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‘Crocodylus’ pigotti is a relatively small crocodylid from the Miocene of Rusinga Island in Lake Victoria, Kenya. Known only from one relatively complete skull and limited, fragmentary, referred material, ‘Crocodylus’ pigotti lacks a detailed description. Moreover, recent analyses have shown ‘Crocodylus’ pigotti to be an osteolaemine crocodylid, more closely related to the extant dwarf crocodiles (Osteolaemus) than to true Crocodylus. Here, we describe numerous new remains of ‘Crocodylus’ pigotti recovered from localities within the Fossil Bed Member of the Hiwegi Formation at Kaswanga Point, Rusinga Island. We recovered parts of several individuals and report on previously unknown parts of the anatomy, provide an updated phylogenetic analysis, and reallocate the species ‘Crocodylus’ pigotti to a new genus, Brochuchus.SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at
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New specimens of ‘Crocodylus’ pigotti (Crocodylidae)
from Rusinga Island, Kenya, and generic reallocation of
the species
Jack L. Conrad a b , Kirsten Jenkins c , Thomas Lehmann d , Fredrick K. Manthi e , Daniel
J. Peppe f , Sheila Nightingale g , Adam Cossette h , Holly M. Dunsworth i , William E. H.
Harcourt-Smith b j & Kieran P. Mcnulty c
a Anatomy Department , New York College of Osteopathic Medicine , Northern Boulevard,
Old Westbury, New York , 11568-8000 , U.S.A.
b Department of Vertebrate Paleontology , American Museum of Natural History , Central
Park West at 79th Street, New York , New York , 10024 , U.S.A.
c Department of Anthropology , University of Minnesota , 19th Avenue South, Minneapolis ,
Minnesota , 55455 , U.S.A.
d Senckenberg-Forschungsinstitut und Naturmuseum , Senckenberganlage 25, D-60325 ,
Frankfurt am Main , Germany
e Paleontology Department , National Museums of Kenya , P.O. Box 40658, Nairobi , Kenya
f Department of Geology , Baylor University , One Bear Place #97354, Waco , Texas , 76798 ,
g Department of Anthropology, Graduate School and University Center , City University of
New York , 365 Fifth Avenue, New York , New York , 10016 , U.S.A.
h Evolutionary Anthropology Laboratories , University of Minnesota , 19th Avenue South,
Minneapolis , Minnesota , 55455 , U.S.A.
i Department of Sociology and Anthropology , University of Rhode Island , 10 Chafee Road,
Kingston , Rhode Island , 02881 , U.S.A.
j Department of Anthropology , Lehman College , 250 Bedford Park Boulevard West, Bronx ,
New York , 10468 , U.S.A.
Published online: 07 May 2013.
To cite this article: Jack L. Conrad , Kirsten Jenkins , Thomas Lehmann , Fredrick K. Manthi , Daniel J. Peppe , Sheila
Nightingale , Adam Cossette , Holly M. Dunsworth , William E. H. Harcourt-Smith & Kieran P. Mcnulty (2013): New specimens
of ‘Crocodylus’ pigotti (Crocodylidae) from Rusinga Island, Kenya, and generic reallocation of the species, Journal of
Vertebrate Paleontology, 33:3, 629-646
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Journal of Vertebrate Paleontology 33(3):629–646, May 2013
©2013 by the Society of Vertebrate Paleontology
1Anatomy Department, New York College of Osteopathic Medicine, Northern Boulevard, Old Westbury, New York 11568-8000,
2Department of Vertebrate Paleontology, American Museum of Natural History, Central Park West at 79th Street,
New York, New York 10024, U.S.A.;
3Department of Anthropology, University of Minnesota, 19th Avenue South, Minneapolis, Minnesota 55455, U.S.A.,;;
4Senckenberg-Forschungsinstitut und Naturmuseum, Senckenberganlage 25, D-60325 Frankfurt am Main, Germany,;
5Paleontology Department, National Museums of Kenya, P.O. Box 40658, Nairobi, Kenya,;
6Department of Geology, Baylor University, One Bear Place #97354, Waco, Texas 76798, U.S.A., Daniel;
7Department of Anthropology, Graduate School and University Center, City University of New York, 365 Fifth Avenue, New York,
New York 10016, U.S.A.,;
8Evolutionary Anthropology Laboratories, University of Minnesota, 19th Avenue South, Minneapolis, Minnesota 55455, U.S.A.,;
9Department of Sociology and Anthropology, University of Rhode Island, 10 Chafee Road, Kingston, Rhode Island 02881, U.S.A.,
10Department of Anthropology, Lehman College, 250 Bedford Park Boulevard West, Bronx, New York 10468, U.S.A.,
ABSTRACT—‘Crocodyluspigotti is a relatively small crocodylid from the Miocene of Rusinga Island in Lake Victoria,
Kenya. Known only from one relatively complete skull and limited, fragmentary, referred material, ‘Crocodyluspigotti lacks
a detailed description. Moreover, recent analyses have shown ‘Crocodyluspigotti to be an osteolaemine crocodylid, more
closely related to the extant dwarf crocodiles (Osteolaemus)thantotrueCrocodylus. Here, we describe numerous new re-
mains of ‘Crocodyluspigotti recovered from localities within the Fossil Bed Member of the Hiwegi Formation at Kaswanga
Point, Rusinga Island. We recovered parts of several individuals and report on previously unknown parts of the anatomy,
provide an updated phylogenetic analysis, and reallocate the species ‘Crocodyluspigotti to a new genus, Brochuchus.
SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at
Early Miocene crocodylian fossils from the Hiwegi Forma-
tion of Rusinga Island (Lake Victoria, Kenya) were referred
to the genus Crocodylus and used to erect the novel species
Crocodylus pigotti by Tchernov and Van Couvering (1978). A
nearly complete skull recovered in 1948 from Shackleton Gully
near Kaswanga Point (Fig. 1) is the holotype, but Crocodylus
pigotti is known from numerous, often fragmentary, specimens
housed at the National Museums of Kenya (KNM). Its verte-
brae and osteoderms are abundant in Hiwegi Formation expo-
sures on Rusinga. However, complete elements or individuals are
rare, and the species is known only from one complete skull (the
holotype—NHMUK PV R7729), an incomplete skull (consist-
ing of the snout and antorbital parts of the lower jaws) at KNM
(KNM-RU 23819—previously referred to as Crocodylus cf. pig-
otti in the collection data), and numerous associated fragments
of cranial material and postcrania. Reports of Crocodylus pigotti
from Saudi Arabia (Buffetaut, 1984) are based on an incomplete
*Corresponding author.
set of jaws that may or may not be diagnostic as belonging to or
excluded from this species; this specimen was not considered fur-
ther in this study.
The holotype skull of Crocodylus pigotti is 337 mm long (Tch-
ernov and Van Couvering, 1978). Given that skull length is usu-
ally between one-seventh and one-eighth total body length in ex-
tant crocodylid and alligatorid species (Greer, 1974; Webb and
Messel, 1978; Woodward et al., 1995; Platt et al., 2009), the holo-
type of Crocodylus pigotti represents an individual with a total
length that is estimated to be between 2.4 and 2.6 m. This is inter-
mediate in size between the larger modern African crocodylids
(Crocodylus niloticus, 4 m or more) (Cott, 1961; Waitkuwait,
1989; Grenard, 1991) and the dwarf crocodiles (Osteolaemus; e.g.,
Osteolaemus osborni, under 2 m; Fig. 2) and similar in size to
Mecistops cataphractus (2.5 m) (Waitkuwait, 1989). The snout
is similar in shape to the generalist predator Crocodylus niloti-
cus (Tchernov and Van Couvering, 1978), and Crocodylus pigotti
may have had an ecology similar to that of modern Crocodylus
niloticus (Tchernov and Van Couvering, 1978; Brochu, 2007), or
at least subadults of that species (subadults take relatively small
prey items, including fish and birds, whereas adults are able to
take larger mammals; Hutton, 1987).
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FIGURE 1. Nyang Rise, part of the R5 site at Kaswanga Point, Rusinga
Island, Kenya. Modified after Van Couvering (1972) and Pickford (1986)
using Google Earth (Google Inc., 2011). Dykes are represented as
semiopaque gray bars. Private residences are represented in light gray.
Croc Knob, Shackleton Gully, and Nyang Rise are highlighted as irregu-
lar, dark-gray, areas.
Historically, Crocodylus pigotti has been accepted as a legiti-
mate member of Crocodylus, and even has been used in helping
to reconstruct minimum divergence times for Crocodylus (Tch-
ernov and Van Couvering, 1978; Buffetaut, 1984; Brochu, 2000;
Kotsakis et al., 2004). However, recent phylogenetic analyses
have suggested that Crocodylus pigotti shares a more recent com-
mon ancestor with Osteolaemus than with Crocodylus (Brochu,
2007; Brochu et al., 2010; Brochu and Storrs, 2012), making its
referral to Crocodylus problematic.
Here, we describe newly recovered material referable to
Crocodyluspigotti. The new material comes from near the
base of the Fossil Bed Member of the Hiwegi Formation on
Rusinga Island, Lake Victoria, Kenya (Fig. 1). The fossils come
from a new sublocality we term Nyang Rise (‘nyang’ meaning
‘crocodile’ in the local Luo language) (Fig. 1). At least 10
individuals have been recovered, the remains of which range in
completeness from extremely fragmentary to partial, associated
skeletons. The new material includes parts of 10 skulls along with
multiple appendicular elements, dozens of vertebrae, and many
osteoderms. We apply the new data gleaned from these remains
to a cladistic analysis derived from the recent studies of Brochu
(2000, 2006, 2007), Brochu et al. (2010), and Brochu and Storrs
(2012), and hereby propose a new generic name for ‘Crocodylus
Institutional AbbreviationsAMNH, American Museum of
Natural History, New York; KNM, National Museums of Kenya,
Nairobi; NHMUK, The Natural History Museum, London.
