Drumheller and Brochu | 1
1 PHYLOGENETIC TAPHONOMY: A STATISTICAL AND PHYLOGENETIC
2 APPROACH FOR EXPLORING TAPHONOMIC PATTERNS IN THE FOSSIL
3 RECORD USING CROCODYLIANS
4 STEPHANIE K. DRUMHELLER1, CHRISTOPHER A. BROCHU2
5 1. Department of Earth and Planetary Sciences, The University of Tennessee, Knoxville,
6 Tennessee, 37996, U.S.A.
7 2. Department of Earth and Environmental Sciences, The University of Iowa, Iowa City, Iowa,
8 52242, U.S.A.
9 email: [email protected]
10 RRH: CROCODYLIAN BITE MARKS IN PHYLOGENETIC CONTEXT
11 LRH: DRUMHELLER AND BROCHU Drumheller and Brochu | 2
13 Actualistic observations form the basis of many taphonomic studies in paleontology.
14However, surveys limited by environment or taxon may not be applicable far beyond the bounds
15of the initial observations. Even when multiple studies exploring the potential variety within a
16taphonomic process exist, quantitative methods for comparing these datasets in order to identify
17larger scale patterns have been understudied. This research uses modern bite marks collected
18from 21 of the 23 generally recognized species of extant Crocodylia to explore statistical and
19phylogenetic methods of synthesizing taphonomic datasets. Bite marks were identified, and
20specimens were then coded for presence or absence of different mark morphotypes. Attempts to
21find statistical correlation between trace types, marking animal vital statistics, and sample
22collection protocol were unsuccessful. Mapping bite mark character states on a eusuchian
23phylogeny successfully predicted the presence of known diagnostic, bisected marks in extinct
24taxa. Predictions for clades that may have created multiple subscores, striated marks, and
25extensive crushing were also generated. Inclusion of fossil bite marks which have been positively
26associated with extinct species allow this method to be projected beyond the crown group. The
27results of this study indicate that phylogenies can and should be further explored for use as
28predictive tools in a taphonomic framework.
30 Bite marks represent direct evidence of diet, feeding behavior (e.g., Davidson and
31Soloman 1990; Forrest 2003; Fuentes 2003), and even inter- or intraspecific fighting (e.g.,
32Buffetaut 1983; Williamson 1996; Avilla et al. 2004; Katsura 2004) in the fossil record. These
33bone surface modifications exist at an intersection of ichnology and taphonomy, in which tooth
34shape and structure, jaw morphology and mechanics, and behavior act in concert to create Drumheller and Brochu | 3
35patterns of modification, accumulation, and destruction of remains. Patterns of modern bite
36marks are often observed in order to identify novel traces that could be used for identification
37and interpretation of similar structures in the fossil record (e.g., Njau and Blumenschine 2006;
38Milan et al. 2010; Westaway et al. 2011; Baquedano et al. 2012; Drumheller and Brochu 2014).
39However, sampling of modern bite marks has been uneven across and within clades, and many
40studies focus on a small number of modern groups, sometimes even a single species, to make
41predictions about diverse, extinct clades or morphologies. Drawing such broad conclusions based
42on analyses with strongly restricted study parameters may well be masking patterns of natural
43variation (Lyman, 1994; Haglund and Sorg, 1997).
44 For example, domestic dogs (Canis familiaris) and wolves (e.g., Canis lupus, Canis
45rufus) have an extensive bite mark literature (e.g., Binford 1981; Haynes 1982; Haglund 1997a)
46reflecting their common interaction with forensic sites, importance to studies of early
47domestication, and habit of caching and heavily modifying bones. Among mammals, hyenas
48(e.g., Haynes 1983; Cruz-Uribe 1991; Marean and Spencer 1991), great cats (e.g., Brain 1981;
49Haynes 1983; Domínguez-Rodrigo 1999), bears (e.g., Haynes 1982; Domínguez-Rodrigo and
50Piqueras 2003), and rodents (e.g., Brain 1981; Haglund 1997b; Klippel and Synstelien 2007)
51have also received a substantial amount of attention from bite mark researchers. At the other end
52of the spectrum, bite marks from only one squamate, the Komodo dragon (Varanus
53komodoensis), have been systematically studied, and this dataset stands as the sole modern
54datapoint for comparison with a diversity of ziphodont predators (D’Amore and Blumenschine
56 When multiple surveys within a clade do exist, it is unclear how the results should be
57synthesized, introducing a large degree of uncertainty into interpretations of ancient bite marks Drumheller and Brochu | 4
58based on comparisons to modern ones. Moreover, differing collection protocols and research
59methodologies can hinder statistical comparisons between these datasets. Researchers frequently
60fall back on simply comparing and contrasting their results (Haynes 1983; Drumheller and
61Brochu 2014). However, if a uniform collection protocol could be applied across multiple
62groups, more rigorous ways to explore patterns across the sampled taxa would become available.
63 Here, we present the results of an actualistic survey of bite marks collected from 21
64species of extant Crocodylia. Recent studies have expanded our existing knowledge of the bone
65surface modifications this clade can generate, including potentially diagnostic traces (Njau and
66Blumenschine 2006; Milan et al. 2010; Westaway et al. 2011; Baquedano et al. 2012;
67Drumheller and Brochu 2014). The fossil record of bite marks generated by crocodylians and
68their more distant relatives also has garnered increased attention and study (Davidson and
69Soloman 1990; Carpenter and Lindsey 1980; Erickson 1984; Schwimmer 2002, 2010; Forrest
702003; Fuentes 2003; Cisneros 2005; Mikulás et al. 2006; Martin 2013). In addition to serving as
71important predators and taphonomic agents in their own rights (Noto et al. 2012; Boyd et al.
722013), crocodylians are popular proxies for several extinct clades, including a variety of other
73archosaur-line reptiles (Brazaitis and Watanabe 2011; Drumheller et al. 2014). Therefore a better
74understanding of their feeding behaviors and resulting traces has broad potential for application
75to a large number of paleoecological and paleobiological questions.
76 We further explore patterns of feeding trace expression across this collection of
77crocodylian bite marks with associated metadata representing details characterizing each animal
78and collection methodology used during specimen collection. This allows statistical tests of
79significance between presence or absence of mark types and variables such as age, sex, specimen
80type, and collection protocol. The possibility that phylogeny could inform taphonomic patterns is Drumheller and Brochu | 5
81explored by applying a modified version of the extant phylogenetic bracket method (Witmer
821995). This study will serve not only as a survey of bite marks expected among crocodylians and
83their more distant relatives, but also as a case study demonstrating how future datasets
84addressing a variety of taphonomic and behavioral questions might be collected and synthesized.
85 MATERIALS AND METHODS
86 Bite Mark Collection and Preparation
87 Partially butchered cow hind limbs and pig femora were obtained from meat packaging
89Cow specimens retained significant amounts of flesh at the joints, and included articulated
90femora, tibiae, patellae, and varying numbers of tarsals depending on how much of the foot was
91removed during the butchering processes. Pig femora experienced more initial processing and
92were largely defleshed.
93 Bite marks were collected from 65 individuals, representing juveniles to very large
94adults, from 21 of the 23 generally recognized extant crocodylian species, excluding Gavialis
95gangeticus and Crocodylus palustris (Supplementary Table 1). Bite marks were collected from
96isolated individuals, so that veterinary data kept by SAAF staff could be correlated to specific
97samples (Fig. 1). Smaller animals were presented with isolated pig femora, and larger animals
98were given partially butchered cow hind limbs. Samples usually were collected once voluntarily
99abandoned, although some animals had to be distracted by handlers to prompt sample
100abandonment once active biting ceased. Animals were unrestrained while bite mark samples
101were collected, except when the SAAF staff felt that handler and animal safety was a concern. In
102those cases, often related to the small size relative to bone samples or the aggressive nature of the
103individuals, animals were held near the base of the skull by a handler or, with larger animals, Drumheller and Brochu | 6
104secured by the handler sitting on the back of the animal. Specific feeding behaviors, such as axial
105rolling or violent lateral thrashing, were recorded. Collection protocol and vital statistics (sex,
106mass, age, total length, snout-vent length, cranial length, and whether each animals was born in
107captivity or in the wild, restrained or free during specimen collection, and whether presented
108with cow limbs or pig femora) were recorded for each animal and are presented in
109Supplementary Table 1.
110 After collection, samples were defleshed and degreased via simmering in water with
111Borax®, an enzymatic detergent. After rinsing and manual removal of any remaining soft tissue,
112bones were cleaned again with Luminox® and Dawn®, milder, non-enzymatic detergents.
113Sponges and soft plastic brushes were used to prevent further bone surface modifications during
114the cleaning process. Enzymatic detergents have proven to be highly successful at cleaning bone
115when long-term curation is not an end goal (e.g., Fenton et. al. 2003; Mairs and Rutty 2004;
116Steadman et. al. 2006). Since these samples were destined for further destructive preparation,
117efforts to prevent continued, long-term digestion of the bone by the active enzymes were not
118made (Shelton and Buckley 1990).
119 Bite Mark Identification and Classification
120 Bite marks, as well as butchering traces, were identified using the criteria described by
121Blumenschine et al. (1996). Classification was modeled after Binford (1981) wherein all marks
122are separated into four broad groupings: pits, punctures, scores, and furrows. Pits represent
123depressions on the surface of a bone caused when a tooth tip indents, but does not fully pierce,
124the cortical bone. When piercing does occur, the mark is instead classified as a puncture. When
125the tip of the tooth drags along the surface of the bone, leaving a crushed groove that does not
126fully pierce the cortical bone, the mark is called a score. When a similar bite does pierce the Drumheller and Brochu | 7
127cortical bone, the mark is classified as a furrow (Fig. 2).
128 These broad categories of bite marks can be further divided by any novel mark
129morphology or pattern of expression. In the case of crocodylians, Njau and Blumenschine (2006)
130identified two new types of bite marks in their diagnosis of Crocodylus niloticus feeding traces:
131bisected marks and hook scores. Bisected marks were pits, punctures, and scores (furrows were
132not identified in this study) that exhibited subscoring and/or notching on bite margins. These
133structures were formed by the prominent carinae present on relatively unworn, recently erupted
134crocodylian teeth. Hook scores were defined as J- or L-shaped marks, created when the trajectory
135of a single tooth abruptly changed directions during a biting event. Such marks were tentatively
136associated with death rolling behavior. Hook scores were later identified among modern
137Komodo dragons (Varanis komodoensis) and non-avian theropods (D’Amore and Blumenschine
1382009), suggesting they are not diagnostic of crocodylians or death rolling. Bisected marks,
139however, appear unique to crocodylians and non-crocodylian crocodyliforms (Drumheller 2007;
140Rivera-Sylva et al. 2009; Brochu et al. 2010; Noto et al. 2012; Boyd et al. 2013; Botfalvai et al.,
1412014; Drumheller and Brochu 2014).
142 Secondary alterations related to impact trauma, such as depressed fractures, which occur
143when the margins of a bite mark collapse irregularly under the force of the impacting tooth, can
144also occur. Bone may also fracture radially away from the location of the impact, a secondary
145alteration called fracture lines. Spiral or green stick fractures occur when a bite is powerful
146enough to completely break the bone; these fractures typically propagate in a spiral fashion
147around the circumference of long bones (Byers 2005; Wescott 2013). It should be noted that such
148alterations can be associated with any kind of impact trauma, and are not unique to biting events.
