaconular crista (or crochet in notoungulates); pplc, preparaconular crista; pr, protocone; prl, paraconule; prt, protostyle; ps, parastyle; pscg, postcingulum; psmlc, postmetaconular crista; psprc, postprotocrista. Scale bars equal 1 cm.

Figure 5 in A new dentition-based phylogeny of Litopterna (Mammalia: Placentalia) and 'archaic' South American ungulates

Figure 5. Right lower molars of Litopterna in occlusal view. A, p1–p4 of Polymorphis lechei [holotype; MLP 12-2168 (mirrored)]. B, p1–m3 of Cramauchenia normalis [MNHN.F.COL181 (mirrored)]. C, m3 of Cramauchenia normalis (AMNH-VP 29753). D, p1–m3 of Theosodon lydekkeri [MACN A 24-90 (mirrored)]. E, m2–m3 of Proectocion sp. (MLP 59-II-28-107). F, p5–m3 of Tricoelodus bicuspidatus (MACN A 52-203, p5–m2 (holotype); cast of FMNH P14696, m3). G, p2–m3 of Proadiantus excavatus (MACN A 52-214). H, p1, dp2–dp5 and m1–m3 of Lambdaconus suinus (MACN A-52-199, p1, dp2–dp5 and m1–m2; MNHN.F.DES159, m3). I, p1–m3 of Diadiaphorus majusculus (MACN A 9180-82, p2–m3; YPM PU 15799, p1). J, m1–m3 of Anisolambda fissidens (MACN A 10668; holotype). K, m2–m3 of Paranisolambda prodromus (cast of MNRJ 1496V, m2 (mirrored); cast of MNRJ 1859V, m3 (mirrored). L, m2 of Victorlemoinea prototypica (MNRJ 1482V). M, p1–m3 of Sparnotheriodon epsilonoides (MACN 18225; holotype). N, O, m3 of Wainka tshotshe? [AMNH VP-29101 (mirrored)]. Relevant anatomical features of the dentition are labelled. More information on the specimens and observations are in Supporting information, File S2. For information about the tooth position convention, check the Material and methods. Abbreviations: end, entoconid; hlph, hypolophid; hyd, hypoconid; hyld, hypoconulid; med, metaconid; mlph, mesolophid; pad, paraconid; prd, protoconid; prgd, precingulid; psmcd, postmetacristid. Scale bars equal 1 cm.

Figure 3 in A new dentition-based phylogeny of Litopterna (Mammalia: Placentalia) and 'archaic' South American ungulates

Figure 3. Dental nomenclature used in the text and the characters. A, right upper molar in occlusal view. B–D, right lower molars in occlusal view. The main cusps of the molars are highlighted in bold. The molars represent structures sometimes present in SANUs and with relevance in the character scoring of this study. The molars do not represent any particular SANU. Molars in A and B were partially based on drawings from Gelfo (2006). Abbreviations upper molar: ecg, buccal cingulum or ectocingulum; es, entostyle; hy, hypocone; hys, hypostyle; me, metacone; ms, mesostyle; mt, metastyle; mtl, metaconule; pa, paracone; pcg, precingulum; phyc, prehypocrista; pmc, premetacrista; pmlc, premetaconular crista; ppc, preparacrista (or paracrista); pplc, preparaconular crista; pprc, preprotocrista; pr, protocone; prl, paraconule; prt, protostyle; ps, parastyle; pscg, postcingulum; pshyc, posthypocrista; psmc, postmetacrista (or metacrista); psmlc, postmetaconular crista; pspc, postparacrista; psplc, postparaconular crista; psprc, postprotocrista. Abbreviations lower molar: co, cristid obliqua; encd, entocristid; end, entoconid; dbgd, distobuccal cingulid; dlgd, distolingual cingulid; hlph, hypolophid; hycd, hypocristid; hyd, hypoconid; hyld, hypoconulid; mbgd, mesiobuccal cingulid; med, metaconid; mlgd, mesiolingual cingulid; mlph, mesolophid; msd, mesoconid; pacd, paracristid; pad, paraconid; peld, preentoconulid; pmcd, premetacristid; prcd, protocristid; prd, protoconid; prgd, precingulid; pscd, postcristid (or postentocristid); pseld, postentoconulid; psgd, postcingulid; psmcd, postmetacristid.

