A four-legged snake from the Early Cretaceous of Gondwana

Abstract

Snakes are a remarkably diverse and successful group today, but their evolutionary origins are obscure. The discovery of snakes with two legs has shed light on the transition from lizards to snakes, but no snake has been described with four limbs, and the ecology of early snakes is poorly known. We describe a four-limbed snake from the Early Cretaceous (Aptian) Crato Formation of Brazil. The snake has a serpentiform body plan with an elongate trunk, short tail, and large ventral scales suggesting characteristic serpentine locomotion, yet retains small prehensile limbs. Skull and body proportions as well as reduced neural spines indicate fossorial adaptation, suggesting that snakes evolved from burrowing rather than marine ancestors. Hooked teeth, an intramandibular joint, a flexible spine capable of constricting prey, and the presence of vertebrate remains in the guts indicate that this species preyed on vertebrates and that snakes made the transition to carnivory early in their history. The structure of the limbs suggests that they were adapted for grasping, either to seize prey or as claspers during mating. Together with a diverse fauna of basal snakes from the Cretaceous of South America, Africa, and India, this snake suggests that crown Serpentes originated in Gondwana.
Copyright © 2015, American Association for the Advancement of Science.

Full text

removal, which has been shown to be the rate-
determining step on similar surfaces (12–14,17).
Relative to their core-shell precursors, the nano-
cage models showed substantially enhanced ac-
tivity, which is attributed to the shortening of Pt-Pt
interatomic distances (table S2).
We evaluated the long-term stability of the
catalysts through an accelerated durability test
(Fig. 4, C and D). The Pt octahedral nanocages
showed the best performance, with the ORR mass
activity only reduced by 36% after 10,000 cycles,
still showing 3.4-fold enhancement relative to the
pristine Pt/C. The ECSAs of the cubic and octa-
hedral nanocages only dropped by 13 and 6% after
5000 cycles and by 32 and 23% after 10,000 cycles,
respectively. During the durability test, the holes
in the walls of the nanocages were slightly en-
larged (fig. S7). These results demonstrate that the
excellent durability associated with the core-shell
catalysts was not affected by the selective removal
of Pd cores.
REFERENCES AND NOTES
1. J. Chen, B. Lim, E. P. Lee, Y. Xia, Nano Today 4,81–95
(2009).
2. F. A. de Bruijn, V. A. T. Dam, G. J. M. Janssen, Fuel Cells
(Weinh.) 8,3–22 (2008).
3. X. Lu et al., Nano Lett. 7, 1764–1769 (2007).
4. S. Xie et al., Angew. Chem. Int. Ed. Engl. 51, 10266–10270
(2012).
5. C. Chen et al., Science 343, 1339–1343 (2014).
6. A. Funatsu et al., Chem. Commun. (Camb.) 50, 8503–8506
(2014).
7. H. Li et al., Angew. Chem. Int. Ed. Engl. 52, 8368–8372
(2013).
8. H. Duan et al., Nat. Commun. 5, 3093 (2014).
9. R. R. Adzic et al., Top. Catal. 46, 249–262 (2007).
10. K. Sasaki et al., Nat. Commun. 3, 1115 (2012).
11. M. Shao et al., Chem. Commun. (Camb.) 49, 9030–9032
(2013).
12. S. Xie et al., Nano Lett. 14, 3570–3576 (2014).
13. J. Park et al., ACS Nano 9, 2635–2647 (2015).
14. X. Wang et al., Nat. Commun. 6, 7594 (2015).
15. Y. Yin et al., Science 304,711–714 (2004).
16. M. Jin et al., Nano Res. 4,83–91 (2011).
17. Materials and methods are available as supplementary
materials on Science Online.
18. X. Xia et al., Proc. Natl. Acad. Sci. U.S.A. 110, 6669–6673
(2013).
19. M. Heggen, M. Oezaslan, L. Houben, P. Strasser, J. Phys. Chem.
C116, 19073–19083 (2012).
20. J. Erlebacher, M. J. Aziz, A. Karma, N. Dimitrov, K. Sieradzki,
Nature 410, 450–453 (2001).
21. V. A. Baheti, R. Ravi, A. Paul, J. Mater. Sci. Mater. Electron. 24,
2833–2838 (2013).