149 Bite marks were photographed in detail with an Olympus® Stylus™ 760 still-image Drumheller and Brochu | 8
150camera. Blind inter-analyst tests have shown that bite marks can be differentiated from other
151types of bone surface modifications using only a 10X hand lens for magnification (Blumenschine
152et al. 1996). However, the presence or absence of bisected marks has been specifically related to
153the relative wear and chipping of the carinae of teeth, with different tooth morphologies and
154levels of wear present within the mouth of a single individual (Njau and Blumenschine 2006).
155Therefore, observing marks under higher magnification could reveal more subtle bisections
156caused by incompletely worn carinae. After light photography, specimens were sectioned into
157pieces (<10 cm maximum length) and imaged on a Hitachi® S-3400N variable pressure
158scanning electron microscope (VP-SEM).
159 Statistical Analyses of Vital Variables and Collection Protocols
160 Once identified, correlation between the presence or absence of novel types of bite marks
161(i.e., subscores) and vital statistics of the animals and collection protocols was tested using either
162a one-way ANOVA (Fisher, 1925) or a chi-squared test of independence (Pearson, 1900). The
163ANOVA works from the null hypothesis that samples from the tested groups (mark type
164presence vs. absence) were drawn from the same underlying population, and is appropriate for
165analyses involving continuous, measured variables (i.e., age, total length, head length, snout-vent
166length, and mass), assuming that sampling is random, variables are independent, and population
167variances are equal. This is a parametric test, and while it is robust to violations of the
168assumption that the tested variables are normally distributed when sample sizes are large, further,
169nonparametric testing, in the form of a Kruskal-Wallis one-way analysis of variance (Kruskal-
170Wallis 1952), was performed as well. The chi-squared test of independence (also called
171Pearson’s chi-squared test) is used to assess whether binary, categorical variables (i.e., sampled
172bone type, collection protocol, sex, origin, and snout ectomorph tested against mark Drumheller and Brochu | 9
173presence/absence) are independent of one another, assuming random sampling, variable
174independence, and a large sample size (these data are near the lower bound). These tests were
175performed with the PAST statistical software package (Hammer et al. 2001), along with that
176software’s standard assumption tests, including Levene’s (1960) and Shapiro-Wilk (1965), and
177were used to determine whether these variables might be affecting the observed patterns of bite
178marks. All data used in these analyses are presented in Supplementary Table 1.
179 Phylogenetic Analysis and Character Mapping
180 Bite mark morphology represents a combination of morphological and behavioral traits
181and may retain a phylogenetic signal. Dental characters, while often highly conserved across
182major crocodylian clades, do retain a phylogenetic signal (Brochu et al., 2012; Brochu, 2013). It
183is unclear how hybrid behavioral and morphological characters, such as bite marks, may be used
184in phylogenetic analyses, because behavioral traits are inherently more labile than morphological
185or molecular characters and, in principle, are secondary expressions of underlying morphology
186and ecology. Moreover, whether learned behavior can be treated as a heritable feature subject to
187homology assessment is an open question (e.g., Wenzel, 1992; de Quieroz and Wimberger 1993;
188Blomberg et al. 2003).
189 However, in at least some cases behavioral characters exhibit analytical rates of
190homoplasy not statistically different from those generated from morphological datasets (de
191Quieroz and Wimberger 1993), and metrics that measure phylogenetic signal have found utility
192even in demonstrably labile behavioral datasets (Blomberg et al. 2003). Whether used as prima
193facie evidence in phylogenetic inference or not, various methods, including parsimony
194optimization, have been applied to study the evolution of behavioral characters in a phylogenetic
195context (e.g., Tullberg et al., 2002; Agnarsson et al, 2006; Paterson et al., 2014; Odom et al., Drumheller and Brochu | 10
1962015). One such method, the extant phylogenetic bracket (Witmer, 1995), is especially useful
197when fossil taxa for which soft-tissue, physiological, life-history, and behavioral features are
198generally not directly preserved. If we assume that such features shared by living species were
199inherited from their last common ancestor, we would predict their presence in extinct members
200of the group descended from that ancestor. In this specific case, bite mark expression as a
201reflection of tooth morphology can be viewed as a Type I inference (i.e., rooted in the presence
202of a preserved osteological correlate), while mark morphology as it relates to behavior is Type II
203(i.e., directly observed in extant sister taxa, but not the outgroup), using the confidence hierarchy
204established for the extant phylogenetic bracket (Witmer, 1995).
205 In order to explore whether phylogeny might be useful when synthesizing bite mark
206datasets, single (bisections) and multiple (trisections or quadrisections) subscores within
207individual bite marks from extant taxa were coded as binary characters (i.e., presence/absence)
208and mapped onto an existing eusuchian phylogeny. The tree used in this analysis was assembled
209from previous maximum parsimony analyses using matrices based on 189 morphological
210characters. Relationships within Crocodyloidea are based on Brochu and Storrs (2012).
211Relationships within other crocodylian clades are based on Brochu et al. (2012) and Brochu
212(2013), and relationships among non-crocodylian eusuchians are based on Narváez et al.
213(2015). Although they used slightly different taxon samples, relationships supported by all of
214these analyses are consistent with each other. Clades supported by one of the trees were added
215manually to the other. The complete consensus tree, with all 124 ingroup taxa, is available in the
216Supplementary Materials as Figure 1.
217 Character state changes for the bite mark characters, as well as other dental characters of
218interest from the original matrix, were mapped onto the strict consensus tree in Mesquite 2.75 Drumheller and Brochu | 11
219(Maddison and Maddison 2011) using the parsimony parameter. Patterns of unambiguous bite
220mark character state changes are interpreted to be phylogenetic predictions of presence or
221absence in the fossil record. Areas of the tree where character states were determined to be
222ambiguous by the parsimony analysis are considered to predict an equal possibility of mark
223presence or absence in the fossil record. These predictions provide a conservative estimate of
224bite mark character distribution within Eusuchia, and we test their accuracy by comparing the
225character states suggested by the extant taxa in the parsimony analysis to published examples of
226crocodylian bite marks ascribed to extinct species.
228 Bite Mark Identification and Classification
229 Presence or absence of particular bite mark types within each sampled taxon is reported
230in Table 1. Scores are present in every sampled taxon, and pits are identified in all but two,
231Paleosuchus palpebrosus and Paleosuchus trigonatus. Punctures were less common, and were
232most often correlated with the physically largest animals sampled (Alligator mississippiensis,
233Crocodylus acutus, Crocodylus porosus, Tomistoma schlegelii). One particularly aggressive, but
234smaller, male A. sinensis (SAAF 86052) deviated from this generalization, and created definite
235punctures on the pig femur presented to him. Punctures were not found in specimens collected
236from Crocodylus niloticus in this survey, but a previous study reported punctures created by
237members of the species (Njau and Blumenschine 2006). Furrows were identified, if only in two
238taxa: Alligator mississippiensis and Crocodylus novaeguineae. As with the punctures, this type
239of mark was caused by particularly large, aggressive animals. Both punctures and furrows were
240most often present at the proximal or distal ends of long bone elements, where the bone itself is
241structurally less dense. While frequency and distribution of these mark types have been used to Drumheller and Brochu | 12
242differentiate groups in larger scale studies of individual species (e.g., Drumheller and Brochu
2432014; Njau and Blumenschine 2006), these marks have been found across multiple vertebrate
244groups (Binford 1981) and therefore, in isolation, are not considered diagnostic of crocodylians.
246cataphractus, Crocodylus intermedius, Crocodylus porosus, Crocodylus siamensis, Osteolaemus
247tetraspis, and Paleosuchus palpebrosus (Fig. 3). However, a previous survey of Crocodylus
248porosus bite marks tentatively reported at least one bisected mark (Westaway et al. 2011). A
249larger scale study of Crocodylus niloticus found that bisected marks represent 10% of marks
250occurring on 82.5% of all marked bones (Njau and Blumenschine 2006), with similar
251percentages being recorded in Alligator mississippiensis as well (Drumheller and Brochu 2014).
252Without a broader survey of the clade to determine regularity of bisected marks, the presence or
253absence of bisections in Crocodylus porosus is considered to be ambiguous for this study.
254 Multiple subscores were present in a smaller number of taxa, and were only identifiable
255under higher magnification. Two subscores, forming a trisection, were identified in Caiman
256yacare and Tomistoma schlegelii. Three subscores, forming a quadrisection, were found in
257Alligator sinensis, Crocodylus johnsoni, Crocodylus novaeguineae, and Osteolaemus tetraspis
259 Crushing associated with the biting event was visible under a hand lens, but distinctly
260obvious under the VP-SEM. Further secondary alterations – depressed fractures, fracture lines,
261and spiral fractures (sensu Byers 2005; Wescott 2013) – were most often associated with high-
262force structures such as punctures on long bone shafts. Spiral fractures were only present in
263samples taken from Alligator mississippiensis (Fig. 4), but bone breakage, often related to limb
264loss, has been reported in forensic case studies involving Alligator mississippiensis, Crocodylus Drumheller and Brochu | 13
265acutus, Crocodylus niloticus, and Crocodylus porosus (Harding and Wolf 2006; Wood 2008;
266Sartain and Steele 2009; Mendieta and Duarte 2009; Cupal-Magaña et al. 2010; Chattopadhyay
267et al. 2013). Spiral fractures previously have been reported in samples taken from a survey of
268Crocodylus niloticus (Njau and Blumenschine 2006) and in forensic case studies involving
269Crocodylus acutus (Cupal-Magaña et al. 2010) and Crocodylus porosus (Wood 2008;
270Chattopadhyay et al. 2013). All fractures found in this study had pits or punctures associated
271with the margins of the break.
272 One unusual mark was found on a sample taken from C. novaeguineae: an irregular
273series of closely spaced scores. The marks were shallower, and more V-shaped in cross section
274than normal bite marks. The animal from which this sample was collected broke a tooth during
275bite mark collection, suggesting that this mark may reflect the jagged edges of a recently snapped
276tooth crown (Fig. 4D).
277 Statistical Analyses of Vital Statistics and Collection Protocols
278 None of the recorded variables associated with animal vital statistics or collection
279protocols were found to correlate significantly with the presence or absence of novel, diagnostic
280traces (i.e., subscores). Numbers of observed subscores were not tested separately, because
281multiple subscores were extremely rare (two individuals left trisections, four left quadrisections),
282and it is probable that they represent marks left by pathological teeth (see discussion below). The
283detailed results of these analyses are presented in Table 2.
284 Phylogenetic Analysis and Character Mapping
285 Within Crocodyloidea, the presence or absence of bisected marks was found to be
286ambiguous in ten fossil taxa – Crocodylus megarhinus, Crocodylus gariepensis, Australosuchus
287clarkae, Kambara implexidens, Trilophosuchus rackhami, Quinkana spp, Rimasuchus lloydi, Drumheller and Brochu | 14
288Euthecodon arambourgii, Euthecodon brumpti, Brochuchus pigotti, Voay robustus – and modern
289Osteolaemus osborni. All remaining fossil taxa are unambiguously predicted to have been
290capable of creating bisected marks, though the absence of samples from Gavialis gangeticus
291does limit the confidence placed on predictions made regarding more basal members of the
292crown group, as they fall outside of the bracketed taxa (Fig. 5).
