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
97
98
99
Epichordal radials in caudal fin: 0 - absent; 1 - present.
Basal scutes: 0 - absent; 1 - present.
Scale morphology: 0 - rhomboid with internal ridge; 1 -round.
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.
CHARACTER:
1 11111 11112 22222 22223 33333 33334 44444
12345 67890 12345 67890 12345 67890 12345 67890 12345
Porolepis
Powichthys
Youngolepis
Diabolepis
Dipterus
Cabonnichthys
Mandageria
Eusthenodon
Eusthenopteron
Plat'ichthys
Jarvikina
Tristichopterus
Koharalepis
Canowindra
Beelarongia
Gyroptychius
Medoevia
Gogonasus
Osteolepis
Megalichthys
Ectosteorhachis
Cladarosymblema
Barameda
Gooloogongia
Panderichthys
Acanthostega
Ichthyostega
Kenichthys
Glyptolepis
20001
20000
20001
?????
?0?0?
?100?
?10??
010?0
?1000
01001
?10?1
?????
?????
?????
?????
1???0
11000
10?00
?????
0100?
110??
11000
?????
1????
01111
11011
11011
10000
2?000
CHARACTER:
44445 55555 55556 66666 66667 77777 77778 88888 88889
67890 12345 67890 12345 67890 12345 67890 12345 67890
Porolepis
Powichthys
Youngolepis
Diabolepis
Dipterus
Cabonnichthys
Mandageria
Eusthenodon
Eusthenopteron
Plat'ichthys
Jarvikina
Tristichopterus
Koharalepis
00?10
00000
00000
1??0?
11?00
01?01
01?01
01?01
01?01
01?0?
01?0?
01?01
00000
00000
00010
00010
????1
????1
??100
???00
01100
01100
01100
0?100
0???0
????0
????0
????0
0?000
01000
01000
????0
11000
?1010
11000
????0
?1?00
01100
01100
01100
01010
00000
1000?
????0
0000?
????0
?1000
10010
10111
10111
00000
1011?
?0000
00000
00010
10032
10011
10010
00??2
?0??2
01112
01?12
01112
00112
01012
00?12
00??2
???12
?????
?????
0?012
00012
00011
00?12
01012
010?2
01012
01??2
01??2
01022
01222
01222
00012
10031
01001
01001
01?00
?100?
?100?
?0100
?0100
10100
00000
10100
00100
?0000
?0000
00000
0?0??
00?00
1??00
1?110
01?02
01?02
0??02
01102
0??02
0??02
0??0?
0?10?
?????
?????
0??00
00000
00000
0??0?
00000
0??00
0??00
0??00
0????
00?01
02110
02110
00??0
00000
10000
???00
011??
?????
00000
00010
00011
00010
00010
000??
00010
00010
00011
00012
??0?2
00011
01000
200?0
20110
20110
2011?
20110
20110
20110
???1?
???1?
?????
?????
10010
10010
20010
?????
11010
11010
11010
?001?
?????
20110
20010
20010
?00?0
00012
01010
01111
10111
10110
01??0
0?00?
0?00?
0?00?
0100?
0?00?
0????
0????
01??1
00000
00000
00000
00001
??001
11110
11110
?1110
10110
10110
10110
?0?10
???10
???10
???10
10110
10110
10110
10?10
11110
11110
11110
?1110
?0110
10110
10110
10110
10000
00000
11000
01010
00111
00???
00??0
11???
11???
1????
11000
1????
11000
1????
1????
?0100
?0?00
?0100
?0?01
???01
02?1?
0311?
03?1?
0311?
02?1?
0211?
?2?1?
?1?00
?0?1?
?0?00
00000
?0000
01000
01000
10?00
10000
10000
00?1?
00?1?
0301?
02?1?
02?1?
00?00
?011?
11011
11111
01110
??0??
00??0
?10?2
110?2
?????
11002
?????
110?2
?????
?????
10101
01100
101?0
101?0
1?1?0
01010
01010
01010
00000
??000
01000
000?0
010?1
010?1
000?1
00000
00000
000?0
00000
1???0
1???0
10??0
00000
01000
010?0
000??
000??
001?0
10101
10101
1110?
0110?
?11??
01111
??010
???10
??0?0
00010
??010
??0??
???10
?????
01000
01000
01?0?
00?00
01000
01100
01100
01100
01100
01100
01100
010?0
01?00
01?00
001?0
01100
01???
00100
00100
00100
0?100
00100
10010
10010
01001
0?211
0?211
00???
00000
?????
?????
?????
?????
11???
00001
00001
?????
00001
?????
?????
00??1
0????
Canowindra
Beelarongia
Gyroptychius
Medoevia
Gogonasus
Osteolepis
Megalichthys
Ectosteorhachis
00000
00000
00000
00000
00000
00000
00000
00000
?0010
?0010
00000
00000
00000
00000
00000
00?00
?0000
?0000
00000
00000
00000
00000
00000
?000?
00011
00011
00010
00010
00010
00010
00010
0??10
0????
0????
01001
01000
0100?
01001
0100?
0100?
1????
1????
11000
11000
11000
11000
11000
11000
?????
?????
110?2
11002
11002
110?2
110?2
110?2
????0
???0?
?0010
0?000
0?00?
??00?
??000
?????
0????
??001
0????
?0001
?0???
0????
00001
0????
Cladarosymblema
Barameda
Gooloogongia
Panderichthys
Acanthostega
Ichthyostega
Kenichthys
Glyptolepis
00000
00100
00100
01?00
01?00
01?00
00000
00010
00000
??000
00000
1?000
1100?
1100?
0000?
1000?
00000
?000?
?0000
00010
00010
00010
00000
0?001
00010
???11
00011
00010
000??
000??
01110
10000
01001
0100?
0?00?
0?00?
0?00?
0?00?
01111
0101?
11000
11???
11???
010?0
00??0
00???
110?0
11000
11002
?????
?????
1100?
0?0??
0?0??
?10?2
11011
0?000
???0?
????1
0?010
??0??
??0??
0010?
10001
00???
00101
0????
0001?
00011
00011
?????
11000
CHARACTER:
99999 9999
12345 6789
Porolepis
Powichthys
Youngolepis
Diabolepis
Dipterus
Cabonnichthys
Mandageria
Eusthenodon
Eusthenopteron
Plat'ichthys
Jarvikina
Tristichopterus
Koharalepis
Canowindra
Beelarongia
Gyroptychius
Medoevia
Gogonasus
Osteolepis
Megalichthys
Ectosteorhachis
Cladarosymblema
Barameda
Gooloogongia
Panderichthys
Acanthostega
Ichthyostega
Kenichthys
Glyptolepis
?????
?????
?????
?????
01010
100?1
10001
?00??
10001
?????
?????
10000
?0???
?00?0
?0???
?00?1
?????
?????
10000
10000
?????
?0???
01???
?10?0
101?1
0?101
0?101
?????
01010
??0?
??0?
??0?
????
?0?0
111?
101?
??1?
0111
????
??1?
0111
??0?
?01?
?10?
?101
??1?
??0?
?101
010?
??0?
??0?
??1?
?01?
?001
1001
10?1
?10?
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.