Anatomical Abbreviationsa, angular; aaf, facet receiving the
astragalus; ace, acetabulum; aip, anterior iliac process; ar,articu-
lar; asr, facet receiving anterior sacral rib; bo, basioccipital; bs,
parabasisphenoid; ch, internal choana; cof, coracoids foramen;
con, condyle; cot, cotyle; cqc, cranioquadrate canal; d,dentary;
d4, dentary tooth position 4; dlc, deltoid crest; Dv, dorsal ver-
tebra; ec, ectopterygoid; emf, external mandibular fenestra; en,
external naris; eo, otoccipital; et3, median Eustachian foramen;
f, frontal; fae, foramen aerum; fm, foramen magnum; fpo, facet
receiving the postorbital; gl, glenoid; h, humerus; hd, femoral
head; if, incisive foramen; ilf, facets receiving the ilium; in,in-
ternal narial fossae; itf, infratemporal fenestra; j, jugal; L, left;
k, keel (on osteoderm); l,lacrimal;lcf, lateral carotid foramen;
leu, lateral Eustachian tube; lo, lateral osteoderm; ls, laterosphe-
noid; m, maxilla; meu, median Eustachian tuber; mg, Meckel’s
groove; mjf, medial jugal foramen; m5, maxillary tooth position
5; n, nasal; nc, neural canal; npr, nasal process; ns, neural spine;
o, orbit; p, parietal; pa, palatine; paf, facet receiving the pubis;
pip, posterior iliac process; pm, premaxilla; pmo, paramedian os-
teoderm; pnr, prenarial rostrum; po, postorbital; pob, postorbital
bar; poz, postzygapophysis; pra, prearticular; prf, prefrontal; pro,
prootic; prz, prezygapophysis; psr, facet receiving the posterior
sacral rib; pt, pterygoid; q, quadrate; qj, quadratojugal; R, right;
sa, surangular; so, supraoccipital; sp, splenial; sq, squamosal; sr,
sacral rib; stf, supratemporal fenestra; sym, mandibular symph-
ysis; V, foramen for trigeminal nerve; vm, ventromedial process;
XII, foramen for hypoglossal nerve; 4th, fourth trochanter of
Nyang Rise is a fossil-bearing area that has been known since
at least 1986 (Pickford, 1986), though not systematically collected
until 2011. The site is located approximately 800 m south from
the tip of Kaswanga Point and approximately 1470 m northwest
of the Tom Mboya Mausoleum. The center of Nyang Rise is ap-
proximately 40 m southeast of Shackleton Gully (e.g., Pickford,
1986), from which the holotype of ‘Crocodyluspigotti was re-
covered (Tchernov and Van Couvering, 1978). It is about 88 m
west-northwest of the locality known as Croc Knob (e.g., Pick-
ford, 1986). Its coordinates are 02423.10S, 34853.93Eandit
has an elevation of approximately 1160 m (Fig. 1).
We recovered several bones and teeth from mammals of
various sizes, including rodents, anthracotheres, rhinoceroses,
chalicotheres, proboscidians, tragulids, and creodonts. Prelim-
inary taphonomic and geologic observations suggest that the
Nyang Rise locality may represent an allochthonous accumula-
tion formed in a slow-moving fluvial environment. Bone surfaces
are well preserved. Local accumulation of multiple partially ar-
ticulated ‘Crocodyluspigotti individuals and several associated
mammals at and around Nyang Rise and Croc Knob suggest ei-
ther a time-averaged accumulation of animals by multiple pro-
cesses or a catastrophic death event. Ongoing taphonomic analy-
sis of the assemblage will assess these processes.
The Hiwegi Formation is dominated by fine-grained vol-
caniclasitic sediments. Whereas some members of the Hiwegi
Formation record thick, stratified deposits of ashes and other
volcanic output, the Fossil Bed Member that produced the
material described here is made up of fluvial deposits and weakly
developed paleosols. Traditionally, the entire Hiwegi Formation
is interpreted as having been deposited at 17.8 Ma (Drake
et al., 1988). However, new research focused on refining the
geochronology of the Miocene strata on Rusinga suggests that
the Fossil Bed Member may be older than 18.0 Ma (Peppe et al.,
Crocodyluspigotti is the only crocodylid known to occur in
the Hiwegi Formation and all of the material described here is of
size and form consistent with the ‘Crocodyluspigotti holotype.
We surface collected Nyang Rise using a grid system. Most of
the surface bone consisted of fragmentary crocodylian remains,
but also included plastron and carapace fragments from a
large tortoise and a single, partial, pythonid snake vertebra.
During surface collection, an in situ set of crocodylid jaws was
discovered. Subsequent investigation of these bones revealed a
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FIGURE 2. Osteolaemus osborni (AMNH R 160900). A, skull and mandible in left lateral view. Skull in B, posterior; C, dorsal; and D, ventral views.
Scale bar equals 50 mm.
multitude of in situ specimens. Most of the material pertains to
several ‘Crocodyluspigotti individuals, but also includes partial
remains of various mammals. Once it was determined that the
locality was densely fossiliferous, we employed archaeological
excavation methodology to recover in situ bone.
The excavation consisted of 8 m2on an aribitrary grid. All
bones larger than 20 mm in length were recorded for position and
orientation with respect to sedimentary context and position, and
excavated sediment was screened through 5, 2, and 0.5 mm mesh
to recover additional fragmentary material and microfauna.
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CROCODYLIA Gmelin, 1789 (sensu Benton and Clark, 1988)
BROCHUCHUS, gen. nov.
Type SpeciesCrocodylus pigotti Tchernov and Van Couver-
ing, 1978.
Included SpeciesBrochuchus pigotti (monospecific).
Etymology—Named in honor of Christopher A. Brochu, for
his tireless and unceasing scientific work on Crocodylia and its
relatives, combined with ‘souchus’ (Greek for crocodile), a com-
mon suffix for crocodylomorph genera. The unusual combina-
tion and spelling are intended as an auditory and visual pun such
that the ‘ch’ sound in Brochu takes the place of the ‘s’ sound in
‘suchus.’ The name is masculine.
BROCHUCHUS PIGOTTI (Tchernov and Van Couvering,
1978) (new combination)
(Figs. 3–10)
Holotype—NHMUK PV R7729 (Tchernov and Van Couver-
ing, 1978).
Previously Referred Material—KNM-RU 2560, left
ulna; KNM-RU 2561, right femur; KNM-RU 2562, right fe-
mur; KNM-RU 2563, right humerus; KNM-RU 2564, right
humerus; KNM-RU 2565, right fibula; KNM-RU 2566, left cora-
coid; KNM-RU 2567–2568, two cervical vertebrae; KNM-RU
2570, dorsal vertebra; KNM-RU 2571, sacral vertebra; KNM-RU
2573, dorsal vertebra; KNM-RU 2574, cervical vertebra; KNM-
RU 2575, frontoparietal; KNM-RU 2576, right jugal; KNM-RU
2577, left ectopterygoid; KNM-RU 2578, basioccipital; KNM-RU
2579, right jugal; KNM-RU 2580, left dentary; KNM-RU 2581,
right surangular; KNM-RU 2582, right dentary; KNM-RU 2583,
right dentary; KNM-RU 2584, right angular; KNM-RU 2596, five
osteoderms; KNM-RU 2597, right maxilla.
Other Previously Collected Material—The partial snout with
dentaries KNM-RU 23819 exists in the collection as Crocodylus
cf. pigotti. Because it comes from Rusinga and because its mor-
phology is consistent with that of other crocodylid material from
Rusinga that has been referred to the species, we consider it a
specimen of Brochuchus pigotti.
New Material—Like the type material, the new material
comes from the Hiwegi Formation of Kaswanga (R5) (Fig. 1).
Specimens newly referred to Brochuchus pigotti are the follow-
ing: KNM-RU 52950, a partial skull (skull table and braincase)
with a partial associated skeleton; KNM-RU 52948, a partial
skull (skull table, partial braincase, quadrates, mandibles) with
associated vertebrae and osteoderms; RU 2011-829, an articu-
lated series of five dorsal vertebrae; RU 2011-1023, an isolated
basioccipital; KNM-RU 52952, a partial skull (jugal, quadrate,
mandible) with associated osteoderms, vertebrae (cervicals,
dorsals, caudals), and appendicular elements; KNM-RU 52953,
a partial skull (quadrate, ectopterygoid, basioccipital, partial
maxilla, partial mandible) with associated femur, tibiae, verte-
brae, and osteoderms; KNM-RU 52954, a partial skull (quadrate
and associated fragments of squamosal and braincase, suran-
gular, articular) with associated vertebrae (including the first
sacral) and osteoderms; KNM-RU 52955, a fragmentary skull
(including basioccipital and maxilla) and associated vertebrae,
osteoderms, and a femur; KNM-RU 52958, an isolated humerus;
KNM-RU 52957, a partial skull (skull table, snout, braincase,
left quadrate, mandible) and associated vertebrae and numerous
Horizon and Distribution—The type material described by
Tchernov and Van Couvering (1978) is from a nearby site; it
FIGURE 3. Photograph of specimens in situ, but after initial excavation at Nyang Rise. Note the mixing of specimens with some anatomical associa-
tion maintained within specimens. Scale bar equals 100 mm.
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comes from “below Marker Bed I, Fossil Bed Member, Hi-
wegi Formation; Shackleton Gully, Kaswanga, Rusinga Island,
South Nyanza, Kenya” (Tchernov and Van Couvering, 1978:858).
Newly collected material (including Figs. 4A, B, E, F, I, J, 5–9)
comes from Nyang Rise. Additional previously collected ma-
terial from KNM, including a jugal (Fig. 4C, D) and an pre-
orbital rostrum (Fig. 4G, H), lack specific locality information
and are attributed to only ‘Rusinga.’ Other, possibly referable,
material comes from Saudi Arabia (Buffetaut, 1984) and Italy
(Kotsakis et al., 2004) (see above). Note that because we have
not examined the material directly, remains from Saudi Arabia
and Italy were not included in the diagnoses, nor the analyses
Revised Diagnosis—Tchernov and Van Couvering (1978) di-
agnosed ‘Crocodyluspigotti on a combination of plesiomorphic
and derived character states. They suggest that it is a “Crocodylus
with fairly flat, low skull, slender at quadratojugal level; moder-
ately long, narrow rostrum due to slight increase in relative length
of premaxillae and maxillae relative to primitive crocodylids such
as Crocodylus megarhinus. Paramedian premaxillary-maxillary
suture extends posteriorly to level of second maxillary tooth.
Facial process of premaxilla extends to level of second maxillary
tooth. Maxillopalatine median suture extends to level between
seventh and eighth maxillary teeth. Palatine fenestra small with
anterior-most margins at level of tenth maxillary tooth. Five
premaxillary and fourteen maxillary teeth; premaxillary notch
for lower canine noticeably constricted; large protuberance
on rostrum immediately posterior to fifth maxillary tooth.
Mandible with fifteen teeth” (Tchernov and Van Couvering,
Brochuchus pigotti is an osteolaemine crocodylid differing
from Osteolaemus in possessing maxillary and dentary teeth that
are circular in cross-section, in possessing a linear medial mar-
gin of the suborbital fenestra, in lacking a strong dorsal margin
of the surangular as part of the glenoid fossa lateral wall, and
in possessing a posterodorsally sloped neural spine on the axis.
Brochuchus pigotti differs from Voay robustus in possessing a
foramen aerum at the extreme medial margin of the retroartic-
ular process, in lacking a discrete squamosal ‘horn,’ and in pos-
sessing a skull table exposure of the supraoccipital. Brochuchus
pigotti differs from Voay robustus and Rimasuchus lloidi in pos-
sessing a transversely linear (rather than an arched) frontopari-
etal suture and in possessing smooth lateral palatine margins.