293 Multiple subscores were predicted to be unambiguously absent across the majority of the
294tree, except within Osteolaeminae and Tomistominae. Tomistoma schlegelii and Osteolaemus
295tetraspis did create multiple subscores in the modern survey. Within Tomistominae, the
296following thirteen fossil species were found to be ambiguous with regards to this character state:
297Tomistoma lusitanica, Toyotamaphimeia machikanensis, Gavialosuchus eggenburgensis,
298Tomistoma petrolica, Paratomistoma courti, Penghusuchus pani, Thecachampsa americana,
299Thecachampsa antiqua, Thecachampsa carolinense, Tomistoma cairense, Megadontosuchus
300arduini, Dollosuchoides densmorei, and Kentisuchus spenceri. Among the osteolaemines,
301Osteolaemus osborni and Voay robustus were also found to be ambiguous (Fig. 6).
302 Other character states mapped in order to explore potential bite mark types included
303features related to feeding strategies and tooth morphologies no longer exhibited by extant
304crocodylians. For example, Quinkana and all members of Planocraniidae have laterally
305compressed teeth (Brochu and Storrs 2012; Brochu et al. 2012; Brochu 2013), with Quinkana
306and Boverisuchus further exhibiting serrated dentition (Brochu and Storrs 2012; Brochu et al.
3072012; Brochu 2013), and therefore, true ziphodonty (Fig. 7). The members of these clades would
308therefore be expected to create marks more similar to those made by other ziphodont groups,
309such as varanids and theropod dinosaurs (D’Amore and Blumenschine 2009).
311increase in diameter posteriorly in the tooth row (Brochu and Storrs 2012; Brochu et al. 2012),
312including some species that have extreme expansion of their penultimate teeth into the ‘anvil’
313shape often associated with durophagy. This distinctive tooth morphology is also seen in many
314basal members of Globidonta, again interpreted to represent a durophagous feeding strategy (Fig.
3157). Although modern, generalist crocodylians sometimes exhibit durophagous behavior (Milàn et
316al. 2010), none has the expanded dentition of a true durophagy specialist. As such, beyond the
317predicted increase in secondary (i.e., crushing) damage to prey items, modern crocodylians
318possibly do not provide the best analogues for predicting the morphology of bite marks made by
319members of this clade.
321 Crocodylian and non-crocodylian crocodyliform bite marks long have been reported in
322the fossil record, and some recent publications discussed the presence or absence of the bisected
323marks. The patterns of bite marks reported here provide methods to predict expected traces in the
324fossil record. The results of the statistical analyses indicate that none of the recorded vital
325statistics or collection protocols correlate significantly with the expression of subscores (Table
3262). These results were somewhat surprising. Both ontogeny (e.g., McIlhenny, 1935; Erickson et
327al., 2014) and snout shape (e.g., Brochu, 2001; McHenry et al., 2006; Pierce et al., 2008; 2009)
328have been correlated with different tooth shapes and feeding ecologies, and yet analyses
329examining the relationships of associated features (i.e., age, lengths, body mass, ecomorph) to
330bisection presence or absence did not show any significant relationships. Captivity is known to
331trigger ecophenotypic change in crocodylians, particularly within the snout and tooth row (e.g.,
332Erickson et al., 2003; Sadleir, 2009; Drumheller et al., 2016), but again, whether these animals
333were wild caught or captive bred did not result in a significant difference between groups. Sexual Drumheller and Brochu | 16
334dimorphism is known in the clade (e.g., Hall and Portier, 1994; Verdade, 2003; Platt et al., 2009;
335Barrios-Quieroz et al., 2012), though the differences are often subtle and are more related to size
336rather than features of the feeding apparatus, so the lack of significant correlation here is
337unsurprising. Collection protocol (i.e., pig vs. cow bones, restrained vs. unrestrained during
338feeding) certainly provided complicating variables that could have affected bite mark expression,
339but these too failed to adequately explain the observed bite mark patterns. This leaves us with
340phylogenetic analyses of evolutionary relationships as a potential tool for synthesizing bite mark
341data and generating predictions regarding trace expression in the paleontological record. Here we
342present fossil case studies in order to test phylogenetic predictions reported in the Results
344 Crocodylus anthropophagus
345 The initial study of crocodylian bite marks by Njau and Blumenschine was specifically
346performed in order to address unusual patterns of traces present on fossils collected from the
347famous hominin site, Olduvai Gorge (2006). The possibility that crocodylians had been active
348taphonomic agents in the Olduvai environment, even predating on hominins, had been discussed
349previously (Davidson and Solomon 1990), but large-scale actualistic studies had not been
350performed to verify this interpretation. The survey of Crocodylus niloticus feeding traces by
351Njau and Blumenschine (2006), including the new bisected marks and hook scores, was fully
352consistent with the fossil marks present at Olduvai.
353 Recent analysis of Olduvai crocodylian material led to its classification as a new species
354of large, horned crocodylian, Crocodylus anthropophagus (Brochu et al. 2010). Crocodylian bite
355marks identified from the site were consistent with the size and inferred ecology of the new
356species, and with no other taxa seemingly present, a correlation between marks and specific Drumheller and Brochu | 17
357taxon was made.
358 As seen in Figure 5, C. anthropophagus is unambiguously (and accurately) predicted to
359have been capable of producing bisected marks.
360 Deinosuchus riograndensis
361 Schwimmer (2002, 2010) attributed bite marks on dinosaurian bones to Deinosuchus
362riograndensis based largely on the ovoid cross-sectional shape and the large size of the traces.
363No mention of bisected marks or other traces of a prominent carina was made. Even after the
364publication of potentially diagnostic crocodylian bite marks, including bisections (Njau and
365Blumenschine 2006), the record of Deinosuchus feeding traces has not been entirely clear
366(Brochu 2003). Large bisected marks were identified on hadrosaurid bones from the Upper
367Cretaceous of Coahuila, Mexico, which led researchers to point to D. riograndenesis as the
368potential trace maker (Rivera-Sylva et al. 2009). However, similar puncture marks on a turtle
369shell were also ascribed to this species, with no mention of bisected structures (Lehman and
370Wick 2010). Observation of both the published images and the specimen itself reveals a genuine
371absence of bisected marks on this specimen.
372 Even in the large surveys of modern taxa, bisected marks are not found on every single
373bone. In C. niloticus, the rate of bisections is ~10% of all marks occurring on 82.5% of all
374marked bones (Njau and Blumenschine 2006). Similar rates have been identified in Alligator
375mississippiensis (Drumheller and Brochu 2014). The spottiness of obvious bisections in the
376Deinosuchus bite mark literature therefore likely represents the relative paucity of current
377studies. Alternatively, Deinosuchus may have generated a smaller percentage of bisected marks,
378which, if the case, could help differentiate the species from other taxa based on a feature other
379than mark size. The potential for different rates of bisections to occur in modern crocodylian bite Drumheller and Brochu | 18
380marks has been tentatively explored using samples taken from Crocodylus porosus (Westaway et
381al. 2011) and Crocodylus niloticus (Baquedano et al. 2012). The only way to determine which (if
382either) of these proposed explanations is supported is with the identification of more marks
383associated with D. riograndensis.
384 Phylogenetic predictions made here only address presence or absence of bisected marks,
385not frequency of occurrence. Since one study does identify bisected marks associated with this
386taxon (Rivera-Sylva et al. 2009), bisections are determined to be ‘present’ in the clade, and were
387accurately predicted via the phylogenetic analysis (Fig. 5).
389 This study is limited to making predictions regarding presence or absence of subscores
390within the crown group. The patterns presented above are not trans-phylogenetic (sensu
391Rothschild 2015), and should only be applied to those groups bracketed by the sampled taxa.
392However, the inclusion of non-crocodylian crocodyliforms associated with bisected marks
393provides a method for expanding these predictions beyond the bounds of the crown group. For
394example, feeding traces, including bisected marks, have been reported on unionoid bivalves
395collected from the Lower Cretaceous Cameros Basin of Spain (Bermúdez-Rochas et al. 2013).
396Characteristics of the marks were compared to known crocodylomorphs from units of
397comparable age in the Iberian Peninsula, and an association with Goniopholis was made based
398on tooth size, spacing, and shape.
399 In another case study, a fossil rich locality in Texas representing a Cretaceous delta
400system has yielded a several species of crocodyliform and a number of bite marked turtle shells
401and dinosaurian bones (Adams et al. 2015). The marks exhibit bisections similar to those
402identified in modern crocodylians (Noto et al. 2012). The largest of these marks match the size, Drumheller and Brochu | 19
403shape, and arrangement of teeth in the jaw of a new species of crocodyliform discovered at the
405 Bisected pits also have been identified on turtle and crocodyliform remains from the Late
406Cretaceous Iharkút locality in western Hungary (Botfalvai et al., 2014). Several potential actors
407were discussed in that study, including a mosasaur and several species of crocodyliform. Dental
408morphology and body size were used to exclude all of those species but one, a currently
409undescribed, “Allodaposuchus-like” specimen present at the locality, whose size and dentition
410match the morphology of the feeding traces (Botfalvai et al., 2014; 2015).
411 If future uses of phylogenetic bracketing techniques can utilize these crocodyliforms as
412datapoints, phylogenetic predictions will be able to be projected beyond just the crown group. As
413it is, these examples of bisected marks found associated with multiple different crocodyliforms
414tentatively suggest that the condition might be plesiomorphic and therefore present across a
415broad spectrum of crocodylians and their more distant relatives.
416 Ziphodont Crocodyliforms
417 Of taxa included in this analysis, only three exhibit truly ziphodont teeth: the crocodylid
418Quinkana spp. and planocraniids Boverisuchus vorax and Boverisuchus geiseltalensis. The
419planocraniids Planocrania hengdongensis and Planocrania datagensis both have laterally
420compressed, recurved teeth, but without serrations. No modern crocodylian taxa exhibit
421ziphodonty, but other modern taxa have a convergent morphological condition that can be used
422to explore how this type of dentition is reflected in the bite mark record (D’Amore and
424 Based on work with Varanus komodoensis, ziphodont teeth leave striations that are
425associated with their serrations. These marks have been shown to correlate with metrics of body Drumheller and Brochu | 20
426size in different groups (D’Amore and Blumenschine 2012). Similar marks have been identified
427in the fossil record, and striation spacing, when compared to denticle morphology, has led to
428species-level associations between bite marks and actors in both theropod dinosaurs (D’Amore
429and Blumenschine 2009) and crocodyliforms (Alexander and Burger 2001). In the latter case,
430marked perissodactyl bones were identified within the gut contents of a Middle Eocene specimen
431of Boverisuchus vorax (previously classified as Pristichampsus vorax, see Brochu 2013).
432Striations on these bones were also consistent in size and spacing to denticles found in B. vorax
434 Ziphodonty is present in more basal crocodyliform groups as well, and associated bite
435marks exhibit similar patterns of morphology. Striated marks found on Baurusuchus
436salgadoensis and Baurusuchus pachecoi, two sebecosuchians from the Cretaceous of Brazil,
437have been cited as evidence of intraspecific fighting within Baurusuchidae (Avilla et al. 2004;
438deVasconcellos and Carvalho 2010), and gut contents from another baurusuchid, Aplestosuchus
439sordidus, demonstrate an unambiguous trophic interaction between this species and a
440sphagesaurid crocodyliform (Godoy et al., 2014). Beyond the baudusuchids, striation size and
441spacing have also been used to associate bite marks found on plesiosaur bones from the Jurassic
442of England with the marine crocodyliform Metriorhynchus (Forrest 2003).
