The first Jurassic mammal from South America
O. W. M. Rauhut, T. Martin, E. Ortiz-Jaureguizar & P. Puerta
Supplementary information
Phylogenetic analysis:
To test the phylogenetic position of Asfaltomylos patagonicus, we inserted this taxon into the data matrices made available by Luo et al. (2001) in the supplementary data of that paper. Luo et al. analyzed three matrices: a primary with 21 taxa and 55 dental and mandibular characters, a first extended matrix, containing 21 taxa and 125 characters of all regions of the skeleton, and a second extended matrix with 26 taxa and 125 characters from all regions of the skeleton. Although we inserted Asfaltomylos, for which only the 55 dental and mandibular characters could be coded (see below), in all three matrices, only the result for the second extended, most inclusive matrix is shown in the paper (Fig. 3). The matrices were analyzed using PAUP 3.1.1 (Swofford 1992), with the heuristic branch-and-bound search, set at random with 100 replicates. Characters were treated as outlined by Luo et al. (2001), with the multistate characters 6 and 21 being treated as ordered.
The result of all three analyses was essentially the same: the inclusion of Asfaltomylos drastically reduced the number of equally parsimonious trees, helped to resolve the polytomy within Australosphenida, and placed Asfaltomylos as the most basal member of this group.
The tree statistics are as follows: the primary analysis resulted in the recovery of 10 most parsimonious trees of a length of 169 steps (CI: 0.467, RI: 0.725, RC: 0.339). The first extended analysis resulted in 4 most parsimonious trees of a length of 258 steps (CI: 0.616, RI: 0.796, RC: 0.490). The second extended analysis retrieved 4 most parsimonious trees of a length of 327 steps (CI: 0.508, RI: 0.751, RC: 0.381).
To evaluate the support of australosphenidan monophyly by the available character data, both a bootstrap analysis was executed (1000 replicates) and the Bremer support was calculated for the second extended analysis. Although bootstrap support values were low (54%), the Bremer support indicates that the Australosphenida are one of the best supported clades in the analysis. Five additional steps are needed to collaps the Australosphenida; at that length, the only stable node in the cladogram is Mammalia. The boreosphenidan clade collapses at three additional steps.
Character codings for Asfaltomylos:
Only the first 55 of the total of 125 characters given by Luo et al. (2001) could be coded for Asfaltomylos:
1-5 6-10 11-15 16-20 21-25 26-30 31-35 36-40 41-45 46-50
0?1?? 20000 11??0 10?1? 3131? 10110 11000 01120 411?2 ?1111
51-55
1?010
Character state changes in Australosphenida:
Character state changes on the lineage leading towards monotremes in the second extended analysis were traced using the tree description option of PAUP 3.1.1 (Swoffort 1992) and the character trace option of MacClade 3 (Maddison & Maddison 1992). Since the inclusion of Asfaltomylos did not affect tree shape on the lineage leading towards Boreosphenida, character state changes for this lineage are not listed here; we refer to Luo et al.’s supplementary data for information about state changes in this lineage. Characters were traced on a strict consensus tree of the four most parsimonious trees created by STRICT (Thorley & Wilkinson 1997), using both ACCTRAN and DELTRAN optimizations. In addition to the character state changes, bootstrap and Bremer support values are given at each node.
/---------------------- Shuotherium
|
----1 /------------------ Asfaltomylos
| |
\---2 /--------------- Ambondro
| |
\--3 /----------- Ausktribosphenos
| |
\---4 /------- Steropodon
| |
\---5 /---- Obdurodon
\--6
\---- Ornithorhynchus
Node 1: Shuotherium + Australosphenida
Bootstrap: 46,8 %; Bremer: +1
Unambiguous character state changes:
Character 18 (0->1): Labial cingulid present in ultimate lower premolar. Convergently present in Gobiconodon.
Character 19 (0->1): Lingual cingulid present in ultimate lower premolar.