Brochuchus pigotti differs from Osteolaemus, KNM-RU 23819,
and Voay robustus in exhibiting a supratemporal fenestra, in pos-
sessing an anterior palatine process that extends well beyond the
level of the anterior margin of the suborbital fenestra, in bearing
a narrow supraacetabular crest, and in lacking an anterior process
of the dorsal midline osteoderms. Brochuchus pigotti differs from
Osteolaemus,Euthecodon,Rimasuchus lloidi,andVoay robustus
in possessing a tapered anterior tip of the palatine. The anterior
teeth are elongate and conical, but the posterior-most maxillary
and dentary teeth are much lower and rounder. Brochuchus pig-
otti differs from KNM-RU 23819 in possessing prominent pre-
orbital ridges, a sulcus between the articular and surangular.
Brochuchus pigotti differs from Osteolaemus,Rimasuchus lloidi,
KNM-RU 23819, and Voay robustus in possessing an anteriorly
forked ectopterygoid tip. Brochuchus pigotti differs from Osteo-
laemus, KNM-RU 23819, and Voay robustus in that its palatine
process does not extend significantly beyond the anterior end of
the suborbital fenestra.
Skull Form—We recovered portions of no fewer than 10 skulls
in varying degrees of completeness. The form of these referred
skulls is consistent with that of the holotype specimen (NHMUK
PV R7729) in that the snout is relatively elongate and tapering.
The skull is dorsoventrally very shallow with dorsally facing or-
bits. The preorbital snout makes up approximately two-thirds
the total skull length (from snout tip to posterior margin of the
quadrate) and between 70% and 75% of the craniobasal length
(snout tip to posterior tip of the occipital condyle). The broadest
part of the skull table is approximately 60% the broadest point of
the skull (Fig. 6).
The single, undivided, external naris is broadest anteriorly, be-
ing slightly attenuated posteriorly, but retains a gently curved
transverse posterior margin (Fig. 4A, H, K). Its margins are pri-
marily formed by the premaxillae, with a narrow posterior con-
tribution by the nasals. There is a strong constriction of the snout
just posterior to the level of the last premaxillary tooth and a
notch allowing transmission of the anterior dentary fang (Fig.
4F–H). The elongate suborbital fenestra is rounded anteriorly
and attenuated posteriorly, and lies adjacent to maxillary tooth
positions 10–14. Its margins are formed by the maxilla (anteri-
orly), palatine (medially), and ectopterygoid (laterally), with a
narrow posterior contribution from the pterygoid. The infratem-
poral fenestra (lateral temporal fenestra) is anteriorly attenu-
ated. The supratemporal fenestra is subovoid, with an associ-
ated supratemporal fossa formed primarily by the parietal and
squamosal (Figs. 4I, J, 5A, 6B).
Premaxilla—The premaxillae (Fig. 4A, B, F–H) form the an-
terior and lateral margins of the bony external naris. Each pre-
maxilla possesses a posteriorly attenuated process that extends
beyond the premaxillomaxillary diastema and terminates at ap-
proximately the level of the second maxillary tooth position. The
undivided external naris opens anterodorsally (Fig. 4H). A sub-
triangular incisive foramen, completely housed within the pre-
maxilla, is present and situated well away from the premaxillary
tooth row (Fig. 4A, F). There are five premaxillary teeth.
Maxilla—The holotype preserves 14 maxillary teeth. Similar to
most other crocodylids, but differing from the osteolaemine Eu-
thecodon, the fifth maxillary tooth is the most robust (Fig. 4F,
G). A rounded protuberance is present posterodorsal to the fifth
tooth position on the dorsal surface of the maxilla (Fig. 4H), simi-
lar to that of many crocodylids (e.g., Crocodylus niloticus). Small
occlusal pits are visible between the maxillary teeth anterior to
the level of the suborbital fenestra.
Nasal—The nasals are fused to form a single element. The
nasal is well preserved in the holotype and in the referred speci-
men KNM-RU 23819 (Fig. 4H). No internarial bar is preserved in
either of these specimens. The nasal contributes narrowly to the
narial margin between the dorsomedial expansions of the pre-
maxillae, forming approximately one-third of the posterior bor-
der of the bony external naris. The breadth of the nasal is gen-
erally consistent for most of its length, but tapers anteriorly near
the external naris and posteriorly between the prefrontals.
Jugal—The jugal is a triradiate element with an anterior ra-
mus, a posterior ramus (which forms the anteroventral margin of
the infratemporal fenestra), and a postorbital bar (Fig. 4C, D).
The anterior ramus is flat and laterally overlaps the maxilla. Two
medial jugal foramina are preserved between the posterior mar-
gin of the maxillary facet and the postorbital bar. The latter is
narrow and bears a posteroventrally arched surface with contigu-
ous postorbital and ectopterygoid facets. Posterior to the postor-
bital bar, the zygomatic process is dorsoventrally constricted with
a posteriorly expanded quadratojugal process that tapers more
posteriorly. As in several crocodylids (see, for example, Brochu
et al., 2010; see also Osteolaemus osborni in Fig. 2A, B), the zygo-
matic process is mediolaterally broader than the orbital process.
The posterior ramus of the jugal is separated from the quadrate
by the quadratojugal (Figs. 5A, 6A, C).
Lacrimal—The lacrimal (Fig. 6A, B) is typical of crocodylids
in forming the anterior margin of the orbit and bearing a lacrimal
duct. There are no distinctive crests. Posteriorly, the lacrimal
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FIGURE 4. Skull elements of Brochuchus pigotti. Left premaxilla (KNM-RU 52958) in A, dorsal and B, medial views. Left jugal (KNM-RU 2579)
in C, lateral and D, medial views. E, partial braincase (KNM-RU 52953) in ventral view. F, ventral view of a right, preorbital snout (KNM-RU 52958).
A preorbital snout with mandible (KNM-RU 23819) in G, ventral and H, dorsolateral views. Orbital region and parietal table with a partial braincase
(KNM-RU 52950) in I, dorsal and J, ventral views. K, skull map for the figure in dorsal view, modified after Tchernov and Van Couvering (1978).
Scale bars equal 50 mm (A–D, F–J). Scale bar equals 25 mm (E).
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FIGURE 5. Partial skulls with braincases of Brochuchus pigotti. Skull with braincase, quadrates, and right supratemporal arches (KNM-RU 52958)
in A, ventral and B, posterior views. Braincase with partial parietal (RU 2011-837) in C, right lateral and D, posterior views. Scale bars equal 50 mm
(Aand B)and25mm(Cand D).
narrowly contributes to the orbital margin and broadly contacts
the anterior margin of the jugal.
Prefrontal—The subovoid prefrontal (Figs. 4I, J, 6A, B) con-
tributes narrowly to the orbital margin and invades the space
between the lacrimal and nasal anteriorly. Its exposed anterior
terminus extends to approximately the same level as that of the
Frontal—The frontal (Figs. 4I, J, 6A, B) is subpentagonal with
a narrow intranasal process that contacts the prefrontals and con-
tributes to the orbital margins, and an expanded posterior end
bearing broad postorbital and parietal sutures. The interorbital
surface is flat, with weakly upturned orbital margins. There is no
frontal contribution to the margins of the supratemporal fenes-
trae, and the frontoparietal suture is interdigitating, but trans-
verse. A deep and well-defined olfactory canal is formed by de-
scending processes of the frontal.
Postorbital—Each postorbital (Figs. 4I, J, 6A, B) is a trira-
diate element bearing an anteromedial frontoparietal process,
a posteriorly directed squamosal process, and a subcolumnar
and ventrally directed postorbital bar. The flat dorsal surface
overhangs the postorbital bar. The postorbital contributes to the
anterolateral margin of the supratemporal fenestra, but bears
only a small part of the supratemporal fossae along the frontal
contact. The anterolateral surface of the postorbital is gently
rounded, forming the anterolateral margin of the skull table.
Posterolaterally, the postorbital forms most of the dorsal margin
of the infratemporal fenestra. The frontopostorbital contact is
posteromedially oriented, the narrow parietopostorbital con-
tact is posterolaterally oriented, and the postorbitosquamosal
contact is transversely oriented with a slight posterolateral
Squamosal—The squamosal (Figs. 4I, J, 6A, B) forms the
posterior and posterolateral margins of the supratemporal
fenestra, the posterior margin of the infratemporal fenestra, and
the posterolateral part of the skull table. It bears broad contacts
with the parietal, postorbital, quadratojugal, quadrate, and otoc-
cipital. Along with the postorbital, the squamosal contributes the
entire dorsal margin of the otic aperture. The strongly developed
descending process of the squamosal posterodorsally overlies the
quadrate and laterally overlaps the otoccipital.
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FIGURE 6. Reconstructed skull of Brochuchus pigotti based on the holotype and referred material in A, left lateral; B, dorsal; and C, ventral views.
Nearly the entire skull is known except for the posteroventral parts of the pterygoid, which are shown as semiopaque shadows. Specimen scaled to the
size of relatively large specimens. Scale bar equals 50 mm.
Although some specimens (including the holotype) exhibit a
completely flat posterodorsal margin of the squamosal (Tchernov
and Van Couvering, 1978), others possess a weakly developed
posterodorsal thickening (visible in Figs. 4I, 6A). However, no
available specimen shows a prominent horn-like projection like
that of some crocodylians (see Brochu, 2003, 2007; Brochu et al.,
Parietal—The parietal (Figs. 3, 4I, J, 6B) is of subequal width
anteriorly and posteriorly, but constricted in the middle by the
supratemporal fenestrae and fossae. Anteriorly, the parietal has
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a broad frontal contact and narrow contact with the postorbital
anterolaterally. The contacts with the squamosals are relatively
broad. The frontoparietal contact is transverse, and the poste-
rior margin of the parietal is posteriorly expanded; neither the
otoccipital nor the supraoccipitals projects onto the skull roof
posterior to the parietal. The dorsal surface of the parietal is
Quadratojugal—Lying between the jugal, quadrate, and
squamosal, and forming the posteroventral margin of the lat-
eral temporal fossa, the quadratojugal (Figs. 5, 6) is a flat, sub-
rectangular element that is closely appressed to the dorsolateral
surface of the quadrate. The broad contact with the posterior
part of the jugal is extremely elongate and posteroventrally ori-
ented. The squamosal contact is narrow, and lies mostly lateral to
the broad quadrate-squamosal suture. There is no quadratojugal-
postorbital contact.
Palatine—The palatine has an elongate, anteriorly attenuated
maxillary process that extends to approximately to the level of
the seventh maxillary tooth position. Posterior to the level of
the anterior margin of the suborbital fenestra, and at about the
level of the 10th maxillary tooth, the palatine has a dramatic
expansion such that the posterior part of the maxillopalatine
suture is curved laterally. The interpalatine suture is straight,
and the palatine-pterygoid suture is transverse and occurs at the
posterior-most margin of the suborbital fenestra. There is no in-
vasion of the suborbital fenestra by the palatine like that present
in the osteolaemines Osteolaemus tetraspis and Voay robustus
(Brochu, 2007; Brochu et al., 2010).