443 Modern crocodylian bite marks are an inappropriate proxy for marks made by ziphodont
444crocodyliforms. Therefore, reported phylogenetic predictions based solely on modern taxa are
445equally inapplicable. However, since the connection between ziphodont teeth and striated bite
446marks has been established using both actualistic and paleontologic data (D’Amore and
447Blumenschine 2009; 2012), characters expressing these conditions may be tapped instead.
448Phylogenetic predictions of presence or absence of striated bite marks, based on characters Drumheller and Brochu | 21
449related to ziphodonty, are therefore reported in Figure 7.
450 Durophagous Crocodyliforms
451 Modern crocodylians that are dietary generalists sometimes exhibit feeding choices and
452behaviors associated with durophagy. Reports of crocodyliforms regularly feeding on turtles,
453crabs, and mollusks are quite common in both extant (e.g., Valentine et al. 1972; Thorbjarnarson
4541993; Grigg and Kirshner 2015) and extinct taxa (Carpenter and Lindsey 1980; Erickson 1984;
455Fuentes 2003; Karl and Tichy 2004; Mead et al. 2006; Steadman et al. 2007; Noto et al. 2012;
456Bermúdez-Rochas et al. 2013). However, no modern species retain the dental adaptations
457associated with requisite durophagy. Additionally, the only study dealing with actualistic traces
458of durophagous behavior in modern Paleosuchus palpebrosus focused on patterns of turtle shell
459breakage rather than individual bite marks (Milàn et al. 2010), patterns which have been echoed
460in the fossil record (Fuentes 2003; Noto et al. 2012), but are not easily included in the current
462 Of the taxa included in the phylogenetic analysis, some hylaeochampsids and basal
463members of Globidonta exhibit the expanded, anvil-like posterior teeth of truly durophagous
464crocodyliforms. With no extant crocodylians that exhibit this morphology to sample, and no
465actualistic research on more distantly related, durophagous taxa, it is difficult to predict how this
466feeding ecology might be expressed in the fossil record. However, from a strictly structural and
467functional point of view, it seems highly likely that bite marks generated would differ from the
468patterns made by less specialized groups. As such, these taxa are also considered to be potential
469exceptions to the phylogenetic predictions made in this analysis (Fig. 7).
470 Other Studies
471 Not all fossil bite marks can be directly associated with a particular species. When Drumheller and Brochu | 22
472crocodyliform diversity in a site is high (e.g., Irmis et al. 2011; Gianechini and de Valais 2015),
473the identification of potentially diagnostic marks and even embedded teeth cannot always
474definitively pinpoint a specific actor (e.g., Boyd et al. 2013). When species-level associations can
475be made, many methods of bite mark identification cannot be scored easily for analysis in a
476phylogenetic context. Mark size and spacing are both potentially useful features for identifying
477potential actors. Mark location on prey bone and geographic association of presumed predator
478and prey are more problematic methods of identifying trace makers, but are nevertheless often
479used. However, detailed physical descriptions of the marks themselves are required to identify
480the diagnostic traits that can be treated as codable characters. There is an extensive body of work
481describing crocodyliform bite marks on a variety of prey animals or conspecific competitors, but
482many of these published associations do not lend themselves well to phylogenetic scoring.
483Published studies specifically excluded from the analyses presented herein have been collected in
484Table 3, along with brief descriptions of the documented interactions and the method of
485identification and association. These studies were excluded based on a lack of species-level
486identification of the trace maker and/or detailed descriptions of mark morphology (i.e.,
487identifications of the associated crocodyliforms were based on the previously mentioned
489 Multiple Subscores
490 This study predicts taxa that should or should not produce bite marks with multiple
491subscores within a phylogenetic context (Fig. 6). At the present time, there are no published
492fossil studies with which to test these predictions. Multiple subscores, in the form of trisections
493and quadrisections, were only visible under high magnification with the use of a VP-SEM. In the
494existing literature, bite marks are rarely subjected to this level of scrutiny. Future studies Drumheller and Brochu | 23
495attempting to differentiate bite marks at fine taxonomic scales should consider higher
496magnification investigation as a potential source of useful data.
497 In the meantime, large-scale patterns associated with multiple subscores in crocodylian
498bite marks remain uncertain; marks may reflect a complexity to crocodylian tooth structure and
499carina shape which has not been described previously. Alternatively, they may represent
500pathological anomalies that do not carry a phylogenetic signal. Other archosaurs are known to
501have teeth with pathological split carinae (Erickson 1995), and undescribed crocodylid material
502from the Pliocene of Ethiopia has similar pathologies (J. Thompson, pers. obs.). This aspect of
503crocodylian bite mark morphology requires further study.
504 However, if these multiple subscores represent pathological alterations to the carina of
505crocodylians, it does imply that non-pathological, freshly erupted teeth should be able to
506generate standard bisected marks. If this is assumed to be the case, and if the character state
507codings for Osteolaemus tetraspis (the only species observed to make multiple subscores, but not
508bisections), the only area of ambiguity in the tree exploring the distribution of bisections resolves
509to the bisected character state, making our predictions of this feature an unambiguously clade-
510wide phenomenon (Fig. 5).
512 Observing the anatomy, behavior, and ensuing bite marks created by a single taxon and
513then projecting those observations onto a large and historically diverse clade can be problematic.
514Among related, extant animals with similar tooth morphologies, it has been shown that
515differences in dietary niche and feeding strategy can be reflected in bite mark morphology
516(Klippel and Synstelien 2007). Ideally, samples should be taken from multiple different taxa in
517order to help determine what patterns are, and are not, actually shared across groups. However, Drumheller and Brochu | 24
518the best way to synthesize multiple sources of such data, beyond qualitatively comparing and
519contrasting patterns, has not been the subject of significant study.
520 In this instance, patterns of subscore presence or absence in crocodylians did not
521statistically correlate with any recorded variable related to collection protocol, animal size, age,
522sex, or origin. Placing the feeding traces into a phylogenetic context did indicate that bisected
523marks should be present across almost all of crown Crocodylia, and did successfully predict the
524presence of these marks in a sampling of published fossil case studies (Njau and Blumenschine
5252006; Brochu et al. 2010; Rivera-Sylva et al. 2009). Bisected marks are also predicted to occur
526among more basal groups as well, due to fossil discoveries linking bisected marks to several
527different crocodyliforms (Noto et al. 2012; Bermúdez-Rochas et al. 2013; Botfalvai et al. 2014;
5282015). Patterns pertaining to multiple subscores were less definitive, and the need for further
530 Exploring patterns of bite marks using the extant phylogenetic bracket (Witmer 1995)
531does have limitations – diagnostic bite mark types are not always present on every modified bone
532in an assemblage, and as actualistic data can only be collected from extant forms, it cannot
533sample now-extinct behaviors and morphologies. However, even in the absence of modern data
534collected in a phylogenetic framework, phylogenies can still direct when and where more
535distantly related proxies would be most appropriate to apply. Among crocodyliforms, this is best
536exemplified by now-extinct clades that exhibited dental adaptations related to ziphodonty and
538 Comparisons between actualistic taphonomic datasets are often qualitative rather than
539quantitative, due to the highly variable nature of sample collection protocols. This has limited
540our ability to tease out large-scale patterns using statistical tests and phylogenetic techniques. Drumheller and Brochu | 25
541Instituting a truly universal method for collecting, for example, bite mark datasets may not be
542viable, considering the variety of research taxa and questions these studies might address.
543However, the use of more detailed reporting methods does open certain avenues of analysis that
544have been previously underutilized, including parsimony- (Witmer 1995) and model-based
545techniques (Pagel 1999; Pagel et al. 2004). In this case study, surveying the bite marks across
546most of the extant species within Crocodylia, indicates that statistical tests and applications of
547extant phylogenetic bracketing has great potential for making taphonomic predictions.
549 The Saint Augustine Alligator Farm, director J. Brueggen, and curator of reptiles D.
550Kledzik provided access to and aid working with animals. Southeastern Provisional and
551Swaggerty’s Farms provided the cow and pig samples. J. Horton, F. and J. Drumheller, and H.
552Berg helped with specimen collection and processing. Support was provided though NSF DEB
5530444133 and DEB 1257786-125748 to C. Brochu and the University of Iowa Department of
554Earth and Environmental Sciences Littlefield Family Fund to S. Drumheller. The Iowa
555Department of the State Archaeologist and the Frank H. McClung Museum of Natural History of
556Culture provided storage space and equipment for sample processing and imaging. The
557University of Iowa Central Microscopy Research Laboratories provided training and access to
558scanning electron microscopes. This study represents part of a dissertation completed in partial
559fulfillment of a PhD at the University of Iowa. Committee members included: N. Budd, J. Enloe,
560J. Adrain, H. Sims, and W. Klippel. The following people also provided helpful discussion,
561feedback, and encouragement: M. Stocker, E. Wilberg, M. Spencer, two anonymous reviewers,
562and the UI Paleontological Discussion Group.
563 LITERATURE CITED Drumheller and Brochu | 26
564ADAMS, T.L., NOTO, C.R., and DRUMHELLER, S.K., 2015, The crocodyliform diversity of the
565 Woodbine Formation (Cenomanian) of Texas and the transition from Early to mid-
566 Cretaceous ecosystems. Society of Vertebrate Paleontology Annual Meeting: Journal of
567 Vertebrate Paleontology, v. Program and Abstracts, p. 77.
568ALEXANDER, J.P. and BURGER B.J., 2001, Stratigraphy and taphonomy of Grizzly Buttes,
570 Biodiversity: Unusual Occurences and Rarely Sampled Habitats: Kluwer
571 Academic/Plenum Publishers, New York, p., 165–196.
572ALLEN, E., MAIN, D., and NOTO, C., 2011 A new crocodyliform from the Middle Cretaceous
573 Woodbine Formation of Texas. Journal of Vertebrate Paleontology: Suppl. to v. 3, p. 61.
574AVILLA, L.S., FERNANDES, R., and RAMOS, D.F.B., 2004, Bite marks on a crocodylomorph from
575 the Upper Cretaceous of Brazil: evidence of social behavior? Journal of Vertebrate
576 Paleontology: v. 24(4), p. 971–973.
577BARRIOS-QUIEROZ, G., CASAS-ANDREU, G., AND ESCOBEDO-GALVÁN, A.H., 2012. Sexual size
578 dimorphism and allometric grown of Morelet’s crocodiles in captivity. Zoological
579 Science: v. 29, p. 198–203
580BAQUEDANO, E. DOMÍNGUEZ-RODRIGO, M., and MUSIBA, C., 2012, An experimental study of
581 large mammal bone modification by crocodiles and its bearing on the interpretation of
583 p. 1728–1737.
584BERMÚDEZ-ROCHAS, D.D., DELVENE, G., and RUIZ-OMEÑACA, J.I., 2013, Evidence of predation
585 in Early Cretaceous unionoid bivalves from freshwater sediments in the Cameros Basin,
586 Spain. Lethaia: v. 46(1), p. 57–70. Drumheller and Brochu | 27
587BINFORD, L.R., 1981, Bones: Ancient Men and Modern Myths. Academic Press, New York.
