The origin of the internal nostril of tetrapods
Min Zhu* & Per E. Ahlberg†
*Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, P. O. Box 643, Beijing 100044, China
†Department of Evolutionary Organismal Biology, Evolutionary Biology Centre, Uppsala University, Norbyvägen 18A, SE-752 36 Uppsala, Sweden
Supplementary Methods
I, Phylogenetic analysis. We performed the analysis using the software package PAUP3.1
with the data matrix of ref. 11 which scored 29 taxa for 99 morphological
characters. Based on additional materials or new examination, Kenichthys was complemented
with 31 additional morphological characters coded (in bold below). Character 39 is re-coded for 9 genera. We used the same algorithms as in ref. 11, i.e. most parsimonious trees were
identified using the heuristic search algorithm, stepwise addition, with 500 random iterations. All characters were weighted equally. Characters 15, 20, 25, 32 and 80 were ordered, and all other characters were unordered. Note that Characters 23 and 70 (ordered in ref. 11, of two-state in the data matrix) were unordered. The analysis yielded 18 most parsimonious trees showing the same major groupings (except the resolution of three megalichthyids) as ref. 11. For the purpose of the comparison, we also performed the analysis with all characters unordered, that yielded 12 most parsimonious trees. Two consensus trees only differed in the resolution of Youngolepis as the sister group of Diabolepis + Dipterus. Kenichthys always
appeared as the most basal tetrapodomorph.
II, Character list of ref. 11 with new codings for Kenichthys in bold. Characters 7 and 98
are redefined (in italics).
1 Parasymphysial plate: 0 - long, sutured to coronoid, denticulated or with tooth row; 1 - short, not sutured to coronid, denticulated; 2 - carrying tooth whorl (unordered). 2 Splenial: 0 - not sutured to prearticular; 1 - sutured to prearticular.
3 Anterior end of prearticular: 0 - not forked; 1 - forked.
4 Prearticular and angular: 0 - separated by ventral exposure of Meckelian bone; 1 - in contact.
5 Prearticular: 0 - rear part with conspicuous horizontal ledge; 1 - rear part flat. 6 Retroarticular process: 0 - absent; 1 - present.
7 Parasymphysial plate: detachable whorl (0); sutured plate with denticles or teeth (1).
8 Coronoid proportions: 0 - posterior coronoid same length as middle coronoid, or shorter; 1 - posterior coronoid significantly longer than middle coronoid. 9 Marginal denticle band on coronoids: 0 - narrower than fang-bearing lamina; 1 - broader than fang-bearing area, at least posteriorly.
10 Length of dentary; 0 - long; 1 - short with lip fold.
11 Dentary tooth row reaches symphysis: 0 - yes; 1 - no.
12 Dentary fang pair: 0 - absent; 1 - present.
13 Number of fang pairs on posteriormost coronoid: 0 - one; 1 - two; 2 - none (unordered).
14 Tooth folding: 0 - none; 1 - generalized polyplocodont; 2 - labyrinthodont; 3 -
dendrodont (unordered).
15 Infradentary foramina: 0 - always present; 1 - variable; 2 - always absent (ordered). 16 Dentition of palatoquadrate complex; 0 - marginal teeth; 1 - tooth plates. 17 Number of fang pairs on ectopterygoid: 0 - one; 1 - two; 2 - none (unordered).
18 Proportions of entopterygoid: 0 - anterior end level with processus ascendens; 1 - anterior end considerably anterior to processus ascendens.
19 Entopterygoids meeting in midline: 0 - no; 1 - yes.
20 Posterior process of vomers: 0 - absent; 1 - short; 2 - long (ordered).
21 Anteromedial process of vomer: 0 - absent, vomers separated; 1 - present; 2 - absent, vomers in close contact (unordered).
22 Vomer proportions: 0 - not much broader than long; 1 - much broader than long.
23 Relationship of vomer to parasphenoid: 0 - no contact, or simple abutment; 1 -
overlap.
24 Vomerine fangs: 0 - absent; 1 - present.
25 Internasal pits: 0 - undifferentiated; 1 - strong midline ridge but shallow pits; 2 - deep
pear-shaped pits (ordered).
26 Posterior end of parasphenoid: 0 - denticulated field extends into spiracular groove; 1 -
denticulated field does not extend into spiracular groove.
27 Enlarged anterior tooth on premaxilla: 0 - absent; 1 - present.
28 Choana: 0 - absent; 1 - present.
29 External nostrils: 0 - two pairs; 1 - one pair.
30 Position of anterior external nostril: 0 - facial; 1 - edge of mouth. 31 Orientation of anterior tectal and lateral rostral relative to external nostril: 0 -
dorsal/ventral; 1 -posterior/anterior.