Ectopterygoid—The ectopterygoid (Figs. 3, 6A, C) possesses
broad maxillary and pterygoid facets connected by a constricted
body. The long axes of the two facets are oriented at 90rela-
tive to one another. Slightly more than one-half of the maxillary
facet overlaps the level of the posterior end of the maxillary tooth
row. Although the ectopterygoid approaches the maxillary tooth
row, it does not contribute to the margins of any alveoli. The ec-
topterygoid overlies the lateral surface of the pterygoid flange.
The ectopterygoid-pterygoid wing is expansive and extends far
ventrally. Its depth below the level of the jugal bar is approxi-
mately equal to the depth of the skull dorsal to the zygomatic
arch (see Tchernov and Van Couvering, 1978; Fig. 6A).
Pterygoid—The pterygoid (Figs. 4E, 6A, C) broadly contacts
the palatine, ectopterygoid, parabasisphenoid, and basioccipital.
The pterygoid flange is dorsoventrally expansive and anteropos-
teriorly broad. It contributes narrowly to the posterolateral mar-
gin of the suborbital fenestra. The posteroventral (transverse)
margin of the pterygoid flange is one of the few parts of the skull
not represented. The internal choana is undivided, but with a
small median ridge on its posterodorsal margin (Fig. 4E), con-
sistent with the condition seen in Osteolaemus osborni (Fig. 2D).
There is no ‘choanal neck’ sensu Brochu (2007).
Quadrate—The quadrate (Fig. 5) contributes the entire poste-
rior margin of the external otic aperture and lacks any kind of
dermal sculpting or pitting. The quadrate forms part of the lat-
eral braincase wall, contributing the dorsal margins of the trigem-
inal foramina. Posteriorly, the quadrate bears a robust squamosal
ridge on the dorsolateral part of the posterior surface, dorsal
to the level of the foramen aerum. The posterior opening of
the foramen aerum is located near the medial margin of the
quadrate (dorsal to the medial hemicondyle), just dorsal to the
level of the dorsal-most margin of condylar surface (Fig. 5A, B).
A distinct medial hemicondyle is present and is more expanded
than in Osteolaemus (see Fig. 2B, D), but is not as robust as
in some crocodylids (e.g., Crocodylus anthropophagus;Brochu
et al., 2010).
Laterosphenoid and Prootic—Only a few details can be
gleaned from the known parts of the prootic and laterosphenoid
(Fig. 5C, D). The prootic is visible as a small crescent of bone
forming the ventral margins of the primary trigeminal foramen
(for cranial nerve V). The laterosphenoid is conservative in mor-
phology and orientation for a crocodylid (compare with figures
in Holliday and Witmer, 2009). An ovoid foramen pierces the
laterosphenoid just anterodorsal to the primary trigeminal fora-
men, presumably conducting the maxillary branch of the trigemi-
nal based on comparisons with extant taxa (Holliday and Witmer,
Supraoccipital—The supraoccipital (Fig. 5) is pentagonal in
posterior view. The transverse dorsal margin fails to reach the
dorsal surface of the skull, instead being dorsally deep to the pari-
etal. The dorsolateral surfaces are ventrolaterally oriented and
border the small posttemporal fenestrae. The ventrolateral sur-
faces are ventromedially oriented and form an obtuse ventral an-
gle, and are completely overlapped by the dorsal margin of the
otoccipitals. The posterodorsal margin of the supraoccipital bears
a strong dorsal keel.
Otoccipital—The otoccipitals (Fig. 5) form the dorsal and lat-
eral margins of the foramen magnum and the posterior parts of
the paroccipital processes. The foramen magnum is ovoid, be-
ing broader than tall (Fig. 5B, D). The paroccipital processes
are elongate, dorsally arched with ventrolaterally inclined tips,
and with broad quadrate overlaps. Their distal ends possess a
dorsoventrally oriented lateral margin without significant broad-
ening or attenuation.
The otoccipitals meet at the midline, separating the supraoc-
cipital from the foramen magnum. Each otoccipital possesses a
short ventral pedicle that contacts the dorsolateral part of the
kidney-shaped occipital condyle (formed by the basioccipital),
but without significant contribution to the condyle itself. Just lat-
eral to the otoccipital-basioccipital contact, and near the base of
the occipital condyle, the otoccipital is pierced by two foramina
(Fig. 5D) that would have likely carried cranial nerves IX–XI
and the lateral jugular vein (see data in Brochu et al., 2010;
Kley et al., 2010). A small hypoglossal foramen (for cranial nerve
XII) is present on the pedicle of the occipital condyle near the
otoccipital-basioccipital suture. A small lateral carotid foramen
is present ventral to the common cranial nerves IX–XI/jugular
Basioccipital and Parabasisphenoid—The robust basioccipital
(Figs. 4E, 5) forms the occipital condyle posteriorly and extends
anteroventrally to form the posteroventral part of the braincase.
It has a well-developed posteroventral keel.
As mentioned above, the occipital condyle is kidney- or ‘D’-
shaped. We recovered five occipital condyles and all bear this
characteristic shape. This contrasts with the condition seen in
most crocodylids wherein the occipital condyle is often spheri-
cal or ovoid. However, Osteolaemus osborni has a subspherical
occipital condyle with a slightly flattened dorsal (chordal) sur-
face. The occipital condyle of Brochuchus pigotti is very different
from that of the coeval Euthecodon wherein the otoccipitals con-
tribute significantly to the dorsal surface of the condyle and meet
The basioccipital forms the posterior margin of the ovate me-
dian Eustachian foramen, but the parabasisphenoid forms the lat-
eral and anterior margins. The lateral Eustachian foramina are
present just dorsolateral to the median Eustachian foramen.
Dentary—Dentaries are well represented from the new spec-
imens (Figs. 3, 7) as well as previously collected material (e.g.,
Fig. 4G, H). The dentary is generally similar to that of Osteolae-
mus (e.g., Osteolaemus osborni; Fig. 2A). It is of a similar robust-
ness as is present in many crocodylids, but (unsurprisingly) not as
massive as in some larger Crocodylus species (see, for example,
Wagner, 2005; Brochu et al., 2010). There are 15 dentary tooth
positions. The fourth dentary tooth is the largest and its alveolus
is separated from that of the third tooth (Fig. 7A, B).
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FIGURE 7. Mandible of Brochuchus pigotti.A, reconstructed mandible in left lateral view. The full extent of the retroarticular process is uncertain
and it is shown as a semiopaque shadow. B, left dentary (RU 2011-1054) in lateral view. C, left dentary (KNM-RU 52951) in lateral view. D,right
angular (KNM-RU 52950) (reversed) in lateral view. E, symphysial part of a left dentary in medial view (KNM-RU 52951). All scale bars equal 50 mm.
The dentary is somewhat twisted along its long axis such that
the alveoli of the first eight teeth and the last tooth are visible in
lateral view, but those between are not (Fig. 7A, B). A short di-
astema is present between the eighth and ninth tooth positions.
The 10th and 11th teeth are relatively large (Fig. 7C), approach-
ing the size of the fourth tooth. Posterior to the 11th tooth posi-
tion, the teeth become progressively smaller and somewhat less
conical. All alveoli are round (Fig. 3). The mandibular symph-
ysis extends to about, or just beyond, the level of the fifth tooth
position (Figs. 4G, 7E).
Splenial—The splenials do not meet at the midline and do not
contribute to the mandibular symphysis, although they closely ap-
proach it (Fig. 4G). At its anterior end, the splenial is attenuated
and narrow. More posteriorly, it is expanded dorsally and ven-
trally. It extends onto the ventral surface of the mandible at about
the level of dentary tooth 8 or 9. It remains unclear whether the
splenial reached the posterior alveoli in Brochuchus pigotti as it
does in Osteolaemus and some other crocodylids.
Angular—The elongate and ventrally convex angular (Figs. 3,
7A, D) extends from the level of the space between the penulti-
mate and ultimate tooth position to a point just posterior to the
mandibular glenoid. It forms the ventral margin of the external
mandibular fenestra and the ventral margin of the posterior part
of the mandible. The angular possesses a shallow posteroven-
tral fossa, presumably for the insertion of the pterygoideus jaw
adductors. Deep pits cover most of the lateral surface and are
present from a level just anterior to the mandibular glenoid to
near the anterior terminus of the bone, but the pitting is most
strongly developed in the area around and immediately posterior
to the external mandibular fenestra. Posterior to this level and
along the presumed insertion site for the adductor muscles, the
angular lacks pitting. The angular and surangular appear to ex-
tend to approximately the same posterior level (Fig. 3). The ex-
ternal suture between the dentary and angular is ‘V’-shaped with
a small process of the dentary underlying the level of the external
mandibular fenestra, but separated from it by a small flange of
the angular. The surangular-angular contact is a gently ventrally
curved, overlapping suture that extends from the posteroventral
margin of the external mandibular fenestra to the base of the
retroarticular process.
Surangular—The surangular (Figs. 3, 7A) is a long, low bone
forming the dorsal mandibular margin, and most of the dorsal
and the posterior margins of the external mandibular fenestra.
Its anterior contact with the dentary is somewhat sinuous and
forms two anterior processes of unequal length (Fig. 7A).
A posterodorsal process of the dentary narrowly separates
the surangular from the anterodorsal margin of the external
mandibular fenestra. The surangular does not reach the level
of the posterior-most tooth position and terminates anterior to
the level of the anterior tip of the angular. The full extent of
the surangular contribution to the retroarticular process remains
uncertain (Figs. 3, 7A).
Articular—The articular is generally similar to that of other
crocodylids. It possesses an anterior lamina dorsal to the medial
foramen, and the lingual foramen occurs on the laterally bowed
angular-surangular suture. There is no sulcus between the articu-
lar and surangular. The foramen aerum occurs at the lingual mar-
gin of the base of the retroarticular process.
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FIGURE 8. Selected postcrania of Brochuchus pigotti.A, dorsal vertebra (KNM-RU 52958) in left, lateral view. First sacral vertebra (KNM-RU
52958) in B, posterior and C, anteroventral views. D, partial posterior caudal vertebra (KNM-RU 52952) in lateral view. E, right scapula and coracoid
(KNM-RU 52954) in right lateral view. F, right scapula (KNM-RU 52950) in medial view. G, partial humerus (KNM-RU 52950) in dorsal view. Right
ilium (KNM-RU 52948) in H, lateral and I, medial views. J, right ischium (KNM-RU 52950) in ventrolateral view. K, right femur (KNM-RU 52950)
in ventral view. L, partial tibia (KNM-RU 52958), lacking ends, in ventral view. Scale bar equals 50 mm.
Addition of this new material means that most of the skeleton
is now known (Figs. 3, 8–10). Among the appendicular elements,
only the radius, pubis, fibula, and autopodia remain relatively un-
known or are known from very incomplete remains. Likewise,
most of the vertebral column is represented, but little is known
of the caudal vertebrae. Dermal armor is present in abundance
(Fig. 9).