22. N. M. Markovic, P. N. Ross, Surf. Sci. Rep. 45,117–229
(2002).
23. J. Zhang, H. Yang, J. Fang, S. Zou, Nano Lett. 10, 638–644
(2010).
24. J. Wu, A. Gross, H. Yang, Nano Lett. 11, 798–802
(2011).
25. S.-I. Choi et al., Nano Lett. 13, 3420–3425 (2013).
26. C. Cui, L. Gan, M. Heggen, S. Rudi, P. Strasser, Nat. Mater. 12,
765–771 (2013).
27. L. Gan et al., Science 346, 1502–1506 (2014).
28. B. Han et al., Energy Environ. Sci. 8, 258–266 (2015).
ACKNOWL EDGMENTS
The syntheses were supported by start-up funds from the
Georgia Institute of Technology (to Y.X.). As jointly supervised
PhD students from Xiamen University, L.Z. and X.W. were also
partially supported by fellowships from the China Scholarship
Council. The theoretical modeling work at University of
Wisconsin–Madison was supported by the U.S. Department of
Energy (DOE)–Basic Energy Sciences (BES), Office of Chemical
Sciences, grant DE-FG02-05ER15731. Calculations were
performed at supercomputing centers located at the
Environmental Molecular Sciences Laboratory, which is
sponsored by the DOE Office of Biological and Environmental
Research at the Pacific Northwest National Laboratory; Center
for Nanoscale Materials at Argonne National Laboratory,
supported by DOE contract DE-AC02-06CH11357; and National
Energy Research Scientific Computing Center, supported by
DOE contract DE-AC02-05CH11231. Part of the electron
microscopy work was performed through a user project
supported by the Oak Ridge National Laboratory’s Center for
Nanophase Materials Sciences, which is a DOE Office of Science
User Facility. J.L. gratefully acknowledges the support by Arizona
State University and the use of facilities in the John M. Cowley
Center for High Resolution Electron Microscopy at Arizona State
University. Data described can be found in the main figures and
supplementary materials. The authors declare no conflict of
interests.
SUPPLEMENTARY MATERIALS
www.sciencemag.org/content/349/6246/412/suppl/DC1
Materials and Methods
Figs. S1 to S8
Tables S1 to S3
References (29–37)
8 March 2015; accepted 15 June 2015
10.1126/science.aab0801
EVOLUTION
A four-legged snake from the Early
Cretaceous of Gondwana
David M. Martill,
1
Helmut Tischlinger,
2
Nicholas R. Longrich
3
Snakes are a remarkably diverse and successful group today, but their evolutionary origins are
obscure. The discovery of snakes with two legs has shed light on the transition from lizards to
snakes, but no snake has been described with four limbs, and the ecology of early snakes is
poorly known. We describe a four-limbed snake from the Early Cretaceous (Aptian) Crato
Formation of Brazil.The snake has a serpentiform body plan with an elongate trunk, short tail,
and large ventral scales suggesting characteristic serpentine locomotion, yet retains small
prehensile limbs. Skull and body proportions as well as reduced neural spines indicate fossorial
adaptation, suggesting that snakes evolved from burrowing rather than marine ancestors.
Hooked teeth, an intramandibular joint, a flexible spine capable of constricting prey, and the
presence of vertebrate remains in the guts indicate that this species preyed on vertebrates and
that snakes made the transition to carnivory early in their history.The structure of the limbs
suggests that they were adapted for grasping, either to seize prey or as claspers during mating.
Together with a diverse fauna of basal snakes from the Cretaceous of South America, Africa, and
India, this snake suggests that crown Serpentes originated in Gondwana.
Snakes are among the most diverse groups
of tetrapods, with >3000 extant species ex-
ploiting a remarkable range of niches (1).
Snakes inhabit deserts and rainforests, moun-
tains and oceans; and despite lacking limbs,
employ an extraordinary range of locomotor
styles, including crawling, burrowing, climbing,
swimming, and even gliding (1). All snakes are
predators, but they consume a wide range of prey,
from insects to large mammals (1). This diversity
is made possible by a specialized body plan, in-
cluding an elongate body with reduced limbs, a
flexible skull and ribs to swallow large prey (2),
and a specialized forked tongue and vomero-
nasal organ to detect chemical gradients (1). The
origins of this body plan remain unclear, how-
ever (1). One scenario holds that it originated in
a marine environment, whereas others argue that
it results from adaptation for a fossorial lifestyle.