Character 21 (0 or 1 ->2): Primary cusps in lower molars arranged in a reversed triangle with weakly developed postvallum/prevallid shearing. Also present in Kuehneotherium, Henkelotherium, Vincelestes, Peramus, and Kielantherium.
Additional changes under DELTRAN:
Character 13 (0->1): Main cusp a of ultimate lower premolar symmetrical. Also present in Sinoconodon, Gobiconodon, Zhangheotherium, Vincelestes, and placentals.
Character 36 (2->0): Interlocking mechanism between two adjacent lower molars absent. Reversal to the ancestral, non-mammalian condition. Also found in multituberculates, Zhangheotherium, Vincelestes, and Henkelotherium. Reversed in Ambondro.
Character 47 (0->1): Wear facets matches upon the eruption of teeth. Also present in the clade containing all descendents of the last common ancestor of multituberculates and placentals.
Character 125 (1->2): Occlusion unilateral, with strong rotation. Also present in Zhangheotherium, Henkelotherium, Peramus, Vincelestes, Kielantherium, Erinaceus, Prokennalestes, and Didelphis. Reversed in Obdurodon and Ornithorhynchus.
Additional changes under ACCTRAN:
Character 23 (2->3): Wear facets between the upper an lower molar cusps present, the talonid occluding with the lingual face of the upper molar. Unknown in Shuotherium. Convergently present in Cladotheria.
Character 26 (0->1): Crista obliqua pointed between the metaconid-protoconid notch and the protoconid. Non-applicable in Shuotherium (and the vast majority of basal mammals). Reversed in monotremes.
Character 33 (0->2): Mesial transverse cingulum above the gum present below the trigonid and continuous. Not present in Asfaltomylos, which is interpreted as a reversal by ACCTRAN.
Character 39 (0->2): Talonid is equal or wider than trigonid in m2. Not applicable in Shuotherium and convergently present in Erinaceus and Didelphis.
Character 45 (0->2): Talonid at the cingulid level wider than long. Not applicable in Shuotherium (and all other basal mammals). Transformed in Ambondro.
Character 52 (0->1): Facet 4 (on the posterior aspect of the hypoconid) present and transverse. Not applicable in Shuotherium and Ornithorhynchus (and all basal mammals), unknown in Asfaltomylos, and convergently present in Erinaceus.
Character 54 (0->1): Wear pattern within the talonid basin present. Not applicable in Shuotherium and all basal mammals. Convergently present in boreosphenidans and reversed in monotremes.
Character 58 (0->1): Atlas neural arch and intercentrum fused in adults. Only known in Ornithorhynchus and convergently present in therians.
Character 61 (0->1): Postaxial cervical ribs absent in adults. Only known in Ornithorhynchus. Convergently present in Vincelestes and therians.
Character 62 (0->1): 15 or more thoracic vertebrae. Only known for Ornithorhynchus and convergently present in Jeholodens.
Character 69 (1->0): Supraspinous fossa on scapula absent. Only known in Ornithorhynchus. This is a reversion of a mammaliform synapomorphy.
Character 87 (0->1): Acetabular dorsal emargination closed. Only known in Ornithorhynchus. Convergently present in Zhangheotherium and therians.
Character 88 (0->1): Sutures of the ilium, ischium, and pubis within the acetabulum fused in adults. Only known in Ornithorhynchus. Convergently present in multituberculates, Vincelestes and therians.
Character 106 (0->1): Unpaired sesamoid bones present in flexor tendons. Only known in Ornithorhynchus.
Character 112 (0->1): Cochlea elongate and partly coiled. Only known in Ornithorhynchus and convergently present in Vincelestes.
Node 2: Australosphenida
Bootstrap: 54.4 %; Bremer: +5
Unambiguous character state changes:
Character 21 (2->3): Primary cusps on lower molars arranged in a reversed triangle with strongly developed postvallum/prevallid shearing. Convergently present in Zhangheotherium and therians.
Character 22 (0->1): Less than 4 molars. Convergently present in Trioracodon, multituberculates, Vincelestes, and placentals.