588BLOMBERG, S.P., GARLAND Jr., T., and IVES, A.R., 2003, Testing for phylogenetic signal in
589 comparative data: behavioral traits are more labile. Evolution: v. 57(4), p. 717–745.
590BLUMENSCHINE, R.J., MAREAN, C.W., and CAPALDO, S.D., 1996, Blind test of inter-analyst
591 correspondence and accuracy in the identification of cut marks, percussion marks, and
592 carnivore tooth marks on bone surfaces. Journal of Archaeological Science: v. 23(4), p.
594BOTFALVAI, G., PRONDVAI, E., and ŐSI, A., 2014, Inferred bite marks on a Late Cretaceous
595 (Santonian) bothremydid turtle and a hylaeochampsid crocodilian from Hungary.
596 Cretaceous Research: v. 50, p. 304–317.
597BOTFALVAI, G., ŐSI, A., and MINDSZENTY, A., 2015. Taphonomic and paleoecologic
598 investigations of the Late Cretaceous (Santonian) Iharkút vertebrate assemblage (Bakony
599 Mts, Northwestern Hungary). Palaeogeography, Palaeoclimatology, Palaeoecology: v.
600 417, p. 379–405.
601BOYD, C.A., DRUMHELLER, S.K., and GATES, T.A., 2013, Crocodyliform Feeding Traces on
602 Juvenile Ornithischian Dinosaurs from the Upper Cretaceous (Campanian) Kaiparowits
603 Formation, Utah. PLoS ONE: v. 8(2), p. e57605, doi: 10.1371/journal.pone.0057605.
604BRAIN, C.K., 1981, The Hunters of the Hunted? An Introduction to African Cave Taphonomy.
605 The University of Chicago Press, Chicago.
606BRAZAITIS, P. and WATANABE, M.E., 2011, Crocodilian behavior: a window to dinosaur
607 behavior? Historical Biology: v. 23(1), p. 73–90.
608BROCHU, C.A., 2001. Crocodylian snouts in space and time: phylogenetic approaches toward
609 adaptive radiation. American Zoologist: v. 41(3), p. 564–585. Drumheller and Brochu | 28
610BROCHU, C.A., 2003, King of the Crocodylians: The Paleobiology of Deinosuchus. Palaios: v.
611 18(1), p. 80–82.
612BROCHU, C.A., 2013, Phylogenetic relationships of Palaeogene ziphodont eusuchians and the
613 status of Pristichampsus Gervais, 1853. Earth and Environmental Science Transactions of
614 the Royal Society of Edinburgh: v. 103(3–4), p. 521–550.
615BROCHU, C.A., NJAU, J., BLUMENSCHINE, R.J., and DENSMORE, L.D., 2010, A new horned
616 crocodile from the Plio-Pleistocene hominid sites at Olduvai Gorge, Tanzania. PLoS
617 One: v. 5(2), p. e9333, doi: 10.1371/journal.pone.0009333.
618BROCHU, C.A., PARRIS, D.C., GRANDSTAFF, B.S., DENTON Jr., R.K., and GALLAGHER, W.B.,
619 2012, A new species of Borealosuchus (Crocodyliformes, Eusuchia) from the Late
621 p. 105–116.
622BROCHU, C.A. and STORRS, G.W., 2012, A giant crocodile from the Plio-Pleistocene of Kenya,
623 the phylogenetic relationships of Neogene African crocodylines, and the antiquity of
624 Crocodylus in Africa. Journal of Vertebrate Paleontology: v. 32(3), p. 587–602.
625BUFFETAUT, E., 1983, Wounds on the jaw of an Eocene mesusuchian crocodilian as possible
626 evidence for the antiquity of crocodilian intraspecific fighting behavior. Paleontologische
627 Zeitschrift: v. 57, p. 143–145.
628BYERS, S.N., 2005, Introduction to forensic anthropology: a textbook. Pearson/Allyn and Bacon,
629 New York.
631 (Alligatorinae; Crocodylidae), a Late Cretaceous turtle-eating alligator. Journal of
632 Paleontology: v. 54, p. 1213–1217. Drumheller and Brochu | 29
633CASAL, G.A., MARTÍNEZ, R.D., IBIRICU, L.M., RIGA, B.G., and FOIX, N., 2013, Tafonomía del
634 dinosaurio terópodo Anikosaurus darwini, Formación Bajo Barreal, Cretácico Tardío de
635 Patagonia (Argentina). Ameghiniana: v. 50(6), p. 571–592.
636CHATTOPADHYAY, S., SHEE, B., and SUKUL, B. 2013, Fatal crocodile attack. Journal of Forensic
637 and Legal Medicine: v. 20, p. 1139–1141.
638CISNEROS, J.C., 2005, New Pleistocene vertebrate fauna from El Salvatore. Revista Brasileira de
639 Paleontologia: v. 8(3), p. 239–255.
640CRUZ-URIBE, K., 1991, Distinguishing hyena from hominid bone accumulations. Journal of Field
641 Archaeology: v. 18(4), p. 467–486.
642CUPAL-MAGAÑA, F.F., RUBIO-DELGADO, A., REYES-NÚÑEZ, C., TORRES-CAMPOS, E., and
643 SOLÍS-PECARO, L.A., 2010, Ataques de cocodrilo de río (Crocodylus acutus) en Puerto
644 Vallarta, Jalisco México: presentación de cinco casos American crocodile (Crocodylus
645 acutus) attacks in Puerto Vallarta, Jalisco, Mexico: Presentation of five cases. Cuad Med
646 Forense: v. 16(3), p. 153–160.
647D’AMORE, D.C. and BLUMENSCHINE, R.J., 2009, Komodo monitor (Varanus komodoensis)
648 feeding behavior and dental function reflected through tooth marks on bone surfaces, and
649 the application to ziphodont paleobiology. Paleobiology: v. 35(4), p. 525–552.
650D’AMORE, D.C. and BLUMENSCHINE, R.J., 2012. Using striated tooth marks on bone to predict
651 body size in theropod dinosaurs: a model based on feeding observations of Varanus
652 komodoensis, the Komodo monitor. Paleobiology 38(1):79–100.
653DAVIDSON, I. and SOLOMAN, S., 1990, Was OH7 the victim of a crocodile attack? in Solomon, Drumheller and Brochu | 30
654 S., Davidson, I., and Watson, D. (eds.) Problem Solving in Taphonomy: Archaeological
655 and Palaeontological Studies from Europe, Africa and Oceania: Tempus, St. Lucia,
656 Queensland, p. 197–206.
657DE PINNA, M.G.G., 1991, Concepts and tests of homology in the cladistic paradigm. Cladistics:
658 v. 7, p. 367–394.
659DE QUIEROZ, A. and WINBERGER, P.H., 1993, The usefulness of behavior for phylogeny
660 estimation: levels of homoplasy in behavioral and morphological characters. Evolution:
661 v. 47(1), p. 46–60.
662DE VASCONCELLOS, F.M. and CARVALHO, I. DeS., 2010, Paleoichnological assemblage
663 associated with Baurusuchus salgadoensis remains, a Baurusuchidae Mesoeucrocodylia
664 from the Bauru Basin, Brazil (Late Cretaceous). in Lucas, S.G., Lockley, M.G., and
665 Spielmann, J.A. (eds.) Crocodyle Tracks and Traces. New Mexico Museum of Natural
666 History and Science, Bulletin 51, p. 227–238.
667DOMÍNGUEZ-RODRIGO, M. 1999, Flesh availability and bone modifications in carcasses
668 consumed by lions: paleoecological relevance in hominid foraging patterns.
669 Palaeogeography, Palaeoclimatology, and Palaeoecology: v. 149, p. 373–388.
670DOMÍNGUEZ-RODRIGO, M. and PIQUERAS, A., 2003, The use of tooth pits to identify carnivore
671 taxa in tooth-marked archaeofaunas and their relevance to reconstruct hominid carcass
672 processing behaviors. Journal of Archaeological Sciences: v. 30, p. 1385–1391.
673DRUMHELLER, S.K., 2007, Experimental taphonomy and microanalysis of crocodylian feeding
674 traces. Microscopy and Microanalysis: v. 13, p. 510CD.
675DRUMHELLER, S.K. and BROCHU, C.A., 2014, A diagnosis of Alligator mississippiensis bite
676 marks with comparisons to existing crocodylian datasets. Ichnos: v. 21, p. 131–146. Drumheller and Brochu | 31
677DRUMHELLER, S.K., STOCKER M.R., AND NESBITT, S.J., 2014. Direct evidence of trophic
678 interactions among apex predators in the Late Triassic of western North America.
679 Naturwissenschaften, v. 101, p. 975–987.
680DRUMHELLER, S.K., WILBERG, E.W., AND SADLEIR, R.W., 2016. The utility of captive animals
682 actualistic research: a geometric morphometric exploration of the tooth row of Alligator
683 mississippiensis suggesting ecophenotypic influences and functional constraints. Journal
684 of Morphology: doi: 10.1002/jmor.20540.
685ERICKSON, B.R., 1984, Chelonivorous habits of the Paleocene crocodile Leidysuchus
686 formidabilis. Scientific Publications of the Science Museum of Minnesota, New Series: v.
687 5, p. 1–9.
688ERICKSON, G.M., 1995, Split carinae on tyrannosaurid teeth and implications of their
689 development. Journal of Vertebrate Paleontology: v. 15(2), p. 268–274.
690ERICKSON G.M., LAPPIN A.K., PARKER, T., AND VLIET, K.A., 2003. Comparison of bite-force
691 performance between long-term captive and wild American alligators (Alligator
692 mississippiensis). Journal of Zoology: v. 262, p. 21–28.
693ERICKSON, G.M., GIGNAC, P.M., STEPPAN, S.J., LAPPIN, A.K. VLIET, K.A., BREUGGEN, J.D.,
694 INOUYE, B.D., KLEDZIK, D., AND WEBB, G.J.W., 2014. A comparative analysis of
695 ontogenetic bite-force scaling among Crocodylia. Journal of Zoology: v. 292, p. 48–55.
696EVGEN Z., MYKOLA, U., and ANDRIY, B., 2012, The locality of Eocene vertebrates Ikovo
697 (Luhansk Region, Ukraine): Ecologo-taphonomic analysis. Paleontological Review: v.
698 44, p. 107–122.
699FENTON, T.W., BIRKBY, W.H., and CORNELISON, J., 2003, A fast and safe non-bleaching method Drumheller and Brochu | 32
700 for forensic skeletal preparation. Journal of Forensic Sciences: v. 48(1), p. 274–276.
701FISHER, R.A., 1925. Statistical Methods for Research Workers. Genesis Publishing Pvt Ltd, New
703FORREST, R., 2003, Evidence for scavenging by the marine crocodile Metriorhynchus on the
704 carcass of a plesiosaur. Proceedings of the Geologists’ Association: v. 144, p. 363–366.
705FUENTES, E.J., 2003, Predación crocodiliana a quelonios. Un Neochelys (Pelomedusidae), del
706 Eoceno de Zemora, lisiando por un Asiatosuchus. Studia Geologica Salmanticensia: v.
707 39, p. 11–23.