New fossils (2–4), including snakes with hindlimbs
(5,6), have shed light on the lizard-to-snake
transition, but no snake has been reported with
four limbs. The ecology of early snakes is also un-
certain. Although alethinophidians are primarily
carnivorous (1), Typhlopidae and Anomal epididae,
which are basal with respect to Alethinophidia
(7–9), are insectivorous (1). This suggests that
early snakes were insectivores, although adap-
tations for carnivory in stem snakes (2) suggest
that carnivory may be primitive (2,5).
Here we report a fossil snake from the Early
Cretaceous of Gondwana, which sheds light on
these issues. Tetrapodophis amplectus gen. et sp.
nov. (holotype BMMS BK 2-2) is distinguished
from all other snakes by the following combina-
tion of characters: 160 precaudal and 112 caudal
vertebrae, short neural spines, four limbs, meta-
podials short, penultimate phalanges hyperelon-
gate and curved, phalangeal formula 2?-3-3-3-3?
(manus) 2-3-3-3-3 (pes).
The fossil (Fig. 1) comes from the Nova Olinda
Member of the Early Cretaceous (Aptian) Crato
Formation, Ceará, Brazil (10). The specimen is pre-
served on laminated limestone as part and coun-
terpart. The matrix is typical of the Nova Olinda
Member in being composed of fine-grained lam-
inated micrite with elongated pellets on the surface
of the slab representing coprolites of the fish Dastilbe.
As is typical of Crato vertebrates, the skeleton is
articulated and the bones are a translucent orange-
brown color; soft tissues are also preserved.
The snake affinities of Tetrapodophis are dem-
onstrated by derived features of the skull, axial
416 24 JULY 2015 •VOL 349 ISSUE 6246 sciencemag.org SCIENCE
1
School of Earth and Environmental Sciences, University of
Portsmouth, Portsmouth PO1 3QL, UK.
2
Tannenweg 16,
85134 Stammham, Germany.
3
Department of Biology and
Biochemistry and Milner Centre for Evolution, University of
Bath, Claverton Down, Bath BA2 7AY, UK.
RESEARCH |REPORTS
on July 23, 2015www.sciencemag.orgDownloaded from on July 23, 2015www.sciencemag.orgDownloaded from on July 23, 2015www.sciencemag.orgDownloaded from on July 23, 2015www.sciencemag.orgDownloaded from

skeleton, limbs, integument, and even behavior
(Figs. 2 to 4) (* = snake autapomorphy). Snake-
like features of the skull include a short rostrum,
alongbraincase,andanasaldescendinglamina.
The mandible is bowed, with a deep subdental
ridge and an intramandibular joint formed by a
concave splenial cotyle contacting the angular, as
in Dinilysia (11). Teeth exhibit the ophidian con-
dition, being unicuspid and hooked, with expanded
bases. Implantation is subacrodont, with teeth
separated by interdental ridges; replacement
teeth are oriented subhorizontally.* Snake-like
features of the axial skeleton include an elon-
gate trunk with over 150 vertebrae,* zygosphene-
zygantrum articulations, a vaulted neural arch
with posterolateral tuberosities,* short neural
spines, haemal keels, large subcentral fossae/
foramina, tubercular processes of the ribs, and
lymphapophyses. The ilium is long and slender
as in other snakes; the fibula is bowed as in Najash
(5) and Simoliophiidae (12). Transverse belly scales*
are preserved, and the presence of a vertebrate
in the gut suggests a snake-like feeding strategy
in which proportionately large prey are ingested
whole. Although many of these features occur
in other long-bodied squamates, only snakes
exhibit all of them, and many of these characters
are uniquely ophidian.
Tetrapodophis exhibits a number of primitive
characters, however. The nasal is L-shaped, as in
Dinilysia (11) and Simoliophiidae. The maxilla’s
facial process is reduced as compared to those of
lizards but tall relative to those of crown snakes,
as in Coniophis (2). The subdental ridge is shal-
low posteriorly, a primitive feature shared with
Najash (5)andConiophis (2). Unlike crown snakes,
in which a convex splenial condyle articulates
with the angular, the splenial exhibits a concave
cotyle, as in Dinilysia (11). Prezygapophyseal
processes are absent as in other stem snakes;
synapophyses are kidney-shaped, lacking the dis-
tinct condyle and planar cotyle of alethinophidians.