32 Width of ethmoid relative to length from snout tip to posterior margin of parietals: 0 - more than 80%; 1 - 70-80%; 20 - 50-70%; 2 - less than 40% (ordered).
33 Extent of crista parotica: 0 - does not reach posterior margin of tabular; 1 - reaches posterior margin of tabular.
34 Cosmine: 0 - present; 1 - absent.
35 Westoll lines: 0 - absent; 1 - present.
36 Pineal foramen: 0 - present; 1 - absent.
37 Location of pineal foramen/eminence: 0 - level with posterior margin of orbits; 1 - well posterior to orbits.
38 Parietals surround pineal foramen/eminence: 0 - yes; 1 - no.
39 Shape of pineal series: 0 - round or oval; 1 - kite-shaped with distinct posterior corner. (non-applicable for Kenichthys)
40 Proportions of postparietal shield: 0 - not extremely wide posteriorly; 1 - extremely wide posteriorly.
41 Postparietals narrow to a point posteriorly: 0 - no; 1 - yes.
42 Posterior margin of tabulars: 0 - anterior to posterior margin of postparietals; 1 - level with posterior margin of postparietals.
43 Median postrostral: 0 - absent (postrostral mosaic); 1 - present; 2 - absent (nasals meet in midline) (unordered).
44 Number of nasals: 0 - many; 1 - one or two.
45 Frontals: 0 - absent; 1 - present.
46 B-bone: 0 - absent; 1 - present.
47 Extratemporal: 0 - present; 1 - absent.
48 Contact between extratemporal and supratemporal: 0 - absent; 1 - present. 49 Supratemporal series: 0 - complete; 1 - tabular only.
50 Postspiracular: 0 - absent; 1 - present.
51 Posterodorsal process of maxilla: 0 - present; 1 - very weak or absent. 52 Jugal-quadratojugal contact: 0 absent; 1 - present.
53 Relationship of jugal to orbit: 0 - contributes to orbital margin; 1 - excluded from
orbital margin.
54 Postorbital bone: 0 - contributes to orbital margin; 1 - excluded from orbital margin.
55 Contact between posterior supraorbital and intertemporal: 0 - present; 1 - absent. 56 Contact between posterior supraorbital and lacrimal: 0 - absent; 1 - present.
57 Contact between parietal and supraorbital: 0 - present; 1 - absent. 58 Shape of posterior supraorbital: 0 - posterior process shorter than orbital margin; 1 - posterior process much longer than orbital margin.
59 Position of orbits: 0 - lateral and widely separated; 1 - dorsal and close together. 60 Preoperculosubmandibular: 0 - absent; 1 - present.
61 Subsquamosals: 0 - absent; 1 - present.
62 Quadratojugal, squamosal and preopercular fused: 0 - no; 1 - yes. 63 Foramina (similar to infradentary foramina) on cheekplate: 0 - absent; 1 - present. 64 Extrascapular bone overlaps: 0 - median overlaps laterals; 1 - laterals overlap median.
65 Anterior margin of median extrascapular: 0 - long; 1 - very short.
66 Postotic sensory canal: 0 - runs through skull roof; 1 - follows edge of skull roof. 67 Postorbital junction of supraorbital and infraorbital canals: 0 - absent; 1 - present. 68 Premaxilla canal-bearing: 0 - yes; 1 - no.
69 Infraorbital canal follows premaxillary suture: 0 - no; 1 - yes. 70 Groups of small pores on skull roof: 0 - absent; 1 - rare. 71 Dermal intracranial joint: 0 - absent; 1 - present.
72 Endoskeletal intracranial joint: 0 - absent; 1 - present.
73 Endoskeletal joint line slopes anteroventrally: 0 - no; 1 - yes.
74 Position of endoskeletal joint: 0 - runs through profundus foramen; 1 - runs through trigeminus foramen.
75 Postorbital pillar 0 - absent; 1 - present.
76 Basicranial fenestra: 0 - absent; 1 - present.
77 Notochordal pit on sphenoid: 0 - absent; 1 - present.
78 Processus descendens of sphenoid: 0 - absent; 1 - present.
79 Pituitary vein exit: 0 -anterior; 1 - dorsal.
80 Posterior carotid opening in parasphenoid: 0 - large; 1 - small; 2 - absent (ordered).
81 Profundus foramen in postnasal wall: 0 - small; 1 large.
82 Rostral tubuli: 0 - absent; 1 - present.
83 Tectum orbitale: 0 -narrow; 1 - extensive.
84 Contact margin for clavicle on cleithrum: 0 - straight or faintly convex; 1 - strongly
concave.