Vertebrae—The vertebrae are procoelous and robust with tall
neural spines. Vertebrae were the second-most numerous type of
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FIGURE 9. Brochuchus pigotti osteoderms. A, right anterolateral
nuchal shield osteoderm (KNM-RU 52951). B, lateral nuchal osteoderm
(KNM-RU 52958). C, section of dorsal shield (KNM-RU 52954). Para-
median and right lateral section. All in approximate dorsal view. Scale
bar equals 50 mm.
element recovered with the new specimens, the first being osteo-
derms. Many centra lacking their neural arches were recovered,
suggesting the presence of juvenile specimens. Even so, those
specimens are subequal or similar in size to specimens retaining
fused neural arches and, thus, likely represent late subadults. The
first sacral vertebra (Fig. 8B, C) displays a robust and distally ex-
panded sacral rib. The condyles and cotyles are nearly circular
and the smallest diameter of the neural canal is approximately
50% of the diameter of the articulating cotyle. Little of the caudal
series is known. One distal caudal vertebra seems to demonstrate
that the caudal centra were similar in length to the centra of the
presacral vertebrae.
Pectoral Girdle and Forelimb—The scapulae and coracoids
are represented by the new material (Fig. 8E, F). The dorsal
blade of the scapula is slender in that it is approximately three-
fifths the breadth of the scapular body. The blade expands slightly
dorsally. Its deltoid crest is expressed as an anterolateral ridge
that runs posterodorsally. The glenoid is broad and expanded.
The coracoid is subequal in length to the scapula. It possesses a
massive glenoid expansion at the glenoid fossa and a somewhat
constricted neck with some anteromedial expansion (Fig. 8F).
The humerus (Fig. 8G) is relatively slender compared with that
of many Crocodylus. Numerous ulnae are known, but they are
not significantly different from those of other crocodylians in be-
ing elongate and slightly curved with expanded ends.
Pelvic Girdle and Hind Limb—Among the newly recovered
material is an incomplete ilium (Fig. 8H, I) lacking the dorsal part
of its posterior iliac process. The ilium bears almost the entire ac-
etabulum. Unfortunately, because of the damage to the posterior
iliac process, it is unclear whether Brochuchus pigotti possessed a
constriction of that process (‘wasp waisting’ sensu Brochu, 2007).
The anterior iliac process is robust but rounded, and is about one-
half the length of the posterior process. The supraacetabular crest
is narrow, as it is in other osteolaemines. A right ischium is pre-
served with KNM-RU 52950 (Fig. 8J). Although the anterior iliac
process and distal blade are damaged, the ilum is otherwise com-
plete and shows a typical crocodylid morphology in possessing a
posterodorsal spur and ventromedial, blade-like flange.
The femur (Fig. 8K) is somewhat sigmoidally curved. In con-
trast to the relatively slender humerus, the femur is robust, with
similar relative proportions to that of the very robust osteolaem-
ine Voay robustus (Brochu, 2007). Although not as robust as in
Voay robustus, the fourth trochanter of Brochuchus pigotti is well
developed and raised. The tibia is similarly robust, but rather
shorter than the femur (Fig. 8K, L).
Numerous osteoderms were recovered with the new specimens
(e.g., Fig. 9) and are also present with specimens at KNM. All
of the known osteoderms possess some keeling, although some
possess a more prominently defined keel (Fig. 9B) than others
(Fig. 9A). Many of the osteoderms are nearly square (Fig. 9C),
although some, presumably those from the nuchal region, are
rounded and with a robust keel (Fig. 9B), whereas others describe
an irregular pentagon and possess only a faint ridge (Fig. 9A).
The latter may represent part of a nuchal shield similar to that
found in modern Osteolaemus wherein four large osteoderms are
found near the junction of the neck and shoulder region. The os-
teoderm illustrated in Figure 9A possesses an articular/sutural
surface anteriorly and anterolaterally, and may have repre-
sented the posterolateral osteoderm in such a posterior nuchal
A section of the dorsal shield was recovered in articulation, or
nearly so, with four pairs of paramedian osteoderms (Fig. 9C) re-
maining in contact with each other. Three lateral osteoderms are
preserved nearly in articulation, demonstrating well-developed
keels on the latter, but not the former.
Data Matrix
We modified the morphological phylogenetic data matrix of
Brochu and Storrs (2012), which itself is the latest iteration of
the crocodylian data matrices published by Brochu (1997, 1999)
that has been consistently modified and expanded over the last
dozen years or so (e.g., Buscalioni et al., 2001; Brochu, 2006, 2007;
Brochu et al., 2010). The Brochu and Storrs (2012) matrix in-
cludes only Crocodylidae and its pertinent outgroups, making it
appropriate for the current study.
Based on our observations, we made changes and additions to
the scores of Brochuchus pigotti from the scores of Brochu and
Storrs (2012), where it was included as ‘Crocodyluspigotti.These
changes reflect updates to the previous scores based mainly on
the inclusion of our new material.
New material reveals that the anterior half of the axis neural
spine slopes anteriorly (character 11, state 1) rather than being
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FIGURE 10. Reconstructed skeleton of Brochuchus pigotti based on available specimens with interpretive body silhouette. Reconstruction scaled to
approximately 1800 mm total length. Scale bar equals 100 mm.
oriented horizontally. The posterior half of the axis neural spine
(previously unknown) is narrow (character 13, state 1). Deep
pits are absent from the cervical and anterior dorsal vertebrae
(character 20, state 0; previously unknown). The scapular blade
displays minimal flaring at maturity (character 23, state 1) and
a thin deltoid crest with a sharp margin (character 24, state 0).
Information from the ilium, the first recovered, demonstrates
that it has a very small anterior iliac process (character 33, state
1) and that the supraacetabular crest is broad (character 35,
state 1). The limb bones are relatively robust, with hind limbs
being longer than forelimbs at maturity (character 36, state 0).
Paramedian osteoderms are nearly square, rather than rectan-
gular (character 39, state 1), and without any apparent dorsal
midline process on the anterior margin (character 43, state 1).
The angular-surangular suture contacts the extrernal mandibular
fenestra at the posterior angle (character 60, state 0) and the
surangular-dentary suture intersects said fenestra anterior to
the posterodorsal corner (character 64, state 0). The anterior
processes of the surangular are unequal (character 61, state 0).
The foramen aerum of Brochuchus pigotti occurs at the lingual
margin of the retroarticular process (character 70, state 0) as it
does in extant Osteolaemus, but not in the osteolaemine Voay
robustus. The articular lies flat against the surangular (character
74, state 1). As with other crocodylids, the incisive foramen is
placed at the level of the premaxillary tooth row (character 89,
state 1). The medial process of the prefrontal pillar is expanded
anteroposteriorly (character 109, state 1). The maxilla bears a
posterior process that partly invades the contact between the
lacrimal and nasal (character 128, state 1). The lacrimal is longer
than the prefrontal (character 130, state 0). No contact is present
between the postorbital and quadrate or the quadratojugal
(character 143, state 0) and the quadrate contributes to the in-
fratemporal fenestra (character 145, state 1). Our new specimens
demonstrate the absence of a supraoccipital exposure on the
dorsal skull table (Figs. 4I, 5D). The quadrate-pterygoid suture
is linear from the parabasisphenoid exposure to the trigemi-
nal foramen (character 168, state 1). The parabasisphenoid is
broadly exposed ventral to the basioccipital (character 173, state
0). More than two-thirds of the lateral margin of the suborbital
fenestra is formed by the ectopyterygoid (character 185, state 1).
We added scores for three terminal units not included in ear-
lier versions of this data matrix. These additional species and
specimens are KNM-LT 24081 (an unnamed crocodylid from
the Lothagam site [Miocene–Pliocene], near Lake Turkana) (Fig.
11A, B) and the Kanapoi Crocodylus niloticus’ (three specimens
from the Kanapoi site [Pliocene] near Lake Turkana).
Consequently, the phylogenetic data matrix for the current
analysis includes the 189 morphological characters provided by
Brochu et al. (2010) and 55 terminal units (see Appendix 1 for
new character scores).
Analysis and Results
We used NEXUS Data Editor (NDE) (Page, 2001) to assem-
ble and manage the data matrix. We performed an analysis us-
ing the New Technology Search in the computer program T.N.T.
(Goloboff et al., 2003) (1000 replicates) with ‘ratchet’ and ‘drift’
options employed. The shortest tree length recovered by the
analysis was 322 steps, with a consistency index, excluding unin-
formative characters, of 0.4219, and a retention index of 0.7143.
The analysis found 776 trees of that length and none shorter.
Tree Topology—The results of our analysis generally match
those of Brochu and Storrs (2012). The analysis of Brochu and
Storrs (2012) differed from that of Brochu et al. (2010) in that the
Osteolaeminae of the latter analysis lacked strong support in the
former. Brochu et al. (2010) found support for a clade containing
gariepensis and another containing Osteolaemus,Voay robustus,
and Rimasuchus lloydi. Some of the principal trees recovered
by the Brochu and Storrs (2012) analysis recover a close rela-
tionship between Mecistops,Brochuchus pigotti,and‘Crocody-
Analysis of our modified version of the Brochu and Storrs
(2012) analysis resolves the interrelationships of Osteolaeminae
sensu Brochu et al. (2010) as a paraphyletic assemblage of two
clades lying just outside of Crocodylus (Fig. 12). The more basal
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FIGURE 11. Comparative skull material of crocodylids included in this study. A, orbital region and parietal table of KNM-LT 24081 in dorsal view.
B, left mandible of KNM-LT 24081 in lateral view. C, orbital region and parietal table of Euthecodon brumpti (KNM-LT 23177) in dorsal view. D,
orbital region and parietal table of Crocodylus niloticus (AMNH R 127255) in dorsal view. Both scale bars equal 50 mm.
of these two clades consists of Osteolaemus,Voay robustus,Ri-
masuchus lloydi, KNM-LT 24081, and Brochuchus pigotti.We
will, hereafter, informally refer to this clade as ‘osteolaemins.’
The second clade, here recovered as the sister group to Crocody-
lus, consists of Mecistops cataphractus,‘Crocodylusgariepensis,
and the two included species of Euthecodon. Hereafter, we will
informally refer to this clade as ‘mecistopins.’
Here we offer the character support for some selected clades
from our analysis. Character numbers and states follow Brochu
and Storrs (2012).
The clade containing osteolaemins, mecistopins, and Crocody-
lus is supported by three unambiguous synapomorphies:
(1) Square/subsquare midline dorsal osteoderms (character 39,
state 1).
(2) Surangular does not reach the dorsal tip of the lateral glenoid
wall (character 67, state 1).
(3) The jugal forms the posterior angle of the infratemporal fen-
estra (character 142, state 1).
Mecistopins are united with Crocodylus to the exclusion of os-
teolaemins by three unambiguous synapomorphies:
(1) Ilium with strong dorsal indentation (character 34, state 2)
(unknown in Brochuchus pigotti).
(2) Angular-surangular sutures passes broadly along the ventral
margin of the external mandibular fenestra (character 60,
state 1).
(3) Iris is greenish/yellowish in color (character 182, state 0)
(rather than brown; unknown in Brochuchus pigotti).