Strikingly, Tetrapodophis retains reduced but ap-
parently functional forelimbs and hindlimbs.
To test Tetrapodophis’ophidian affinities, we
used a morphological matrix (13,14)toconduct
four phylogenetic analyses: with and without mo-
lecular backbone constraint (8) and with equal
and implied weighting (15). In each analysis,
Tetrapodophis emerges as a basal snake (Fig. 5)
butisclosertomodernsnakesthantheputative
Jurassic-Cretaceous stem ophidians Parviraptor,
Diablophis,Portugalophis,andEophis.Whena
molecular backbone is used (Fig. 5), Tetrapodophis
emerges as sister to Coniophis, and snakes emerge
as sister to the Mosasauria; i.e., Pythonomorpha,
as in a recent combined analysis (7).
As the only known four-legged snake, Tetra-
podophis sheds light on the evolution of snakes
from lizards. Tetrapodophis lacks aquatic adap-
tations (such as pachyostosis or a long, laterally
compressed tail) and instead exhibits features of
fossorial snakes and lizards: a short rostrum and
elongation of the postorbital skull, a long trunk
and short tail (16,17), short neural spines (18),
and highly reduced limbs (16,17). Tetrapodophis
therefore supports the hypothesis tha t snakes
ev olved from burrowing (2,5,6) rather than ma-
rine (19) ancestors. Although the current anal-
ysis suggests a sister-group relationship between
Mosasauria and Serpentes, Cretaceous aquatic
snakes (Simoliophiidae) are recovered nested
within crown Serpentes, and aquatic habits are
therefore derived (2,7).
Tetrapodophis also sheds light on the evolu-
tion of snake feeding. Tetrapodophis exhibits adap-
tations for carnivory, including recurved claw-like
teeth to seize large prey and an intramandibular
joint allowing the gape to expand to swallow
large prey. Along with the presence of a vertebrate
in the gut, these feature show that Tetrapodophis
preyed on vertebrates. Similar adaptations oc-
cur in other early snakes (2,11), suggesting that
snakes made the transition to carnivory early in
their history and that the insectivorous lifestyle
of typhlopids and anomalolepidids is derived.
The structure of the spine may represent an-
other such adaptation for carnivory. Elongate
bodies and reduced limbs evolved many times
among squamates (13,17), occurring in burrowing
SCIENCE sciencemag.org 24 JULY 2015 •VOL 349 ISSUE 6246 417
sp
imj
sdr ld rd
rm
lm pm
nas fp
par
fr
1 mm 1 mm
sp sdr
ld
rd
mec
dt
rep
idr
mt
Fig. 2. T. amplectus, skull and jaws. (A) Skull. (B) Left mandible in medial view. Abbreviations: dt, dentary tooth; fp, facial process of maxilla, fr, frontal; idr,
interdental ridges; imj, intramandibular joint lm, left maxilla, ld, left dentary; mt, maxillary teeth; nas, nasal, par, parietal; pm, premaxilla; rd, right dentary; rd,
right dentary; rep, replacement teeth; sdr, subdental ridge; sp, splenial.
10 mm
Fig. 1. T. amplectus, holotype part and counterpart. (A) Counterpart, showing skull and skeleton
impression. (B) Main slab, showing skeleton and skull impression.
RESEARCH |REPORTS

and terrestrial forms (17)aswellasinaquatic
mosasaurs. Yet snakes are unique among long-
bodied squamates in having over 150 precaudal
vertebrae. This permits extreme flexibility of the
spinal column, so that the entire body can coil
into tight loops. The fact that other long-bodied
squamateslackthisfeaturesuggeststhatitisnot
related to locomotion. We propose that the in-
creased number of trunk vertebrae may be an
adaptation allowing the body to be used to con-
strict prey. Tetrapodophis exhibits both an increased
number of precaudal vertebrae and a high degree
of flexibility, with the body forming a tight coil
anteriorly and a series of sinuous curves poste-
riorly, suggesting that constriction was developed
even in the earliest snakes.