708GIANECHINI, F.A. and DE VALAIS, S., 2015, Bioerosion trace fossils on bones of the Cretaceous
709 South American theropod Buiteraptor gonzalezorum Makovicky, Apesteguía and
710 Agnolín, 2005 (Deinonychosauris). Historical Biology:
712GODOY, P.L., MONTEFELTRO, F.C., NORRELL, M.A., and Langer, M.C., 2014, An additional
713 Baurusuchis from the Cretaceous of Brazil with evidence of interspecific predation
714 among Crocodyliformes. PLoS One: v. 9(5), p. e97138,
716GOLOBOFF, P.A., FARRIS, J.A., and NIXON, K.C., 2008, TNT, a free program for phylogenetic
717 analysis. Cladistics: v. 24, p. 1–13.
718HAGLUND, W.D., 1997a, Dogs and Coyotes: Postmortem Involvement with Human Remains, in
719 Haglund, W.D. and Sorg, M.H. (eds.), Forensic Taphonomy: The Postmortem Fate of
720 Human Remains: CRC Press, Boca Raton, p. 376–381.
721HAGLUND, W.D., 1997b, Rodents and Human Remains. in Haglund, W.D. and Sorg, M.H.
722(eds.), Drumheller and Brochu | 33
723 Forensic Taphonomy: The Postmortem Fate of Human Remains: CRC Press, Boca
724 Raton, p. 405–414.
725HALL, P.M., AND PORTIER, K.M., 1994. Cranial morphometry of New Guinea crocodiles
726 (Crocodylus novaeguineae): Ontogenetic variation in relative growth of the skull and an
727 assessment of its utility as a predictor of the sex and size of individuals. Herpetological
728 Monographs: v. 8, p. 203–225.
729HAMMER, Ø., HARPER, D.A.T., and RYAN, P.D., 2001, PAST: Paleontological statistics software
730 package for education and data analysis. Paleontologica Electronica: v. 4(1),
732HARDING, B.E. and WOLF, B.C., 2006, Alligator attacks in southwest Florida. Journal of
733 Forensic Sciences: v. 51(3), p. 674–677.
734HASTINGS, A.K., BLOCH, J.I., and JARAMILLO, C.A., 2015, A new blunt-snouted dyrosaurud,
735 Anthracosuchus balrogus gen. et sp. Nov. (Crocodylomorpha, Mesoeucrocodylia), from
736 the Palaeocene of Colombia. Historical Biology: v. 27(8), p. 998–1020.
737HAYNES, G., 1982, Utilization and skeletal disturbances of North American prey carcasses.
738 Arctic: v. 35(2), p. 266–281.
739HAYNES, G., 1983, A guide for differentiating mammalian carnivore taxa responsible for gnaw
740 damage to herbivore long bones. Paleobiology: v. 9(2), p. 164–172.
741IRMIS, R., SERTICH, J., HUTCHISON, J., and TITUS, A., 2011, Campanian crocodyliforms of
742 Laramidia: new insights from the Kaiparowits Basin of southern Utah. Journal of
743 Vertebrate Paleontology: Suppl. To v. 3, p. 130.
744KARL, H.-V. and TICHY, G., 2004, The structure of fossil teeth of chelonophagous crocodiles
745 (Diapsida: Crocodylia). Studia Geologica Salmanticensia: v. 40, p. 115–124. Drumheller and Brochu | 34
746KATSURA, Y., 2004, Paleopathology of Toyotamaphimeis machikanensis (Diapsida,
747 Crocodylia) from the Middle Pleistocene of central Japan. Historical Biology: v. 16(2), p.
749KLIPPEL, W.E. and SYNSTELIEN, J.A., 2007, Rodents as taphonomic agents: Bone gnawing by
750 brown rats and gray squirrels. Journal of Forensic Sciences: v. 52, p. 765–773.
751KRUSKAL, W.H. and WALLIS, W.A., 1952, Use of ranks in one-criterion variance analysis.
752 Journal of the American Statistical Association: v. 47. P. 583–621.
753LEHMAN, T.M. and WICK, S.L., 2010, Chupacabrachelys complexus, n. gen. n. sp. (Testudines:
755 Vertebrate Paleontology: v. 30(6), p. 1709–1725.
756LEVENE, H., 1960, Robust tests for equality of variances. in Olkin, I., Ghurye, S.G., Hoeffding,
757 W., Madow, W.G., and Mann, H.B. (eds.), Contributions to Probability and Statistics:
758 Essays in Honor of Harold Hotelling: Stanford University Press, p. 278–292.
759LYMAN, R.L., 1994, Vertebrate Taphonomy. Cambridge University Press, Cambridge.
760MACKNESS, B.S., COOPER, J.E., WILKINSON, C., and WILKINSON, D., 2010, Paleopathology of a
761 crocodile femur from the Pliocene of eastern Australia. Alcheringa: An Australasian
762 Journal of Paleontology: v. 34(4), p. 515–521.
763MADDISON, W.P. and MADDISON, D.R., 2011. Mesquite: a modular system for evolutionary
764 analysis. Version 2.75.
765MAIRS, S., SWIFT, B., and RUTTY, G.N., 2004, Detergent: An alternative approach to traditional
766 bone cleaning methods for forensic practice. American Journal of Forensic Medical
767 Pathology: v. 25, p. 276–284.
768MAREAN, C.W. and SPENCER, L.M., 1991, Impact of carnivore ravaging on zooarchaeological Drumheller and Brochu | 35
769 measures of element abundance. American Antiquity: v. 56(4), p. 645–658.
770MARTIN, J.E., 2013, Surviving a potentially lethal injury? Bite mark and associated trauma in the
771 vertebra of a dyrosaurid crocodilian. Palaios: v. 28, p. 6–8.
772MCHENRY C.R., CLAUSEN, P.D., DANIEL, W.J.T., MEERS, M.B., AND PENDHARKAR, A., 2006.
773 Biomechanics in the rostrum in crocodilians: a comparative analysis using finite-element
774 modeling. Anatomical Record Part A: v. 288A, p. 827–849.
775MCILHENNY, E.A., 1935. Alligator’s Life History. Ten Speed Press, Berkeley.
776MEAD, J., CUBERO, R., ZAMORA, A., SWIFT, S., LAURITO, C., and GÓMEZ, L. 2006, Plio-
777 Pleistocene Crocodylus (Crocodilia) from southwestern Costa Rica. Studies on
778 Neotropical Fauna and Environment: v. 41, p. 1–7.
779MENDIETA, C. and DUARTE, A., 2009, Ataque por anemales acuáticoes (tiburón y cocodrilo). A
780 propósito de dos casos fatales en la provincial de Bocas del Toro (Panamá). Attack for
781 aquatic animals (shark and alligator). Report of two fatal cases in the Bocas del Toro
782 province (Panama). Cuad Med Forense: v. 15(58), p. 309–315.
783MIKULÁS, R., KADLECOVÁ, E., FEJFAR, O., and DVOŘÁK, Z., 2006, Three new ichnogenera of
784 biting and gnawing traces on reptilian and mammalian bones: a case study from the
785 Miocene of the Czech Republic. Ichnos: v. 13, p. 113–127.
786MILÀN, J., KOFOED, J. and BROMLEY, R.G., 2010, Crocodylian-chelonian carnivory: bite traces
787 of dwarf caiman, Paleosuchus palpebrosus, in red-eared slider, Trachemys scripta,
788 carapaces. in Lucas, S.G., Lockley, M.G., and Spielmann, J.A. (eds.), Crocodyle Tracks
789 and Traces: New Mexico Museum of Natural History and Science, Bulletin 51, p. 195–
791MILÀN, J., LINDOW, B.E.K., and LAURIDSEN, B.W., 2011, Bite traces in a turtle carapace Drumheller and Brochu | 36
792 fragment from the middle Danian (Lower Paleocene) bryozoans limestone, Faxe,
793 Denmark. Bulletin of the Geological Society of Denmark: v. 59, p. 61–67.
794MORGAN, G.S. and ALBURY, N.A., 2013, The Cuban crocodile (Crocodylus rhombifer) from the
796 Natural History Bulletin: 52(3), p. 161–236.
797NARVÁEZ, I., BROCHU, C.A., ESCASO, F., PÉREZ-GARCÍA, A., and ORTEGA, F., 2015, New
798 Crocodyliforms from Southwestern Europe and Definition of a Diverse Clade of
799 European Late Cretaceous Basal Eusuchians. PLoS One: v. 10(11), p. e0140679,
801NJAU, J.K. and BLUMENSCHINE, R.J., 2006, A diagnosis of crocodile feeding traces on larger
802 mammal bone, with fossil examples from the Plio-Pleistocene Olduvai Basin, Tanzania.
803 Journal of Human Evolution: v. 50(2), p. 142–162.
804NOTO, C.R., MAIN, D.J., and DRUMHELLER, S.K., 2012, Feeding traces and paleobiology of a
805 Cretaceous (Cenomanian) crocodyliform: example from the Woodbine Formation of
806 Texas. Palaios: v. 27(2), p. 105–115.
807PAGEL, M., 1999, A maximum likelihood approach to reconstructing ancestral character states of
808 discrete characters on phylogenies. Systematic Biology: v. 48(3), p. 612–622.
809PAGEL, M., MEADE, A., and BARKER, D., 2004, Bayesian estimation of ancestral character states
810 on phylogenies. Systematic Biology: v. 53(5), p. 673–684.
811PEARSON, K. 1900. On the criterion that a given system of deviations from the probable in the
812 case of a correlated system of variables is such that it can be reasonably supposed to have
813 arisen from random sampling. Philosophical Magazine Series 5: v. 50(302), p. 157–175. Drumheller and Brochu | 37
814PIERCE, S.E., ANGIELCZYK, K.D., AND RAYFIELD, E.J., 2008. Patterns of morphospace
816 and mechanical performance in extant crocodilian skulls: a combined geometric
817 morphometric and finite element modeling approach. Journal of Morphology: v. 269, p.
819PIERCE, S.E., ANGIELCZYK, K.D., AND RAYFIELD, E.J., 2009. Shape and mechanics in
820 thalattosuchuan (Crocodylomorpha) skulls: implications for feeding behavior and niche
821 partitioning. Journal of Anatomy: c. 215, p. 555–576.
822PLATT, S.G., RAINWATER, T.R., THORBJARNARSON, J.B., FINGER, A.G., ANDERSON, T.A., AND
823 MCMURRY, S.T., 2009. Size estimation, morphometrics, sex ration, sexual size
824 dimorphism, and biomass of Morelet’s crocodile in northern Belize. Caribbean Journal of
825 Science: v. 45(1), p. 80–93.
826RIVERA-SYLVA, H.E., FREY, E., and GUZMÁN-GUTIÉRREZ, J.R., 2009, Evidence of predation on
827 the vertebra of a hadrosaurid dinosaur from the Upper Cretaceous (Campanian) of
828 Coahuila, Mexico. Carnets de Géologie/Notebooks on Geology Letter: 2.
829ROTHSCHILD, B.M., 2015, Unexpected behavior in the Cretaceous: tooth-marked bone attributed
830 to tyrannosaur play. Ethology Ecology & Evolution: v. 27(3), p. 325–334.
831SADLEIR, R.W., 2009. A morphometric study of crocodylian ecomorphology through ontogeny
832 and phylogeny. Unpublished Ph.D. dissertation. The University of Chicago Division of
833 the Biological Sciences and Pritzker School of Medicine, Chicago.