Figure 4 in A new dentition-based phylogeny of Litopterna (Mammalia: Placentalia) and 'archaic' South American ungulates

Figure 4. Right upper molars of Litopterna in occlusal view. A, M3 of Polymorphis ligatus (holotype, MLP 12-2169). B, M3 of Polymorphis? (AMNH-VP 29481). C, M2? of Polyacrodon lanciformis Roth, 1899 [MLP 12-2170 (mirrored)]. D, P1–M3 of Cramauchenia normalis (MLP 85-VII-3-38a). E, P1–M3 of Theosodon garretorum (FMNH P 13175). F, P5–M3 of Proectocion precisus (holotype; MACN A 10679). G, P2– M3 of Tricoelodus bicuspidatus [cast of MLP 61-IV-11-65 (P2–P4 mirrored)]. H, M3 of Proectocion argentinus (holotype; MACN A 10673). I, M1 of Lambdaconus suinus [MNHN.F.DES162 (mirrored)]. J, P1–M3 of Diadiaphorus majusculus (MLP 12-304). K, P4–M3 of Lambdaconus suinus (MACN A 52-198; P4 was mirrored). L, M1–M3 of Victorlemoinea prototypica (AMNH-VP 111963, M1 (cast of MNRJ specimen); cast of MNRJ 1470V, M2 (holotype; mirrored); cast of MNRJ 1472V, M3 (mirrored). M, M1–M3 of Paranisolambda prodromus (cast of DGM 304M, M1; cast of DGM 310M, M2–M3). N, P4–M3 of Anisolambda sp. (MLP 59-II-28-68, P4-P5 (mirrored); MLP 59-II-24-453, M1; MNHN.F.CAS 486, M2 (mirrored); MNHN.F.CAS488, M3 (mirrored). O, P5? of Wainka tshotshe (holotype; AMNH VP-28505 (mirrored). Relevant anatomical features of the dentition are labelled. Taxa with two prehypocristae are numbered from buccal (phyc1) to lingual (phyc2). When there are two cristae originating from the same cusp, they are numbered. More information on the specimens and observations are in Supporting information, File S2. For information about the tooth position convention, check the Material and methods. Abbreviations: hy, hypocone; hys, hypostyle; me, metacone; ms, mesostyle; mtl, metaconule; pa, paracone; phyc, prehypocrista; pmc, premetacrista; pmlc, premetaconular crista; pplc, preparaconular crista; pr, protocone; prl, paraconule; prt, protostyle; psmlc, postmetaconular crista; psplc, postparaconular crista; psprc, postprotocrista. Scale bars equal 1 cm.

Figure 2 in A new dentition-based phylogeny of Litopterna (Mammalia: Placentalia) and 'archaic' South American ungulates

Figure 2. Diversity of litoptern and associated early SANU families expressed as the number of genera. A, pie chart expressing the relative diversity of each family. B, diversity over time of the different families of interest with colours corresponding to the families listed in (A). C, same as (B) but using a smoothing function that averages the different occurrences aiding the eye in seeing patterns. In (A) the number of genera for each family is indicated next to the name between brackets. In (C) the function geom_smooth from the R package ggplot v.3.4, method = loess and span = 0.5 was used. In (B) and (C) apart from the standard Periods, Epochs, and Ages below, the SALMAs are indicated in grey boxes crossing the plots. The Tiupampan and Peligran SALMAs and the Bonaerian and Lujanian SALMAs are taken as only two temporal units instead of four for the plots. The data on taxa and occurrences were taken from Supporting information, Table S1, and the temporal information on SALMAs were taken from Supporting information, File S6. Note that the two genera of 'amilnedwarsids' were not included in this plot. Note that in the Discussion section, we proposed to redefine the families Anisolambdidae and Sparnotheriodontidae as the subfamilies Anisolambdinae and Sparnotheriodontinae of the family Anisolambdidae. Abbreviations: Ba, Barrancan; Bo/Lu, Bonaerian and Lujanian; Cc, Colloncuran; Cd, Carodnia Zone; Ch, Chasicoan; Co, Colhuehuapian; Cp, Chapadmalalan; De, Deseadean; En, Ensenadan; Hu, Huayquerian; It, Itaboraian; La, Laventan; Ma, Marplatan; Mo, Montehermosan; Mu, Mustersan; Ri, Riochican; Sa, Sapoan; San, Santacrucian; Tg, Tinguirirican; Ti/Pe, Tiupampan and Peligran; Va, Vacan.