85 Anocleithrum: 0 - exposed; 1 - subdermal.
86 Archipterygial pectoral fin: 0 - no; 1 - yes.
87 Shoulder joint polarity: 0 - caput humeri convex; 1 - caput humeri concave. 88 Caput humeri: 0 - almost flat; 1 - ball-shaped.
89 Body of humerus: 0 - cylindrical; 1 - flattened rectangular. 90 Deltoid and supinator process on humerus: 0 - present; 1 - absent. 91 Radials: 0 - jointed; 1 - unjointed.
92 Basal segments of lepidotrichia elongated; 0 - no; 1 - yes. 93 Dorsal and anal fins: 0 - present; 1 - absent.
94 Posterior radials in posterior dorsal fin: 0 - not branched; 1 - branched. 95 Caudal fin: 0 - heterocercal; 1 - diphycercal.
96 Epichordal radials in caudal fin: 0 - absent; 1 - present. 97 Basal scutes: 0 - absent; 1 - present. 98 Scale morphology: 0 - rhomboid with internal ridge; 1 -round.
99 Supraneural spines: 0 - present; 1 - absent.
III, Data matrix of ref. 11 with new codings for Kenichthys and Character 39 in bold and underlined. Characters 7 and 98 are redefined.
1 11111 11112 22222 22223 33333 33334 44444 CHARACTER: 12345 67890 12345 67890 12345 67890 12345 67890 12345
Porolepis 20001 00000 10032 00000 00012 00000 ?0100 10101 01000 Powichthys 20000 00010 10011 0?0?? ??0?2 00000 ?0?00 01100 01000 Youngolepis 20001 00010 10010 00?00 00011 00000 ?0100 101?0 01?0? Diabolepis ????? ????1 00??2 1??00 01000 00001 ?0?01 101?0 00?00 Dipterus ?0?0? ????1 ?0??2 1?110 200?0 ??001 ???01 1?1?0 01000 Cabonnichthys ?100? ??100 01112 01?02 20110 11110 02?1? 01010 01100 Mandageria ?10?? ???00 01?12 01?02 20110 11110 0311? 01010 01100 Eusthenodon 010?0 01100 01112 0??02 2011? ?1110 03?1? 01010 01100 Eusthenopteron ?1000 01100 00112 01102 20110 10110 0311? 00000 01100 Plat'ichthys 01001 01100 01012 0??02 20110 10110 02?1? ??000 01100 Jarvikina ?10?1 0?100 00?12 0??02 20110 10110 0211? 01000 01100 Tristichopterus ????? 0???0 00??2 0??0? ???1? ?0?10 ?2?1? 000?0 010?0 Koharalepis ????? ????0 ???12 0?10? ???1? ???10 ?1?00 010?1 01?00 Canowindra ????? ????0 ????? ????? ????? ???10 ?0?1? 010?1 01?00 Beelarongia ????? ????0 ????? ????? ????? ???10 ?0?00 000?1 001?0 Gyroptychius 1???0 0?000 0?012 0??00 10010 10110 00000 00000 01100 Medoevia 11000 01000 00012 00000 10010 10110 ?0000 00000 01??? Gogonasus 10?00 01000 00011 00000 20010 10110 01000 000?0 00100
Osteolepis ????? ????0 00?12 0??0? ????? 10?10 01000 00000 00100
Megalichthys 0100? 11000 01012 00000 11010 11110 10?00 1???0 00100
Ectosteorhachis 110?? ?1010 010?2 0??00 11010 11110 10000 1???0 0?100
Cladarosymblema 11000 11000 01012 0??00 11010 11110 10000 10??0 00100
Barameda ????? ????0 01??2 0??00 ?001? ?1110 00?1? 00000 10010 Gooloogongia 1???? ?1?00 01??2 0???? ????? ?0110 00?1? 01000 10010 Panderichthys 01111 01100 01022 00?01 20110 10110 0301? 010?0 01001
Acanthostega 11011 01100 01222 02110 20010 10110 02?1? 000?? 0?211
Ichthyostega 11011 01100 01222 02110 20010 10110 02?1? 000?? 0?211
Kenichthys 10000 01010 00012 00??0 ?00?0 10000 00?00 001?0 00???