Character 24 (0->1): Posterior cusp c and primary cusp a are equal or subequal in height in anterior lower molars. Convergently present in Trioracodon, Henkelotherium, and marsupials.
Character 41 (1->4): Talonid developed as a broad basin, rimmed with 3 functional cusps. Convergently present in boreosphenidans and transformed in monotremes.
Character 42 (0->1): Hypoconulid present, posterior and median. Convergently present in Henkelotherium, Peramus, Kielantherium, and placentals.
Character 51 (0->1): Wear facet 3 and 4 differentiated. Convergently present in Zatheria.
Additional changes under DELTRAN:
Character 11 (0->1): Ventral ridge of masseteric fossa present as a well defined thin crest. Not present in Shuotherium, thus interpreted as a convergent development between Australosphenidans and the clade containing ”eutriconodonts”, modern therians and all descendants of their last recent common ancestor. Under ACCTRAN, this character is interpreted as a mammalian synapomorphy that is reversed in Shuotherium.
Character 12 (0->1): Dentary condyle positioned above the level of the postcanine alveoli. Unknown in Shuotherium. Under ACCTRAN, this character is interpreted as a mammalian synapomorphy that is reversed in ”eutriconodonts”.
Character 23 (2->3): Wear facets between upper and lower molar cusps present, the talonid occluding with the lingual face of the upper molar. See under ACCTRAN at Node 1.
Character 26 (0->1): Cristid obliqua pointed between the metaconid-protoconid notch and the protoconid. See under ACCTRAN at Node 1.
Character 39 (0->2): Talonid is equal or wider than trigonid in m2. See under ACCTRAN at Node 1.
Character 45 (0->2): Talonid at cingulid level wider than long. See under ACCTRAN at Node 1.
Character 54 (0->1): Wear pattern within talonid basin present. See under ACCTRAN at Node 1.
Additional character state changes under ACCTRAN:
Character 44 (0->1): Entoconid present. Unknown in Asfaltomylos, reversed in monotremes, and convergently present in therians.
Node 3: Ambondro, Ausktribosphenos + Monotremata
Bootstrap: 55.4 %; Bremer: +3
Unambiguous character state changes:
Character 15 (0->1): Principal cusp a, cusp b and cusp c of ultimate lower premolar arranged triangular. Convergently present in Erinaceus.
Character 16 (1->2): Presence of a continuous posterior cingulid in the ultimate lower premolar.
Character 17 (0->1): Ultimate lower premolar transversely wide. Convergently present in Erinaceus.
Character 34 (0->1): Presence of a shelf-like mesial cingulid wrapping around the anterointernal corner of the molar to extend to the lingual side of the trigonid below the paraconid.
Character 40 (0->2): Ectoflexid very deep (equal or more than 60% of the width of the talonid).
Additional character state changes under DELTRAN:
Character 33 (0->2): Presence of a continuous mesial transverse cingulum above the gum. See under ACCTRAN at Node 1.
Character 52 (0->1): Facet 4 present and transverse. See under ACCTRAN at Node 1.
Node 4: Ausktribosphenos + Monotremata
Bootstrap: 48.1 %; Bremer: +2
Unambiguous character state changes:
Character 38 (1->2): Paraconid lingually positioned and trigonid cusps forming an acute angle.
Character 49 (1->2): Prevallum/postvallid shearing hypertrophied and transverse. Convergently present on Zhangheotherium and boreosphenidans.
Character 53 (0->1): Posterolateral aspect of the talonid angular. Convergently present in Erinaceus.
Node 5: Monotremata
Bootstrap: 76.3 %; Bremer: +4
Unambiguous character state changes:
Character 26 (1->0): Cristid obliqua pointed between the metaconid-protoconid notch and the metaconid. This is a reversal of a possible australosphenidan synapomorphy (under DELTRAN). The same character state is present in zatherians.