Mecistopins are united to the exclusion of other taxa based on
two unambiguous synapomorphies:
(1) Lingual surangular spur bordering the denatary tooth row for
at least one alveolus length (character 62, state 0) (unknown
in Brochuchus pigotti).
(2) Nasals excluded, at least externally, from the naris; nasals
and premaxillae still in contact (character 82, state 2).
Osteolaemins are united to the exclusion of all other taxa by
four unambiguous synapomorphies:
(1) Ilium with a broad supraacetabular crest (character 35,
state 1).
(2) Prominent preorbital ridges (character 97, state 1).
(3) Pterygoid surface lateral and anterior to the internal choana
pushed inward anterolateral to the choanal aperture (charac-
ter 123, state 1).
(4) Squamosal extends ventrolaterally to the lateral extent of the
paroccipital process (character 159, state 1).
Rimasuchus lloydi, KNM-LT 24081, and Brochuchus pigotti
are united to the exclusion of Voay robustus and Osteolaemus
by the shared presence of a maxillary invasion of the lacrimal-
nasal contact (character 128, state 1). A sister-group relation-
ship is recovered between KNM-LT 24081 and Brochuchus
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FIGURE 12. Adams and strict consensus of
776 trees generated by the current analysis.
Topology is from the Adams consensus and the
asterisk () indicates the only node recovered
by the Adams consensus, not present in the
strict consensus. Each of the shortest trees had a
length of 322 steps, a consistency index, exclud-
ing uninformative characters, of 0.4219, and a
retention index of 0.7143. The data matrix is
that of Brochu and Storrs (2012) with addition
of new/revised data for Brochuchus pigotti and
the new inclusion of the Kanapoi Crocodylus
niloticus,’ and KNM-LT 24081.
pigotti. This relationship is supported by three unambiguous
(1) Palatine process forms a thin wedge anteriorly (character
116, state 1).
(2) Frontoparietal suture transverse (character 151, state 1).
(3) No supraoccipital exposure on the dorsal skull table (charac-
ter 160, state 1).
Noteworthy within this analysis is the placement of some spec-
imens that have traditionally been assigned to Crocodylus niloti-
cus from the Kanapoi site (see above; the ‘Kanapoi Crocodylus
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niloticus” in Fig. 12). Our analysis suggests that the taxon rep-
resented by these specimens is actually more closely related to
the fossil taxon Crocodylus palaeindicus. The Kanapoi Crocody-
lus niloticus’andCrocodylus palaeindicus are united here based
on two unambiguous synapomorphies:
(1) Palatine-pterygoid suture nearly at the posterior angle of the
suborbital fenestra (character 118, state 0).
(2) Supraoccipital lacking exposure on the dorsal skull table
(character 160, state 1).
The Kanapoi Crocodylus niloticus’ differs from extant
Crocodylus niloticus in the two character states listed above and
in possessing no posterior process of the maxilla (character 128,
state 0). Even so, the position of Crocodylus niloticus within
Crocodylus is volatile. In 71 of the 776 principal trees recovered
(approximately nine percent), Crocodylus niloticus is the sister
group to the clade containing the Kanapoi Crocodylus niloticus
and Crocodylus palaeindicus. However, it is recovered in many
different phylogenetic placements across the various principal
Rusinga Island fossils preserve an important snapshot of the
East African early Miocene. Rusinga is most famous for its rich
mammalian fossil record and particularly for its many primate
species, including two species of Proconsul (Le Gros Clark, 1950;
Andrews, 1974; Andrews and Simons, 1977; Walker et al., 1993;
Lehmann, 2009; Peppe et al., 2009; and chapters in Werdelin and
Sanders, 2010). In addition to the mammalian taxa, Rusinga Is-
land also includes a diversity of reptile fossils that are impor-
tant for understanding African paleoecology and biogeography.
Moreover, the Rusinga reptile record includes taxa that offer in-
sights into the evolutionary and phylogenetic history of clades
such as Chamaeleonidae (Hillenius, 1978; Rieppel et al., 1992)
and Varanidae (Clos, 1995), as well as Crocodylia.
Brochuchus pigotti has been somewhat problematic over the
history of its study. It was originally compared to, and consid-
ered a close relative of, Crocodylus niloticus (Tchernov and Van
Couvering, 1978). Cladistic analyses (e.g., Brochu, 2007; Brochu
et al., 2010) later showed Brochuchus pigotti to be an osteolaem-
ine crocodylid rather than a Crocodylus. The most recent phylo-
genetic treatment of Crocodylidae failed to find support for Os-
teolaeminae sensu Brochu et al. (2010) and did not resolve the
relationships of a clade consisting of Brochuchus pigotti,Euthe-
codon,and‘Crocodylusgariepensis, another consisting of Oste-
olaemus,Voay robustus,andRimsasuchus lloydi with respect to
Crocodylus (Brochu and Storrs, 2012).
Membership of ‘Osteolaeminae’ as recovered in some recent
analyses (e.g., Brochu et al., 2010) included a range of variation
similar to that of Crocodylidae as a whole. This amount of mor-
phological variation within so small a clade would be remarkable.
The most recent analysis (Brochu and Storrs, 2012) recovered
those ‘osteolaemines’ as a polytomy, but with a large range of
variation represented by the giant longirostrine Euthecodon and
the more generalized and smaller Brochuchus pigotti.
Our analysis resolves the polytomy from Brochu and Storrs
(2012), finding Brochuchus pigotti to be closely related to Oste-
olaemus rather than Euthecodon. Indeed, our analysis recovers
an osteolaemin clade whose members possess skull morphologies
with moderately elongate snouts similar to the extant generalist
Osteolaemus, and a mecistopin clade (including Euthecodon)that
shows a tendency toward elongate snouts and dentition similar to
that of the more piscivorous Mecistops cataphractus.
However, as noted by Brochu (2007), there are genetic data
suggesting a close relationship between Mecistops cataphractus
and Osteolaemus (White and Densmore, 2001; Gatesy et al.,
2003; Schmitz et al., 2003; McAlily et al., 2006), and the relation-
ships of our ‘osteolaemins’ and ‘mecistopins’ should be further
Two extant species of Osteolaemus are all that remain of Os-
teolaeminae, and these species are colloquially known as ‘dwarf
crocodiles.’ Brochuchus pigotti, KNM-LT 24081, and Voay ro-
bustus (Brochu, 2007) represent somewhat larger osteolaemins,
but they are still relatively small as compared with most known
crocodylians. By contrast, Rimasuchus lloydi often reached very
large sizes, with skulls exceeding 0.8 m in craniobasal length, sug-
gesting an animal that commonly exceeded five meters in total
Brochuchus pigotti is an osteolaemine crocodylid, not closely
related to Crocodylus; as such, it deserves generic distinctive-
ness. Although Brochuchus pigotti was relatively small for a
crocodylid, it was larger than the extant Osteoleamus and had
morphology characteristic of a generalist crocodylian predator in
possessing a relatively long and broad, if dorsoventrally shallow,
skull. The postcranial skeleton reveals a general robustness that
is similar to that of other ‘osteolaemines’ (Brochu, 2007; Brochu
et al., 2010). The new remains add significantly to our under-
standing of this species and help to clarify osteolaemine interrela-
tionships, resolving polytomous relationships recovered by a re-
cent phylogenetic analysis (Brochu and Storrs, 2012) and demon-
strating the paraphyly of ‘Osteolaeminae’ as presented by some
other recent studies (Brochu, 2007; Brochu et al., 2010), break-
ing it into two smaller clades just outside of Crocodylus.The
basal of the two groups shows a more generalist snout and den-
tal morphology (Osteolaemus,Brochuchus pigotti,Rimasuchus
lloydi, and the unnamed taxon represented by KNM-LT 24081).
The other clade, the sister group to Crocodylus, is a longirostrine
clade (Euthecodon,Mecistops cataphractus,and‘Crocodylus
Numerous large-bodied mammals and presumably semi-
aquatic monitor lizards coexisted with Brochuchus pigotti, sup-
porting the hypothesis of a riverine environment. Although too
small to be any threat to proboscideans or other large Hiwegi
mammals, Brochuchus pigotti may have been able to take smaller
mammals such as the anthropoid Proconsul, offering the possi-
bility that crocodiles were anthropoidophagous long before the
appearance of Crocodylus anthropophagus.
We are grateful to P. O’Connor, J. Sertich, and an anony-
mous reviewer for their comments and assistance in improving
the manuscript. Field work was conducted with the permission
and support of the Kenyan Government and National Museums
of Kenya, and funded through grants from the National Science
Foundataion (0852609 and 0852515) and the McKnight Founda-
tion, University of Minnesota. We thank E. Mbua, B. Onyango,
and the curational staff at the Kenya National Museum for their
project support. We are also grateful for research, equipment,
and logistics support from the British Institute in East Africa,
and to C. Tryon, S. Driese, L. Michel, C. Mesjef, and D. Nelson.
M. Laird provided special and invaluable assistance with speci-
men care. M. Flagg assisted with photography. This research was
only possible through the gracious and vital support from the
people of Rusinga Island, especially S. Onyango (Chief, Rusinga
West), A. Wandango, S. Okayo, the staff and management of
the Rusinga Island Lodge, and the outstanding excavators from
Kaswanga. Specimen access was graciously provided and facil-
itated by D. Frost, D. Kizirian, D. Dickey, and R. Pascocello
(AMNH, Herpetology) and C. Mehling and C. Osmone (AMNH,
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APPENDIX 1. Taxon by character matrix. Here, we include
scores for the new data described in our paper. These charac-
ters are scored based on the data matrix of Brochu and Storrs
(2012) and are meant to be added to it. We replaced codings for
Crocodylus pigotti with Brochuchus pigotti and added Crocody-
lus cf. niloticus and KNM-LT 24081. The matrix is presented
in NDE (Page, 2001), PAUP(Swofford, 2001), and T.N.T.
(Goloboff et al., 2003, 2008) friendly format, without special
alignment or character numbers. Thus, it may be cut-and-pasted
directly from the pdf.
?????????? ?????????? ?????????? ??????????
??????1100 2????????1 ?1???????? 1???????0?
110?000010 0210000100 ???0000??? ?000000010
10?????000 0?111110?0 ?101110012 001??10101
??11???1?? 1?????0000 3?????00?
Brochuchus pigotti
?????????? 101010?000 111001111? ??1?10?11?
??1???1110 2??1?????0 0?20??1110 ??11????00
010?010010 0210001100 01000001?? ?001010110
1010001100 00111110?? ?1011?0012 1010010111
0??1?1?111 0001000000 3???1000?
KNM-LT 24081
?????????? ?????????? ?????????? ???????11?
??0??????0 ?????????0 0?20??1??0 ?110????0?
?????????? ??????0??? ????????0? ?00011??10
?????????? ??111?1??? ??????0??2 10????0?11
?0?1?????? ????0????? ????100??