The structure of the limbs may represent an-
other predatory adaptation. The snake-like spine
and reduced limbs of Tetrapodophis suggest that
the animal engaged in characteristic serpentine
locomotion, with the limbs playing little or no
role in locomotion. However, the specialized struc-
ture of the limbs suggests that they were func-
tional. Given Tetrapodophis’presumed fossorial
or semifossorial habits, digging is a plausible
function, but the limbs lack fossorial specializa-
tions. Instead, the manus and pes exhibit slender
isodactyl digits with hyperelongate penultimate
phalanges and abbreviated proximal phalanges.
Thissuiteofcharactersrecallstheprehensilefeet
of scansorial birds, sloths (20), and bats, suggest-
ing a grasping or hooking function. The limbs
may have functioned for grasping prey, or per-
haps mates. Climbing is another possibility, al-
though the low neural spines seem inconsistent
with this function. Regardless, Tetrapodophis
shows that after the initial evolution of serpen-
tine locomotion, the limbs were repurposed for
another function.
Finally, Tetrapodophis sheds light on the geo-
graphic origin of snakes. The Serpentes, Iguania,
and Anguimorpha form the Toxicofera (7–9), with
the oldest iguanian and anguimorph fossils com-
ing from Laurasia (13). These patterns suggest
that the center of toxicoferan diversification is
Laurasia and that the ancestors of snakes probably
originated there. The identification of possible
stem ophidians from the Jurassic and Early Cre-
taceous of Laurasia (4) would support this hypoth-
esis. However, the most basal divergences within
crown Serpentes, including Anomalolepididae
and Typhlopidae, Aniliidae and Tropidophiidae,
418 24 JULY 2015 •VOL 349 ISSUE 6246 sciencemag.org SCIENCE
mt
mt
as
as
cal
cal
ph
ph
ph
ph
un
un
I
I
II
III
IV V
II
III
IV V
il
il
il
tib
b
b
tib
pes
pes
fem
fem
hu
ra
n
man
ul
f
b
b
fib
fib
tib
tib
pes
pes
fem
fem
fib
fib
sr
lym
il sr
lym
i
i
i
1 mm 1 mm 1 mm
1 mm
1 mm
mc
ph
ph
un
I
II III
IV
V
hu
ra
man
ul
mc
ph
ph
un
I
II III
IV
V
Fig. 4. T. amplectus appendicular morphology. (A) Forelimb. (B) Manus. (C) Hindlimbs and pelvis. (D)Pes.(E) Pelvis. Abbreviations: fem, femur; fib, fibula;
hu, humerus; il, ilium; lym, lymphapophysis; man, manus; mc, metacarpal; mt, metatarsals; ph, phalanges; ra, radius; sr, sacral rib; tib, tibia; ul, ulna; un, ungual.
Fig. 3. T. amplectus
axial column. (A)
Cervicals and anterior
presacrals. (B) Mid-
thorax, showing ventral
scales. (C)Posterior
thorax, showing gut
contents. Abbrevia-
tions: gc, gut contents;
nsp, neural spines;
poz, postzygapophysis;
prz, prezygapophysis;
syn, synapophyses vb,
vertebrate bone; vs,
ventral scales; zga,
zygantrum; zgs,
zygosphene.
nsp poz
zga
zgs
syn
gc
prz
vb
1 mm
1mm
nsp poz
zga
zgs
syn
prz
gc
vb
1 mm
vs
1mm vs
RESEARCH |REPORTS

are endemic to or originate in South America and
Africa, hinting at Gondwanan origins (1). Further-
more, during the middle Cretaceous, Gondwana was
home to a diverse fauna of basal snakes, including
Coniophiidae, Russellophiidae, Madtsoiidae (21),
and Simoliophiidae (22) in the Cenomanian of
Africa, the Cenomanian-Turonian Najash (18,23)in
South America, and now Tetrapodophis from the
Aptian of South America. Snakes are far less diverse
in the Cretaceous of Laurasia, with a single lineage
appearing in the Cenomanian (24)ofNorthAmer-
ica; alethinophidians do not appear until the
Maastrichtian in North America (14)andEurope(25).
These patterns suggest that the Serpentes r epr ese nt
an endemic Gondwanan radiation that saw lim-
ited dispersal to Laurasia during the Cretaceous.