Character 30 (1->0): Posterior lingual cingulid of the lower molar absent or weak. This is a reversal of a holotherian synapomorphy. The same reversal is present in Asfaltomylos, Jeholodens, multituberculates, and cladotherians.
Character 41 (4->3): Talonid developed as a transverse V-shaped basin with two functional cusps. This is a modification of an australosphenidan synapomorphy.
Character 54 (1->0): Wear pattern within the talonid basin absent. This is a reversal of a possible australosphenidan synapomorphy.
Additional character state changes under ACCTRAN:
Character 2 (0->1): Separate scars for surangular/prearticular in the meckelian groove and the post-dentary trough absent. Unknown in Steropodon and convergently present in the clade constituing all descendants of the most recent common ancestor of ”eutriconodonts” and therians.
Character 4 (1->0): Meckelian groove curved and parallel to the ventral border of the mandible. This character is only known in Steropodon. It is a reversal of a mammaliform synapomorphy, which is also present in the clade constituing all descendants of the most recent common ancestor of ”eutriconodonts” and therians, with the exception of Peramus.
Character 7 (0->1): Coronoid absent. Unknown in Steropodon and convergently present in Trioracodon and therians.
Character 8 (0->1): Mandibular foramen not associated with either postdentary trough or the meckelian groove. Unknown in Steropodon and convergently present in the clade constituing all descendants of the most recent common ancestor of ”eutriconodonts” and therians.
Character 9 (0->1): Pterygoid fossa present on the medial side of the mandible. Unknown in Steropodon and convergently present in the clade constituing all descendants of the most recent common ancestor of ”eutriconodonts” and therians.
Character 10 (0->1): Medial pterygoid ridge along the ventral border of the coronoid part of the mandible present. Unknown in Steropodon and convergently present in the clade constituing all descendants of the most recent common ancestor of ”eutriconodonts” and therians.
Character 44 (1->0): Entoconid absent. This is a reversal of a possible australosphenidan synapomorphy. Lack of the entoconoid is shared with all mammaliforms with the exception of Ambondro, Ausktribosphenos, and therians (the character state is unknown in Asfaltomylos).
Character 125 (2->1): Occlusion unilateral, with mobile symphysis. Unknown in Steropodon. This is a reversal of a possible mammalian synapomorphy. Within Mammalia, the character state is also present in ”eutriconodonts”, Vincelestes, Didelphis, and Asioryctes.
Node 6: Ornithorhynchidae
Bootstrap: 69.1 %; Bremer: +2
Unambiguous character state changes:
Character 1 (0->1): Postdentary trough absent. Convergently present in the clade constituing all descendants of the most recent common ancestor of ”eutriconodonts” and therians.
Character 56 (1->2): Multiple postcanine roots.
Additional character state changes under DELTRAN:
Character 2 (0->1): Seperate scars for surangular/prearticular in the meckelian groove and the post-dentary trough absent. See under ACCTRAN at Node 5.
Character 7 (0->1): Coronoid absent. See under ACCTRAN at Node 5.
Character 8 (0->1): Mandibular foramen not associated with either postdentary trough or the meckelian groove. See under ACCTRAN at Node 5.
Character 9 (0->1): Pterygoid fossa present on the medial side of the mandible. See under ACCTRAN at Node 5.
Character 10 (0->1): Medial pterygoid ridge along the ventral border of the coronoid part of the mandible present. See under ACCTRAN at Node 5.
References:
Luo, Z.-X., R. L. Cifelli & Kielan-Jaworowska, Z. 2001. Dual origin of tribosphenic mammals. Nature 409:53-57.
Maddison, W. P. & Maddison, D. R. 1992. MacClade: Analysis of phylogeny and character evolution. Version 3. Sunderland: Sinauer Associates.
Swofford, D. L. 1992. PAUP: Phylogenetic analysis using parsimony, version 3.1. Champaign: Illinois Natural History Survey.
Thorley, J. & Wilkinson, M. 1997. Strict: Computes strict reduced cladistic consensus profiles. Bristol: University of Bristol.
9