834SARTAIN, S.E. and STEELE, R.W., 2009, An alligator bite. Clinical Pediatrics: v. 48, p. 564.
835SCHWIMMER, D.R., 2002, King of the crocodylians: The paleobiology of Deinosuchus, Indiana
836 University Press, Bloomington. Drumheller and Brochu | 38
837SCHWIMMER, D.R., 2010, Bite barks of the giant crocodylian Deinosuchus on Late Cretaceous
838 (Campanian) bones, in Lucas, S.G., Lockley, M.G., and Spielmann, J.A. (eds.),
839 Crocodyle Tracks and Traces: New Mexico Museum of Natural History and Science,
840 Bulletin 51, p. 183–190.
841SHAPIRO, S.S. AND WILK, M.B., 1965, An analysis of variance test for normality (complete
842 samples). Biometrika, v. 52, p. 591–611.
843SHELTON, S.Y. and BUCKLEY, J.S., 1990, Observations on enzyme preparation effects on skeletal
844 material. Collection Forum: v. 6(2), p. 76–81.
845STEADMAN, D.W., DIANTONIO, L.L. WILSON, J.J., SHERIDAN, K.E., and TAMMARIELLO, S.P.,
846 2006. The effects of chemical and heat maceration techniques on the recovery of nuclear
847 and mitochondrial DNA from bone. Journal of Forensic Sciences: v. 51(1), p. 11–17.
848STEADMAN, D.W., FRANZ, R., MORGAN, G.S., ALBURY, N.A., KAKUK, B., BROAD, K., FRANZ,
849 S.E., TINKER, K., PATEMAN, M.P., LOTT, T.A., JARZEN, D.M., and DILCHER, D.L., 2007,
850 Exceptionally well preserved late Quaternary plant and vertebrate fossils from a blue hole
851 on Abaco, The Bahamas. Proceedings of the National Academy of Sciences: v. 104, p.
853THORBJARNARSON, J.B., 1993, Diet of the spectacled caiman (Caiman crocodiles) in the Central
854 Venezuelan Llanos. Herpetologica: v. 49(1), p. 108–117.
855TULLBERG, B.S., AH-KING, M., and TEMRIN, H., 2002, Phylogenetic reconstruction of parental-
856 care systems in the ancestor of birds. Philosophical Transactions of the Royal Society of
857 London: v. 357, p. 251–257.
858VALENTINE, J.M., WALTHER, J.R., MCCARTNEY, K.M., and IVY, L.M., 1972, Alligator diets on Drumheller and Brochu | 39
859 the Sabine National Wildlife Refuge, Louisiana. The Journal of Wildlife Management: v.
860 36(3), p. 809–815.
861VERDADE, L.M., 2003. Cranial sexual dimorphism in captive adult broad-snouted caiman
862 (Caiman latirostris). Amphibia Reptilia: v. 24(1), p. 92–99.
863WEBB, G.J.W. and MANOLIS, S.C., 1983, Crocodylus johnstoni in the McKinlay River Area N.
864 T, V.* abnormalities and injuries. Australian Wildlife Research: v. 10(2), p. 407–420.
865WESCOTT, D.J., 2013, Biomechanics of bone trauma, in Encyclopedia of forensic sciences:
866 Academic, New York, p. 83–88.
867WESTAWAY, M.C., THOMPSON, J.C., WOOD, W.B., and NJAU, J., 2011, Crocodile ecology and
868 the taphonomy of early Australasian sites. Environmental Archaeology: v. 16(2), p. 124–
870WILLIAMSON, W.E., 1996, ?Brachychampsa sealeyi, sp. nov., (Crocodylia, Alligatoroidea) from
871 the Upper Cretaceous (Lower Campanian) Menefee Formation, northwestern New
872 Mexico. Journal of Vertebrate Paleontology: v. 16(3), p. 421–431.
873WOOD, W.B., 2008, Forensic identification in fatal crocodile attacks. in Oxenham, M. (ed.)
874 Forensic Approaches to Death, Disaster and Abuse: Australian Academic Press,
875 Brisbane, QLD, Australia, p. 243–260.
877 FIGURE CAPTIONS
878FIG. 1 .—Examples of bite mark collection protocols. A) Unrestrained Caiman latirostris. B)
879restrained Alligator sinensis. Drumheller and Brochu | 40
881FIG. 2 —A) Line drawing of generalized bite mark types using Binford’s (1981) classification
882scheme. B) Two pits made by SAAF A03048 Crocodylus acutus. C) Punctures made by SAAF
883A03048 Crocodylus acutus. D) Score made by SAAF 86052 Alligator sinensis. E) Furrow made
884by SAAF A05004 Crocodylus novaeguineae. Scale bars = 1 cm. Drumheller and Brochu | 41
886FIG. 3 —Line drawing of pitted bone comparing bisected and unbisected marks with examples of Drumheller and Brochu | 42
887associated tooth morphologies. VP-SEM images of bisected and quadrisected marks with
888margins indicated with black arrows and subscores indicated with white arrows. A) Relatively
889unworn, highly carinated Crocodylus acutus tooth associated with bisected marks. B) Worn,
890chipped C. acutus tooth associated with unbisected marks (Fig. 2) and sometimes microstriations
891(Fig. 4A). C) Bisected score made by SAAF A04004 Crocodylus johnsoni. D) Bisected pit made
892by SAAF A05006 Crocodylus novaeguineae. E) Quadrisected score made by SAAF 88130
893Alligator sinensis. F) Quadrisected score made by SAAF A04004 C. johnsoni. A and B courtesy
894E. Wilberg. Scale bars = 5 mm. Drumheller and Brochu | 43
896FIG. 4 —Secondary alterations made by modern crocodylian trace makers. A) SAAF A01025 A.
897mississippiensis puncture with depressed fractures and fracture lines indicated with a black
898arrow. Microstriations within drag out scores indicated with a white arrow. B) SAAF ‘Fluffy’ A.
899mississippiensis puncture, indicated with a black arrow, and a depressed fracture, indicated with
900a white arrow. C) SAAF A01025 A. mississippiensis spiral fracture. D) SAAF A05004 C. Drumheller and Brochu | 44
901novaeguineae possible mark from a broken tooth with irregular scoring with microstriations
902indicated with a black arrow. Photograph scale bars (A, B, and C) = 1 cm. VP-SEM scale bar (D)
903= 1 mm.
905FIG. 5 —Phylogenetic tree showing character states for bisected bite mark characters across key
906clades within Eusuchia. Drumheller and Brochu | 45
908FIG. 6 —Phylogenetic tree showing character states for multiple subscore characters across key
909clades within Eusuchia. Drumheller and Brochu | 46
911FIG. 7 —Phylogenetic tree showing character states for dental characters across key clades
912within Eusuchia that are related to ziphodonty and durophagy. Drumheller and Brochu | 47
915TABLE 1 —Types of bite marks and modifications caused by crocodylians, organized by species.
916X = Present in this survey. 1 = Present in Njau and Blumenschine, 2006. 2 = Present in Drumheller and Brochu | 48
917Westaway et al., 2011, Wood 2008, and Chattopadhyay et al. 2013. 3 = Present in Cupal-Magaña
918et al. 2010. 4 = Present in Caldicott et al., 2005 and Westaway et al., 2011. s s s s s s s s s t e e e e n n n i w i r r r o o o P c o o u u r ti ti ti e t t c r c c c c c p S u e e e a S n F s s s r i i i u F r r P B T d a u Q
Alligator X X X X X X mississippiens is
Alligator X X X X X sinensis
Caiman X X X crocodilus
Caiman X X latirostris
Caiman X X X X yacare
Crocodylus X X X X 3 acutus
Crocodylus X X intermedius
Crocodylus X X X X johnstoni
Crocodylus X X X mindorensis
Crocodylus X X X moreletii
Crocodylus X 1 X X 4 niloticus
Crocodylus X X X X X novaeguineae Drumheller and Brochu | 49
Crocodylus X X X 2 2 porosus
Crocodylus X X X rhombifer
Crocodylus X X siamensis
Mecistops X X cataphractus
Melanosuchu X X X s niger
Osteolaemus X X X tetraspis
Paleosuchus X palpebrosus
Paleosuchus X X trigonatus
Tomistoma X X X X X schlegelii
920TABLE 2 —Detailed results of the statistical analyses performed to test the independence of
921subscore expression from the listed variables. Abbreviations: SS = sum of squares, d.f. = degrees
Chi-squared Tests n d.f. Chi-square p-value
Bone type (pig vs. cow) 60 33 24.99 0.840
Sex (male vs. female) 50 31 19.992 0.936
Origin (captive vs. wild) 46 20 14.954 0.779
Protocol (restrainted vs. not) 59 42 28.267 0.948
Snout ecomorph (Brochu, 2001) 61 36 41.487 0.244 Drumheller and Brochu | 50
ANOVA Tests n SS (between groups) SS (within groups) F p-value
Age in years 42 17.1905 5190.71 0.1325 0.718
Total length in cm 54 138.924 377390 0.01914 0.891
Head length in cm 54 0.653432 6753.01 0.005032 0.944
Snout-vent length in cm 54 38.5195 94477.9 0.0212 0.885
Mass in kg 49 233.915 155328 0.07078 0.791
Kruskal-Wallis Tests Shapiro-Wilk W Shapiro-Wilk p-value Kruskal-Wallis p-value
Age in years 0.9088 0.003 0.431
Total length in cm 0.9024 0.0003 0.893
Head length in cm 0.9223 0.002 0.979
Snout-vent length in cm 0.9425 0.012 0.830
Mass in kg 0.7358 4.83E-08 0.992
927TABLE 3 —Literature addressing fossil bite marks associated with crocodyliforms that were not
928included in the phylogenetic analysis. Data presented includes (from left to right): paper citation,
929acting taxon, marked taxon, geologic age, method of associating marks with actors.