Figure 1 in A new dentition-based phylogeny of Litopterna (Mammalia: Placentalia) and 'archaic' South American ungulates

Figure 1. Phylogenies of the order Litopterna illustrating its interordinal relationships (A–B) and its interfamilial relationships (C–D). A, Buckley (2015) phylogeny. B, Westbury et al. (2017) phylogeny. C, Cifelli (1993) phylogeny. D, Bonaparte and Morales (1997) phylogeny. Different colours in the branches indicate different families or orders: blue Adianthidae; brown, Notopterna; green, Proterotheriidae; red, Macraucheniidae; yellow, Sparnotheriodontidae. Litopterna is indicated with a star, but other nodes or tips of relevance are indicated in circles: blue, orders; orange, suborders; pink, superfamilies; black, families; green, non-defined rank. Abbreviations: Ad, Adianthidae; An, Anisolambdidae; Di, Didolodontidae; I, Indaleciidae; L, Litopterna; Lo, Lopholipterna; Ma, Macraucheniidae; Mo, Macrauchenoidea; Nu, Notoungulata; Pa, Panperissodactyla; Pe, Proterotheriidae; Po, Protolipternidae; S, Sparnotheriodontidae.

Figure 12. Tip-dated Bayesian phylogenetic analyses. A, unconstrained phylogeny using hypothesis 1 in A new dentition-based phylogeny of Litopterna (Mammalia: Placentalia) and 'archaic' South American ungulates

Figure 12. Tip-dated Bayesian phylogenetic analyses. A, unconstrained phylogeny using hypothesis 1 (H1) matrix. B, tip-dated topology constrained Bayesian phylogeny using hypothesis 1 (H1) matrix and constraining the node for the common ancestor of SANUs between the K/Pg boundary and the oldest age for the kollpaniines of Tiumpampa (66–65.075 Mya). The topological constraint in (B) was based on the topology of the undated Bayesian tree for H1. The trees in (A) and (B) represent a 50% majority rule in which tree support is indicated using Bayesian posterior probabilities in the nodes, and the node bars represent the 95% highest posterior density (HPD) for the estimated node ages. In (B), node support is only indicated for the node that was unconstrained (the undated tree presented a polytomy for that node). Litopterna is indicated with a star, but other nodes or tips of relevance are indicated in circles of different colours: blue, orders; black, families.

Figure 9 in A new dentition-based phylogeny of Litopterna (Mammalia: Placentalia) and 'archaic' South American ungulates

Figure 9. Right lower molars of South American 'condylarths' and 'didolodontids' in occlusal view. A, p4–m3 of Molinodus suarezi [cast of MHNC 13867 (mirrored)]. B, m2–m3 of Escribania chubutensis [UNPSJB PV 916 (holotype; mirrored)]. C, talonid of m2, and m3 of Raulvaccia peligrensis [MLP 90−II−12−69 (mirrored)]. D, P5–M3 of Ricardocifellia protocenica [MNRJ 1431-V, m1–m3 (mirrored); MNRJ 1450-V, p5 (mirrored)]. E, p2–m3 of Didolodus multicuspis (MACN A 10689). F, p2–m3 of Protolipterna ellipsodontoides [cast of DGM 1308M (mirrored)]. G, p1–m3 of Asmithwoodwardia scotti (cast of DGM 358M (holotype; mirrored)]. H, p4–m3 of Miguelsoria parayiruhnor (cast

Figure 10 in A new dentition-based phylogeny of Litopterna (Mammalia: Placentalia) and 'archaic' South American ungulates

Figure 10. Most parsimonious trees (MPTs) from the maximum parsimony analyses. A, Hypothesis 1 (H1). B, Hypothesis 2 (H2). H1 and H2 are different hypotheses for the paraconid of notoungulates (see main text). The numbers next to each node of the tree are the absolute Bremer supports on the left side and the Jackknife resampling support values on the right side. Litopterna is indicated with a star, but other nodes or tips of relevance are indicated in circles of different colours: blue, orders; black, families. Note that in the Discussion section, we redefined the families Anisolambdidae and Sparnotheriodontidae as the subfamilies Anisolambdinae and Sparnotheriodontinae of the family Anisolambdidae. Abbreviations: Ad, Adianthidae; An, Anisolambdidae; As, Astrapotheria; I, Indaleciidae; L, Litopterna; Ma, Macraucheniidae; Np, Notopterna; Nt, Notonychopidae; Nu, Notoungulata; Pe, Proterotheriidae; Py, Pyrotheria; S, Sparnotheriodontidae; X, Xenungulata.