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... Euthecodon (Buffetaut, 1979;Tchernov & Couvering, 1978) and gharials referred by Storrs (2003) to Eogavialis Buffetaut, 1982 (Figure 1h) have been reported from sites near Lake Victoria and Lake Turkana, but otherwise, the crocodylian faunas appear to have been very different from those at higher stratigraphic levels. The only crocodylian not sporting a tubelike snout thus far reported from this interval is the small osteolaemine Brochuchus Conrad et al., 2013 (Figure 1d), which is unrelated to any generalized crocodylid found later in the Neogene and may not have exceeded 2.5 m in total length (Conrad et al., 2013;Cossette et al., 2020;Tchernov & Couvering, 1978). Nothing ecologically equivalent to large Crocodylus has previously been reported. ...
... Hekkala et al. (2021) used the morphological data set of Lee and Yates (2018), who also recovered a Euthecodon-Mecistops grouping. Lee and Yates (2018) relied on Conrad et al. (2013) for data on Brochuchus, and our scores for Brochuchus (as well as other crocodylians) differ in several ways (Cossette et al., 2020). Support for a Brochuchus-Euthecodon relationship in our combined analysis was comparatively low (posterior probability value of .6141), ...
... This would have been inconsistent with the presence of occlusal pits between most alveoli, and there may no longer have been sufficient space for the additional alveoli seen in other crocodylids. In this sense, Kinyang is the opposite of Brochuchus, in which maxillary alveoli and teeth are comparatively small and widely spaced (Conrad et al., 2013;Cossette et al., 2020). ...
Full-text available
We describe two new osteolaemine crocodylids from the Early and early Middle Miocene of Kenya: Kinyang mabokoensis tax. nov. (Maboko, 15 Ma) and Kinyang tchernovi tax. nov. (Karungu and Loperot, 18 Ma). Additional material referable to Kinyang is known from Chianda and Moruorot. The skull was broad and dorsoventrally deep, and the genus can be diagnosed based on the combined presence of a partial overbite, a subdivided fossa for the lateral collateral ligament on the surangular, and a maxilla with no more than 13 alveoli. Phylogenetic analyses based on morphological and combined morphological and molecular data support a referral of Kinyang to Osteolaeminae, and morphological data alone put the new taxon at the base of Euthecodontini. Some Kinyang maxillae preserve blind pits on the medial caviconchal recess wall. Kinyang co-occurs with the osteolaemine Brochuchus at some localities, and together, they reinforce the phylogenetic disparity between early Neogene osteolaemine-dominated faunas and faunas dominated by crocodylines beginning in the Late Miocene in the Kenya Rift. The causes of this turnover remain unclear, though changes in prevailing vegetation resulting from tectonic and climatic drivers may provide a partial explanation.
... Whereas the consensus of recent molecular phylogenies places Mecistops as the sister taxon to Osteolaeminae (Schmitz et al., 2003;McAliley et al., 2006;Man et al., 2011;Oaks, 2011;Shirley et al., 2014;Pan et al., 2021), our topology is consistent with previous morphological analyses (e.g. Brochu et al., 2010;Conrad et al., 2013;Brochu, 2020) that recover Mecistops as closer to Crocodylus, and thus part of Crocodylinae. ...
... Osteolaemines first appear in the fossil record later than Crocodylinae, with the stratigraphically oldest occurrences known from the early Miocene of north and east Africa (Brochu, 2000(Brochu, , 2007aConrad et al., 2013;, represented by the earliest diverging taxa Euthecodon arambourgi (Ginsburg & Buffetaut, 1978) and Brochuchus (Tchernov & Van Couvering, 1978;Conrad et al., 2013; (Fig. 36). The clade remained endemic to Africa (Brochu, 2007a), including the early-middle Miocene taxon Rimasuchus lloydi (Fourtau, 1920;Joleaud, 1920;Storrs, 2003;Brochu, 2020). ...
... Osteolaemines first appear in the fossil record later than Crocodylinae, with the stratigraphically oldest occurrences known from the early Miocene of north and east Africa (Brochu, 2000(Brochu, , 2007aConrad et al., 2013;, represented by the earliest diverging taxa Euthecodon arambourgi (Ginsburg & Buffetaut, 1978) and Brochuchus (Tchernov & Van Couvering, 1978;Conrad et al., 2013; (Fig. 36). The clade remained endemic to Africa (Brochu, 2007a), including the early-middle Miocene taxon Rimasuchus lloydi (Fourtau, 1920;Joleaud, 1920;Storrs, 2003;Brochu, 2020). ...
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First appearing in the latest Cretaceous, Crocodylia is a clade of semi-aquatic, predatory reptiles, defined by the last common ancestor of extant alligators, caimans, crocodiles, and gharials. Despite large strides in resolving crocodylian interrelationships over the last three decades, several outstanding problems persist in crocodylian systematics. Most notably, there has been persistent discordance between morphological and molecular datasets surrounding the affinities of the extant gharials, Gavialis gangeticus and Tomistoma schlegelii . Whereas molecular data consistently support a sister taxon relationship, in which they are more closely related to crocodylids than to alligatorids, morphological data indicate that Gavialis is the sister taxon to all other extant crocodylians. Here we present a new morphological dataset for Crocodylia based on a critical reappraisal of published crocodylian character data matrices and extensive firsthand observations of a global sample of crocodylians. This comprises the most taxonomically comprehensive crocodylian dataset to date (144 OTUs scored for 330 characters) and includes a new, illustrated character list with modifications to the construction and scoring of characters, and 46 novel characters. Under a maximum parsimony framework, our analyses robustly recover Gavialis as more closely related to Tomistoma than to other extant crocodylians for the first time based on morphology alone. This result is recovered regardless of the weighting strategy and treatment of quantitative characters. However, analyses using continuous characters and extended implied weighting (with high k -values) produced the most resolved, well-supported, and stratigraphically congruent topologies overall. Resolution of the gharial problem reveals that: (1) several gavialoids lack plesiomorphic features that formerly drew them towards the stem of Crocodylia; and (2) more widespread similarities occur between species traditionally divided into tomistomines and gavialoids, with these interpreted here as homology rather than homoplasy. There remains significant temporal incongruence regarding the inferred divergence timing of the extant gharials, indicating that several putative gavialids (‘thoracosaurs’) are incorrectly placed and require future re-appraisal. New alligatoroid interrelationships include: (1) support for a North American origin of Caimaninae in the latest Cretaceous; (2) the recovery of the early Paleogene South American taxon Eocaiman as a ‘basal’ alligatoroid; and (3) the paraphyly of the Cenozoic European taxon Diplocynodon . Among crocodyloids, notable results include modifications to the taxonomic content of Mekosuchinae, including biogeographic affinities of this clade with latest Cretaceous–early Paleogene Asian crocodyloids. In light of our new results, we provide a comprehensive review of the evolutionary and biogeographic history of Crocodylia, which included multiple instances of transoceanic and continental dispersal.
... Based on this evidence, Brochu erected a new monotypic genus, Voay (the modern Malagasy word for extant crocodiles) within Osteolaeminae, resulting in the current species name Voay robustus 33 . Subsequent phylogenetic analyses of morphology [34][35][36][37][38][39] as well as total evidence analyses of morphology and molecules 37,[39][40][41] have consistently clustered V. robustus and Osteolaemus to the exclusion of other crocodylian genera, with Crocodylus distantly related to Voay (Fig. 2). ...
... Crocodylidae groups with Gavialidae (true and false gavials), and this combined clade is sister to Alligatoridae (alligators and caimans). However, our mt trees contradict previous numerical phylogenetic analyses of morphology and combined data that robustly cluster Voay with osteolaemines ( Fig. 2 [33][34][35][36][37][38][39][40][41]44 ). Our mtDNA trees instead reflect a closer association with Crocodylus as hypothesized by earlier authors 29,30,32,45 (Fig. 3). ...
... This labile binary character shows minimally 11 changes on the overall tree (consistency index = 0.091). [33][34][35][36][37][38][39][40][41]44 ). For Crocodylia, prior molecular phylogenetic work suggested that morphological features are commonly characterized by high levels of homoplasy 40,47,48 that may be driven by convergent ecological and functional pressures [49][50][51][52][53][54][55][56][57] . ...
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Ancient DNA is transforming our ability to reconstruct historical patterns and mechanisms shaping modern diversity and distributions. In particular, molecular data from extinct Holocene island faunas have revealed surprising biogeographic scenarios. Here, we recovered partial mitochondrial (mt) genomes for 1300–1400 year old specimens (n = 2) of the extinct “horned” crocodile, Voay robustus, collected from Holocene deposits in southwestern Madagascar. Phylogenetic analyses of partial mt genomes and tip-dated timetrees based on molecular, fossil, and stratigraphic data favor a sister group relationship between Voay and Crocodylus (true crocodiles). These well supported trees conflict with recent morphological systematic work that has consistently placed Voay within Osteolaeminae (dwarf crocodiles and kin) and provide evidence for likely homoplasy in crocodylian cranial anatomy and snout shape. The close relationship between Voay and Crocodylus lends additional context for understanding the biogeographic origins of these genera and refines competing hypotheses for the recent extinction of Voay from Madagascar.
... Extinct relatives of Osteolaemus from the late Cenozoic of Africa and Madagascar represent a much wider range of body size, skull morphology, and (presumably) ecological preference. Some were gharial-like forms with tubular snouts, and others superficially resembled modern generalized crocodylians (sensu Brochu, 2001) such as Crocodylus Laurenti, 1768, bearing moderately long, broad snouts (Brochu, 2000a(Brochu, , 2007Storrs, 2003;Llinás Agrasar, 2004;Brochu and Storrs, 2012;Conrad et al., 2013). Indeed, most such generalized forms were previously referred to Crocodylus (e.g., Fourtau, 1918;Tchernov and Van Couvering, 1978;Tchernov, 1986;Pickford, 2003). ...
... The African sharp-nosed crocodile, Mecistops Gray, 1844, is also an osteolaemine in some analyses (e.g., lineage not currently found east of Lake Tanganyika or south of the Congo Basin (Shirley et al., 2018). But osteolaemines are known from the early Miocene of Egypt, Libya, Namibia, and Kenya (Fourtau, 1918;Tchernov and Van Couvering, 1978;Brochu, 2000a;Pickford, 2003;Llinás Agrasar, 2004;Brochu and Storrs, 2012;Conrad et al., 2013). Indeed, the only generalized crocodiles known from Africa during the early Miocene are putative osteolaemines. ...
... In the EARS, the generalized osteolaemine Brochuchus pigotti (Tchernov and Van Couvering, 1978) and its tube-snouted close relative, Euthecodon Fourtau, 1920, have been reported from the ca. 18 Ma Hiwegi Formation on Rusinga Island and correlative units in the Lake Victoria region of Kenya (Tchernov and Van Couvering, 1978;Buffetaut, 1979;Tchernov, 1986;Conrad et al., 2013). By ca. ...