Snakes appear to have been part of a highly
endemic herpetofauna that evolved in the Creta-
ceous in Gondwana. In this fauna, notosuchian
crocodiles (26) and rhynchocephalians (27) played
a major role, whereas squamates appear to have
been less diverse and disparate than in Laurasia.
The exception is the snakes, which radiated to
produce small burrowers, large constrictors,
and aquatic forms (21,22). Much of this herpeto-
fauna appears to have become extinct during
the Cretaceous-Paleogene extinction (Notosuchia)
or was greatly reduced in diversity in the Ceno-
zoic (Rhynchocephalia). Snakes, meanwhile, not
only survived but became diverse and widespread
in the Paleogene (14), perhaps in response to ecol-
ogical release provided by the end-Cretaceous
mass extinction (14).
REFERENCES AND NOTES
1. H. W. Greene, Snakes: the Evolution of Mystery in Nature
(Univ. of California Press, Berkeley, 1997).
2. N. R. Longrich, B.-A. S. Bhullar, J. A. Gauthier, Nature 488,
205–208 (2012).
3. J. D. Scanlon, M. S. Y. Lee, Nature 403, 416–420 (2000).
4. M. W. Caldwell, R. L. Nydam, A. Palci, S. Apesteguía,
Nat. Commun. 6, 5996 (2015).
5. S. Apesteguía, H. Zaher, Nature 440, 1037–1040 (2006).
6. E. Tchernov, O. Rieppel, H. Zaher, M. J. Polcyn, L. L. Jacobs,
Science 287, 2010–2012 (2000).
7. T. W. Reeder et al., PLOS ONE 10, e0118199 (2015).
8. R.A.Pyron,F.T.Burbrink,J.J.Wiens,BMC Evol. Biol. 13,93(2013).
9. J. J. Wiens et al., Biol. Lett. 8, 1043–1046 (2012).
10. U. Heimhofer, D. M. Martill, in The Crato Fossil Beds
of Brazil, D. M. Martill, G. Bechly, R. F. Loveridge, Eds.
(Cambridge Univ. Press, Cambridge, 2007), pp. 44–62.
11. H.Zaher,C.A.Scanferla,Zool. J. Linn. Soc. 164,194–238 (2012).
12. M. S. Lee, M. W. Caldwell, Philos. Trans. R. Soc. London Ser. B
353, 1521–1552 (1998).
13. J. Gauthier, M. Kearney, J. A. Maisano, O. Rieppel,
A. Behlke, Bull. Yale Peabody Mus. 53,3–308 (2012).
14. N. R. Longrich, B. A. Bhullar, J. A. Gauthier, Proc. Natl. Acad.
Sci. U.S.A. 109, 21396–21401 (2012).
15. P. A. Goloboff, J. M. Carpenter, J. S. Arias, D. R. M. Esquivel,
Cladistics 24, 758–773 (2008).
16. J. J. Wiens, J. L. Slingluff, Evolution 55, 2303–2318 (2001).
17. J.J.Wiens,M.C.Brandley,T.W.Reeder,Evolu tion 60,123–141 (200 6).
18. H. Zaher, S. Apesteguía, C. A. Scanferla, Zool. J. Linn. Soc. 156,
801–826 (2009).
19. M. W. Caldwell, M. S. Y. Lee, Nature 386, 705–709 (1997).
20. M. Hildebrand, G. Goslow, Analysis of Vertebrate Structure
(Wiley, New York, 2001).
21. J.-C. Rage, C. Werner, Palaeontol. Africana 35,85–110 (1999).
22. J.-C. Rage, D. B. Dutheil, Palaeontographica Abteilung A,1–22 (2008).
23. J.-C. Rage, A. M. Albino, Neues Jahrb. Geol. Palaontol.
Monatsh. 1989, 433–447 (1989).
24. J. D. Gardner,R. L. Cifelli, Spec. Pap. Palaeontol. 60,87–100 (1999).
25. J.-C. Rage, C. R.'Acad.Sc. Sér. 2 Sci.Terre Planètes 322,
603–608 (1996).
26. P. M. O’Connor et al., Nature 466, 748–751 (2010).
ACKNOWL EDGMENTS
Thanks to B. A. S. Bhullar, J. A. Gauthier, and J. C. Rage for
discussions and to the anonymous reviewers whose comments
improved this paper. The holotype (BMMS BK 2-2) is housed at
the Bürgermeister-Müller-Museum, Solnhofen, Germany.