Citation Acting taxa Marked Taxa Age Notes Boyd et al., 2013 Crocodyliformes Hypsilophodontid Cretaceou Bisected pit, s embedded tooth Noto et al., 2012 Crocodyliformes, Turtle, Hadrosaur Cretaceou Bisected marks, n. sp. s serial marks Casal et al., 2013 Crocodyliformes Aniksosaurus Cretaceou Bisected marks, Drumheller and Brochu | 51
darwini s hook scores, serial marks, interdental spacing Gianechini and de Crocodyliformes? Buitreraptor Cretaceou Mark shape, Valais, 2015 gonzalezorum s distribution Botfalvai et al., 2014, “Allodaposuchus- bothremydid Cretaceou Bisected marks, 2015 like” turtle, s size, interdental Crocodyliformes Iharkutosuchus spacing Martin, 2013 Dyrosauridae or Dyrosauridae Paleocene Mark size, shape, Eusuchian association Milàn et al., 2011 Crocodylia Chelonionid turtle Paleocene Round mark shape Evgen et al., 2012 Crocodylia indet. Cheloniidae indet. Eocene Comparison to Noto et al., 2012 Davidson and Solomon, Crocodylus Homo habilis Plio- Comparison to 1990 Pleistocen modern actors, e excluded other possible actors Fuentes, 2003 Asiatosuchus Neochelys Eocene Comparison to dentition of possible actors, association Mead et al., 2006 Crocodylus Horse, Turtle Plio- Round mark shape, Pleistocen association e Mikulás et al., 2006 Crocodylus? Many different Miocene Comparison to vertebrates tooth shape Steadman et al., 2007; Crocodylus Turtle Holocene Round mark shape, Morgan and Albury, rhombifer association 2013 Cisneros, 2012 Crocodylus acutus Proboscidean Pleistocen Round mark shape, e interdental spacing Buffetaut, 1983 Tilemsisuchus Tilemsisuchus Eocene Interdental spacing, lavocati lavocati mark locations Erickson, 1984 Leidysuchus Turtle Paleocene Mark size, formidabilis interdental spacing, association Williamson, 1996 ?Brachychampsa ?Brachychampsa Cretaceou Bite mark shape sealetyi sealetyi s and location Karl and Tichy, 2004 Phosphatosaurus Palaeomedusa? Eocene Comparison to gavialoides dentition, association Katsura, 2004 Toyotamaphimeia Toyotamaphimeia Pleistocen Bite mark shape machikanensis machikanensis e and location Hastings et al., 2015 Anthracosuchus Turtle Paleocene Mark size, balrogus association Mackness et al., 2010 Pallimnarchus Pallimnarchus Pliocene Mark size, pollens pollens association 930
931 Drumheller and Brochu | 52
932 SUPPLEMENTARY MATERIAL
933SUPPLEMENTARY FIGURE 1 —Eusuchian phylogeny, generated from a matrix of 189 characters
934and including 124 ingroup taxa. Solid lines represent the strict consensus tree. Dotted lines
935indicate areas in which the topology differs in the Adams consensus tree. Drumheller and Brochu | 53
936 Drumheller and Brochu | 54
937SUPPLEMENTARY TABLE 1 —Vital statistics and collection protocols for sampled specimens;
938abbreviations: Y = yes; N = no; M = male; F = female; C = captive; W = wild; n/a = non-
939applicable/unrecorded. t s h # h s n
t t n e n t s g n e g d o l n i s v e o h n o e n i t i i - i e e p x e g e t g t c t g c s l i l g e i c a
u e s e o m e s a r l e s d e o a p n m o a - s w a c s s i t n i d e c s o b a t a h u h t q g n
Alligator 22Y, e 185 l mississippiensis - 970 pi 11M, 314 45 161 .97 American Alligator 62 Y g M 23D cm cm cm kg C N N unrestrained
co 143 990 w 296 41 151 .6 13 ? M ~31Y cm cm cm kg ? N N unrestrained
co 31. A05 w 244 5 120 001 ? M adult cm cm cm ? ? N N unrestrained
A01 co 402 57 193 025 Y w M >56 cm cm cm ? W Y N unrestrained
5Y, 15. 62. A00 pi 11M, 122 25 25 7.8 241 g ? 5D cm cm cm kg C N N restrained
6Y, 185 25. 95. 25. 991 pi 10M, .5 5 25 4 06 Y g ? 9D cm cm cm kg W Y N restrained
5Y, 73. 12. A00 pi 11M, 146 19 5 6 268 Y g ? 5D cm cm cm kg C N N restrained
971 304 41 158 unrestrained 03 M adult cm cm cm ? ? N N with 97064
22Y, 45. 970 co 11M, 353 5 169 unrestrained 64 Y w M 24D cm cm cm ? C N N with 97103
Fluf co fy Y w M adult ? ? ? ? ? N N unrestrained
Wal co ly Y w ? adult ? ? ? ? ? N N unrestrained
Mot Y co F adult ? ? ? ? ? Y N unrestrained Drumheller and Brochu | 55
402 643 co 18 Y w ? adult ? ? ? ? ? N N unrestrained
tt 20. 105 14. 008 pi juveni 160 5 .5 8 52 g ? le cm cm cm kg ? Y N restrained
19Y, 18. 14. Alligator sinensis - 860 pi 9M, 155 8 81 6 Chinese Alligator 52 Y g M 15D cm cm cm kg C N N restrained
19Y, 17. 11. 860 pi 9M, 141 5 74 8 53 Y g F 15D cm cm cm kg C Y N restrained
10Y, 136 16. 74. 13. 950 pi 9M, .9 1 3 5 74 Y g F 1D cm cm cm kg C Y N restrained
13Y, 881 pi 9M, 106 14 55 3.5 30 Y g F 14D cm cm cm kg C N Y restrained
21. Caiman crocodilus - 960 pi 164 5 98 25 Spectacled Caiman 54 Y g M adult cm cm cm kg ? Y N restrained
no pi tag Y g ? ? ? ? ? ? ? Y N restrained
104 321 pi 089 Y g ? ? ? ? ? ? ? N N restrained
Caiman latirostris - 20Y, Broad-snouted 860 pi 5M, 179 21 99 27 N Caiman 12 Y g F 7D cm cm cm kg C ? N restrained
9Y, 21. 26. 891 pi 11M, 159 5 87 2 25 Y g F 10D cm cm cm kg C N N restrained
16Y, 152 88. 22. Caiman yacare - 960 pi 10M, .5 20 5 7 Yacare Caiman 28 Y g F 2D cm cm cm kg C N N restrained
18Y, 21. 890 pi 6M, 148 3 91 19 38 Y g F 21D cm cm cm kg C Y Y restrained Drumheller and Brochu | 56
18Y, 60. 890 pi 6M, 5 7.5 30 39 Y g F 21D cm cm cm ? C N N restrained
10Y, 18. 63. Crocodylus acutus - 960 co 3M, 117 5 5 5.6 American Crocodile 49 Y w ? 9D cm cm cm kg C Y N restrained
33Y, 40. 150 90. A03 co 6M, 287 5 .5 8 048 Y w F 23D cm cm cm kg C N N unrestrained
Crocodylus 18Y, 312 173 intermedius - 912 co 11M, .5 44 173 .25 Orinoco Crocodile 77 Y w M 22D cm cm cm kg C N N unrestrained
Crocodilus johnsonii 27Y, 19. - Johnston's A04 pi 7M, 118 5 66 5.2 Crocodile 003 g? F 0D cm cm cm kg C N N restrained
36. 970 pi 217 35 118 3 16 Y g M adult cm cm cm kg ? N N restrained
27Y, 87. 11. 930 pi 7M, 157 27 5 8 42 Y g F 7D cm cm cm kg C N N restrained
27Y, A04 pi 7M, 132 23 75 7.8 004 Y g F 7D cm cm cm kg C Y Y restrained
Crocodilus 4Y, 11. 45. mindorensis - A03 pi 10M, 85 5 5 2.2 Philippine Crocodile 034 g ? 9D cm cm cm kg C restrained
4Y, 36. A03 pi 10M, 69 9.5 5 1.2 036 Y g ? 9D cm cm cm kg C Y N restrained
4Y, A03 pi 10M, 70 9.5 39 1.4 033 Y g F 9D cm cm cm kg C N N restrained
43Y, 37. 108 Crocodylus moreletii 990 co 6M, 284 5 154 .9 - Morelet's Crocodile 09 Y w M 20D cm cm cm kg W N N unrestrained
8Y, Crocodylus niloticus A01 pi 0M, 122 15 62 7 - Nile Crocodile 027 Y g ? 13D cm cm cm kg C N N restrained Drumheller and Brochu | 57
239 135 86. 932 co .5 36 .5 5 20 Y w M adult cm cm cm kg ? Y N unrestrained
25Y, 37. 93. 990 co 1M, 261 5 134 3 14 Y w M 4D cm cm cm kg ? N N unrestrained
Crocodylus 6Y, 116 17. novaeguineae - New A05 pi 0M, .5 5 64 6.7 Guinea Crocodile 013 g? M 28D cm cm cm kg C restrained
6Y, A05 pi 0M, 97 15 53 3.4 009 g? F 28D cm cm cm kg C restrained
6Y, A05 pi 0M, 104 16 56 3.8 006 Y g F 28D cm cm cm kg C Y N restrained
6Y, 12. A05 pi 0M, 82 5 40 3.8 012 g? M 28D cm cm cm kg C restrained
290 33. 149 unrestrained, A05 co .5 75 .5 123 tooth broken 004 Y w M adult cm cm cm kg W N Y (top, left, front)
Crocodylus palustris n/ n/ n/ n/ n/ n/ - Mugger n/a a a a n/a n/a n/a n/a n/a a a a edentulous
Crocodylus porosus - Salt Water San co Crocodile dy w F ? ? ? ? ? C N N unrestrained
Crocodylus 17Y, 111 rhombifer - Cuban 890 co 4M, 209 27 .5 63 Crocodile 33 Y w F 17D cm cm cm kg C Y N restrained
14Y, 186 24. 98. 29. tooth broken 913 co 7M, .5 5 5 5 (bottom, right, 00 Y w F 1D cm cm cm kg C Y N middle)
Crocodilus 36. 86. siamensis - Siamese 912 pi 263 5 139 6 Crocodile 73 Y g M adult cm cm cm kg W N N unrestrained
5Y, A00 pi 10M, 124 17 62 4.2 104 g? F 26D cm cm cm kg C N N restrained
Gavialis gangeticus - n/a n/ n/ n/ n/a n/a n/a n/a n/a n/ n/ n/ stressed by Indian Gharial a a a a a a enclosure, off Drumheller and Brochu | 58
Mecistops cataphractus - 11Y, Slender-snouted 960 pi 9M, 118 20 63 4.8 Crocodile 12 Y g F 3D cm cm cm kg C N N restrained
11Y, 960 pi 9M, 115 18 51 3.8 15 Y g F 1D cm cm cm kg C N N restrained
Melanoshuchus 303 46. niger - Black 912 co .5 35 5 143 Caiman 66 Y w F adult cm cm cm kg W Y N unrestrained
Osteolaemus 182 23. 34. tetraspis - African 960 pi .5 5 102 6 Dwarf Crocodile 79 Y g M adult cm cm cm kg ? N N restrained
24Y, 14. 940 pi 9M, 135 18 74 4 04 g F 9D cm cm cm kg C N N unrestrained
7Y, 17. 69. 990 pi 2M, 124 8 3 9.4 04 Y g F 20D cm cm cm kg C N N restrained
Paleosuchus 15Y, 125 12. palpebrosus - Dwarf 930 pi 11M, .5 17 71 2 Caiman 72 g? M 24D cm cm cm kg C N N restrained
15Y, 18. 14. 930 pi 11M, 136 5 77 6 71 Y g M 24D cm cm cm kg C N N restrained
15Y, 15. 930 pi 11M, 123 5 66 9.5 73 Y g M 24D cm cm cm kg C N N restrained
Paleosuchus 20Y, 64. trigonatus - Smooth- 850 pi 9M, 170 26 99 5 fronted Caiman 29 Y g M 19D cm cm cm kg C Y N unrestrained
6Y, 15. 870 pi 5M, 139 21 82 4 28 Y g F 23D cm cm cm kg C Y N unrestrained
2Y, 19. A04 pi 1M, 154 23 89 1 tooth broken 031 Y g M 22D cm cm cm kg C N N (top, right, front)
850 Y pi M adult 160 24. 99. 28 W N N restrained 28 g cm 8 9 Drumheller and Brochu | 59
cm cm kg
Tomistoma 33Y, 40. 150 90. schlegelii - False A01 co 6M, 287 5 .5 8 Gharial 020 Y w F 17D cm cm cm kg W N N unrestrained
404 212 252 912 co .5 51 .5 .5 83 Y w M adult cm cm cm kg W Y N unrestrained