Glyptolepis 2?000 00000 10031 00000 00012 00000 ?011? 10101 00000
44445 55555 55556 66666 66667 77777 77778 88888 88889 CHARACTER: 67890 12345 67890 12345 67890 12345 67890 12345 67890
Porolepis 00?10 1000? 01001 10000 01010 11000 11011 10101 ????? Powichthys 00000 ????0 01001 ???00 01111 01010 11111 1110? ????? Youngolepis 00000 0000? 01?00 011?? 10111 00111 01110 0110? ????? Diabolepis 1??0? ????0 ?100? ????? 10110 00??? ??0?? ?11?? ????? Dipterus 11?00 ?1000 ?100? 00000 01??0 00??0 00??0 01111 11??? Cabonnichthys 01?01 10010 ?0100 00010 0?00? 11??? ?10?2 ??010 00001 Mandageria 01?01 10111 ?0100 00011 0?00? 11??? 110?2 ???10 00001 Eusthenodon 01?01 10111 10100 00010 0?00? 1???? ????? ??0?0 ????? Eusthenopteron 01?01 00000 00000 00010 0100? 11000 11002 00010 00001 Plat'ichthys 01?0? 1011? 10100 000?? 0?00? 1???? ????? ??010 ????? Jarvikina 01?0? ?0000 00100 00010 0???? 11000 110?2 ??0?? ????? Tristichopterus 01?01 00000 ?0000 00010 0???? 1???? ????? ???10 00??1 Koharalepis 00000 00010 ?0000 00011 01??1 1???? ????? ????? 0????
Canowindra 00000 ?0010 ?0000 00011 0???? 1???? ????? ????0 0???? Beelarongia 00000 ?0010 ?0000 00011 0???? 1???? ????? ???0? ??001 Gyroptychius 00000 00000 00000 00010 01001 11000 110?2 ?0010 0???? Medoevia 00000 00000 00000 00010 01000 11000 11002 0?000 ?0001 Gogonasus 00000 00000 00000 00010 0100? 11000 11002 0?00? ?0??? Osteolepis 00000 00000 00000 00010 01001 11000 110?2 ??00? 0???? Megalichthys 00000 00000 00000 00010 0100? 11000 110?2 ??000 00001 Ectosteorhachis 00000 00?00 ?000? 0??10 0100? 11000 110?2 ????? 0????
Cladarosymblema 00000 00000 00000 00010 01001 11000 11002 0?000 00??? Barameda 00100 ??000 ?000? ???11 0100? 11??? ????? ???0? 00101 Gooloogongia 00100 00000 ?0000 00011 0?00? 11??? ????? ????1 0???? Panderichthys 01?00 1?000 00010 00010 0?00? 010?0 1100? 0?010 0001? Acanthostega 01?00 1100? 00010 000?? 0?00? 00??0 0?0?? ??0?? 00011 Ichthyostega 01?00 1100? 00010 000?? 0?00? 00??? 0?0?? ??0?? 00011 Kenichthys 00000 0000? 00000 01110 01111 110?0 ?10?2 0010? ?????
Glyptolepis 00010 1000? 0?001 10000 0101? 11000 11011 10001 11000
99999 9999
CHARACTER: 12345 6789
Porolepis ????? ??0?
Powichthys ????? ??0?
Youngolepis ????? ??0?
Diabolepis ????? ????
Dipterus 01010 ?0?0
Cabonnichthys 100?1 111?
Mandageria 10001 101?
Eusthenodon ?00?? ??1?
Eusthenopteron 10001 0111
Plat'ichthys ????? ????
Jarvikina ????? ??1?
Tristichopterus 10000 0111
Koharalepis ?0??? ??0?
Canowindra ?00?0 ?01?
Beelarongia ?0??? ?10?
Gyroptychius ?00?1 ?101
Medoevia ????? ??1?
Gogonasus ????? ??0?
Osteolepis 10000 ?101
Megalichthys 10000 010?
Ectosteorhachis ????? ??0?
Cladarosymblema ?0??? ??0?
Barameda 01??? ??1?
Gooloogongia ?10?0 ?01?
Panderichthys 101?1 ?001
Acanthostega 0?101 1001
Ichthyostega 0?101 10?1
Kenichthys ????? ?10?
Glyptolepis 01010 0010
IV, Consensus of 18 most parsimonious trees based on the data matrix of ref.11 with
complementary codings for Kenichthys and the redefinition of Characters 7 and 98. Character 39 is re-coded for 9 genera. Bremer support values are shown at nodes. Tree
length, 194 steps; Consistency index (CI), 0.572; Homoplasy index (HI), 0.428; CI
excluding uninformative characters, 0.556; HI excluding uninformative characters,
0.444; Retention index (RI), 0.778; Rescaled consistency index (RC), 0.445.