SUPPLEMENTARY MATERIALS
www.sciencemag.org/content/349/6246/416/suppl/DC1
Supplementary Text
Figs. S1 to S7
Table S1
References (27–44)
Character-Taxon Matrix
Constraint Tree
23 February 2015; accepted 16 June 2015
10.1126/science.aaa9208
SCIENCE sciencemag.org 24 JULY 2015 •VOL 349 ISSUE 6246 419
SCOLECOPHIDIA
ANGUIMORPHA
MOSASAURIA
IGUANIA
Coniophis precedens
ANILIIDAE
TROPIDOPHIIDAE
CALABARIIDAE
UNGALIOPHIINAE
ERYCINAE
BOINAE
CYLINDROPHIIDAE
ANOMOCHILIDAE
UROPELTIDAE
XENOPELTIDAE
LOXOCEMIDAE
PYTHONIDAE
XENODERMATIDAE
BOLYERIIDAE
ACROCHORDIDAE
PAREATIDAE
VIPERIDAE
HOMALOPSIDAE
LAMPROPHIIDAE
ELAPIDAE
COLUBRIDAE
ALETHINOPHIDIA
SERPENTES
PYTHONO-
MORPHA
OPHIDIA Tetrapodophis amplectus
Parviraptor estesi
Portugalophis lignites
Diablophis gilmorei
Eophis underwoodi
Dinilysia patagonica
MADTSOIIDAE
Pachyrhachis problematicus
Euopodophis descouensi
Haasiophis terrasanctus
Najash rionegrina
limbs reduced
elongate body
constriction
intramandibular joint
forelimbs lost
70
80
60
50
40
30
20
10
PALAEOGENE NEOGENE
CRETACEOUS
JURASSIC
Oligocene
Eocene
Paleocene
Maastrichtian
Campanian
Santonian
Coniacian
Turonian
Cenomanian
Albian
Aptian
Barremian
Hauterivian
Valanginian
Berriasian
Tithonian
Oxfordian
Callovian
Bathonian
Bajocian
Aalenian
Kimmeridgian
Miocene
Pleistocene
Pliocene
90
100
110
120
130
140
150
160
170
K-Pg
Fig. 5. Phylogenetic position of T. amplectus.
A strict consensus of 85 most parsimonious
trees found using implied weights and molec-
ular constraint is shown (see the supplemen-
tary materials) for a matrix of 632 characters
and 205 taxa.
RESEARCH |REPORTS

DOI: 10.1126/science.aaa9208
, 416 (2015);349 Science et al.David M. Martill
A four-legged snake from the Early Cretaceous of Gondwana
This copy is for your personal, non-commercial use only.
clicking here.colleagues, clients, or customers by , you can order high-quality copies for yourIf you wish to distribute this article to others
here.following the guidelines can be obtained byPermission to republish or repurpose articles or portions of articles
): July 23, 2015 www.sciencemag.org (this information is current as of
The following resources related to this article are available online at
http://www.sciencemag.org/content/349/6246/416.full.html
version of this article at: including high-resolution figures, can be found in the onlineUpdated information and services,
http://www.sciencemag.org/content/suppl/2015/07/23/349.6246.416.DC1.html
can be found at: Supporting Online Material
http://www.sciencemag.org/content/349/6246/416.full.html#related
found at: can berelated to this article A list of selected additional articles on the Science Web sites
http://www.sciencemag.org/content/349/6246/416.full.html#ref-list-1
, 7 of which can be accessed free:cites 32 articlesThis article
http://www.sciencemag.org/content/349/6246/416.full.html#related-urls
1 articles hosted by HighWire Press; see:cited by This article has been
http://www.sciencemag.org/cgi/collection/paleo
Paleontology subject collections:This article appears in the following
registered trademark of AAAS. is aScience2015 by the American Association for the Advancement of Science; all rights reserved. The title CopyrightAmerican Association for the Advancement of Science, 1200 New York Avenue NW, Washington, DC 20005.
(print ISSN 0036-8075; online ISSN 1095-9203) is published weekly, except the last week in December, by theScience
on July 23, 2015www.sciencemag.orgDownloaded from