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Brochuchus is a small crocodylid originally based on specimens from the early Miocene of Rusinga Island, Lake Victoria, Kenya. Here, we report occurrences of Brochuchus from several early and middle Miocene sites. Some are from the Lake Victoria region, and others are in the Lake Turkana Basin. Specimens from the middle Miocene Maboko locality form the basis of a new species, Brochuchus parvidens , which has comparatively smaller maxillary alveoli. Because of the smaller alveoli, the teeth appear to be more widely spaced in the new species. We also provide a revised diagnosis for Brochuchus and its type species, B . pigotti . A phylogenetic analysis supports a close relationship between Brochuchus and tube-snouted Euthecodon , but although relationships among crocodylids appear poorly resolved in the set of optimal trees, this is because Brochuchus and Euthecodon , along with early Miocene “ Crocodylus ” gariepensis from the early Miocene of Namibia, jointly adopt two distinct positions—either closely related to the living sharp-nosed crocodile ( Mecistops ) or to a group including the living dwarf crocodiles ( Osteolaemus ). Character support for a close relationship with Mecistops is problematic, and we suspect a closer relationship to Osteolaemus will be recovered with improved sampling, but the results here are ambiguous. In either case, Brochuchus is more closely related to living groups not currently found in East Africa. This material helps constrain the timing of crocodylian faunal turnover in the East African Rift Valley System, with endemic lineages largely being replaced by Crocodylus in the middle or late Miocene possibly in response to regional xerification and the replacement of continuous rainforest cover with open grasslands and savannas. UUID:
... Similarly, the absence of the cranial process in the cranial margin of the dorsal midline of the osteoderms cannot be checked in Duerosuchus, but it can be observed in Boverisuchus vorax. The osteoderms of Bernissartia fagesii, non-crocodylian eusuchians, gavialoids, Borealosuchus, Tsoabichi greenriverensis and Brochuchus pigotti present a broad convexity along their cranial margins, corresponding with the cranial articular surface (Brochu, 1999(Brochu, , 2010Conrad et al., 2013). This convexity is absent in the osteoderms of Boverisuchus vorax and a number of crocodyloids (Brochu, 1999(Brochu, , 2013. ...
Duerosuchus piscator is a middle Eocene eusuchian known only from Corrales del Vino (Zamora, Spain). The species was defined based on an incomplete skull, partial lower jaws and two vertebrae from a single individual, and several osteoderms referred to other specimens. A detailed study of these remains allows us to question the attribution of all these remains to the same form. Just the cranial remains are considered as indisputably attributable to it; the validity of this species being supported. The present study provides a detailed description and an amended diagnosis for Duerosuchus piscator, which is included for the first time in a phylogenetic analysis in order to establish its systematic position within Crocodylia. As a result of this study, the Eocene crocodyliform paleobiodiversity in the Duero Basin is recognized as comprising a notosuchian (Iberosuchus macrodon), as well as three crocodylians, each belonging to a clade: the alligatoroid Diplocynodon tormis, a crocodyloid traditionally attributed to the genus Asiatosuchus, and Duerosuchus piscator, which is here identified as a planocraniid, up to now unrecognized in the Iberian fossil record.
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The Miocene is a key time in the evolution of African mammals and their ecosystems witnessing the origin of the African apes and the isolation of eastern coastal forests through an expanding biogeographic arid corridor. Until recently, however, Miocene sites from the southeastern regions of the continent were unknown. Here we report discovery of the first Miocene fossil teeth from the shoulders of the Urema Rift in Gorongosa National Park, Mozambique, at the southern East African Rift System. We provide the first 1) radiometric age determinations of the fossiliferous Mazamba Formation, 2) reconstructions of past vegetation in the region based on pedogenic carbonates and fossil wood, and 3) description of fossil teeth from the southern rift. Gorongosa is unique in the East African Rift System in combining marine invertebrates, marine vertebrates, terrestrial mammals, and fossil woods in coastal paleoenvironments. The Gorongosa fossil sites offer the first evidence of persistent woodlands and forests on the coastal margins of southeastern Africa during the Miocene, and an exceptional assemblage of fossil vertebrates including new species. Further work will allow the testing of hypotheses positing the formation of a northeast-southwest arid corridor isolating species on the eastern coastal forests from those elsewhere in Africa. Brief The Miocene is a key time in the evolution of African mammals and their ecosystems encompassing hominine origins and the establishment of an arid corridor that isolated eastern Africa’s coastal forests. Until now, however, Miocene sites from southeastern Africa have been unknown. We report the discovery of the first Miocene fossil sites from Gorongosa National Park, Mozambique, and show that these sites formed in coastal settings. We provide radiometric ages for the fossiliferous sediments, reconstructions of past vegetation based on stable isotopes and fossil wood, and a description of the first fossil teeth from the region. Gorongosa is the only paleontological site in the East African Rift that combines fossil woods, marine invertebrates, marine vertebrates, and terrestrial mammals. Gorongosa offers the first evidence of persistent woodlands and forests on the coastal margins of southeastern Africa during the Miocene.
To explore shape variability among crocodylian skull tables, an analysis using geometric morphometric methods is conducted with the inclusion of extant and fossil taxa. Skull tables are variable and the differences likely play a role in hydrodynamics, species recognition, and biomechanical adaptations. Comparisons of allometric change within taxa are explored revealing that adults significantly diverge from juvenile skull table morphologies in most species and these changes happen in a stereotyped way. In all analyses, adults of the smallest extant taxa plot alongside the juveniles of related taxa and heterochrony may explain the maintenance of these morphologies into adulthood. When landmarks representing the supratemporal fenestrae are included, longirostrine taxa are broadly separated from one another due to variation in the size of the supratemporal fenestrae. The hypotheses of previous studies suggesting that the size of the supratemporal fenestrae is influenced by snout length—with longer snouts corresponding to larger fenestrae—must be re‐evaluated. Although species of the crocodyloids Tomistoma and Euthecodon approach or exceed the length of the snout in gavialoids, their supratemporal fenestrae are proportionally smaller—this suggests a phylogenetic constraint in crocodyloids regardless of snout length.
The lower Miocene of Rusinga Island (Lake Victoria, Kenya) is best known for its vertebrate fossil assemblage but the multiple stratigraphic intervals with well-preserved fossil leaves have received much less attention. The Hiwegi Formation has three fossil leaf-rich intervals, which span the entire formation from oldest to youngest: Kiahera Hill, R5, and R3. Here, we describe new fossil collections from Kiahera Hill and R3 and compared these floras to previous work from R5, as well as modern African floras. The oldest flora at Kiahera Hill was most similar to modern tropical rainforests or tropical seasonal forests and reconstructed as a warm and wet, closed forest. This was followed by a relatively dry and open environment at R5, which was reconstructed as a woodland to open tropical seasonal forest. The youngest flora at R3 was most similar to modern tropical seasonal forests and was reconstructed as a warm and wet spatially heterogenous forest. Floral composition of all three floras differed, but the Kiahera Hill and R3 floras were more similar to each other than either flora was to the R5 flora. The Kiahera Hill flora had few monocots or herbaceous taxa, was dominated by large leaves, and had higher species richness and greater evenness than the R3 flora. Our work, coupled with previous studies, suggests that the R3 landscape consisted of both closed forest areas and open areas with seasonal ponding. The absence of morphotypes from the R5 flora that were present in the Kiahera Hill and R3 floras provides evidence for local extirpation during the R5 time interval. Thus, this work indicates that the Hiwegi Formation on Rusinga Island samples multiple environments ranging from more closed tropical forests to more open woodlands in the Early Miocene and provides important context for the evolution and habitat preference of early apes.
The known fossil record of crocodyliforms in Europe during the Paleogene is significantly biased, in that the fauna of Western Europe is far better sampled and understood compared to that of Eastern Europe. We describe in detail all known crocodyliform remains from the middle Eocene (Lutetian) Ikovo locality in Ukraine. We conclude that at least two taxa were present: a moderate to large-sized Tomistominae indet. similar to the basalmost known tomistomines, and the small-sized basal alligatoroid cf. Diplocynodon sp. Despite its scarcity, this is the first basal alligatoroid material reported from Eastern Europe (as part of post-Soviet countries) and the easternmost record of diplocynodontines in Europe so far. An allegedly freshwater cf. Diplocynodon sp. contributes a rare faunal element to the vertebrate assemblage of the Ikovo locality, otherwise dominated by resident or facultative marine taxa. The fossil record and historical paleobiogeography of crocodyliforms from the Paleocene and Eocene of Europe are reviewed. As it has been already known, the middle Eocene fauna of crocodyliforms proves to be taxonomically diverse and complex. Its constituent lineages geographically originated in Asia or North America (Diplocynodontinae, Asiatosuchus-like crocodyloids, Planocraniidae), North America (derived alligatorines), Africa (Tomistominae), and Gondwana (ziphodont mesoeucrocodylians Iberosuchus and Bergisuchus), with possible subsequent speciation in Europe. We propose a novel hypothesis of Asian origins of European diplocynodontines, which will be explicitly tested in future studies. The revealed similarities between crocodylians and turtles from the Ikovo locality and those from Western Europe support the presence of a single Pan-European biogeographical zone during the middle Eocene, distinct from that of Asia.
We used morphometric data from 1276 Crocodylus moreletii captured in northern Belize (1992- 2001) to develop predictive models for determining body size (total length [TL], snout-vent length [SVL])from measurements of single attributes (dorsal cranial length [DCL], cranial width [CW], snout length [SL] and width [SW], body mass [BM], rear-foot length [RFL]), quantify sexual size dimorphism, examine ontogenetic changes in cranial morphology, re-evaluate maximum body size attained by this species, and estimate standing crop biomass of crocodiles at our principal study site. Strong positive allometric relationships were found between measures of body length and other morphometric attributes, and provide a reliable means to estimate body length from tracks, skulls, and body parts. The maximum DCL:CW ratio is attained at a relatively small body size and preceded a dietary shift from insects and arachnids to vertebrates and ampullarid snails. The SL:SW ratio of C. moreletii is highly variable and because of overlap with C. acutus, deemed of little value for distinguishing these two sympatric species. Both overall and adult sex ratio (female:male) was male biased and differed significantly from parity. The mean SVL of adult males (98.3 ± 21.3 cm) was significantly greater than that of adult females (87.3 ± 15.9 cm). A compressed sexual size dimorphism index (SDI) of 2.12 was calculated for C. moreletii in northern Belize. Based on skull measurements, the current size record for C. moreletii in Belize is 362 cm TL. Standing crop biomass of C. moreletii at our principal study site (Gold Button Lagoon) was estimated to be 9.5 kg/ha.
The longest male and female alligators (Alligator mississippiensis) measured in Florida during 1977-1993 were 426.9 cm and 309.9 cm total length. The heaviest male and female alligators weighed 473.1 and 129.3 kg. A predictive model for calculating total length from head length is presented. Estimated total lengths for three large alligators described in the literature were substantially shorter than reported lengths. The longest alligator for which a total length can be corroborated from skull measurements was 454 cm. We discuss the plausibility of past reports of exceptionally large alligators with respect to verified lengths of specimens, harvest pressure, growth patterns, and longevity.