Tooth Marks Research Articles

Zooarchaeology and Taphonomic Aspects of Later Stone Age Faunal Assemblage from Loiyangalani Site in Serengeti National Park, Tanzania

The paper presents detailed zooarchaeological and taphonomic results on the Later Stone Age (LSA) faunal assemblage. The contributions of various taphonomic agents in the formation of the assemblage are accentuated. The assemblage is well-preserved and the majority of specimens are not highly weathered. Fluvial disturbance did not play a significant role and can be ruled out as a significant taphonomic agent in the formation. Results indicate that LSA humans exploited high-quality nutritional resources mainly of the large-sized animals and aquatic resources as extra sources of meat and fat. The assemblage preserves stone tools butchery marks (cut marks and percussion marks) and carnivore marks (tooth marks) albeit few. Overall, the faunal assemblage exhibits high anthropogenic inputs and marginal carnivore involvement.
 Keywords: Zooarchaeology; Taphonomy; Later Stone Age; Serengeti National Park; Loiyangalani; Tanzania

3D Insights into the Effects of Captivity on Wolf Mastication and Their Tooth Marks; Implications in Ecological Studies of Both the Past and Present.

Simple SummaryRecent years have seen major advances in the analysis of carnivore modifications to bone during feeding, based on the integration of 3D modeling and data science techniques, and with special attention being paid to tooth marks. From this perspective, carnivore tooth scores and pits have slowly converted into a protagonist in the identification of the carnivores producing them. The present study confronts the intra-species variability of tooth mark morphologies produced by Iberian wolves, taking into account not only different populations but also whether wild and captive wolves produce different shaped tooth marks. Here we show how, in the case of tooth scores, differences are notable and should thus be treated with caution. Further conclusions reveal that carnivore tooth pits are currently the most diagnostic elements for the study of carnivore feeding traces on bone, pending future studies that compare closely related taxa with sufficient intraspecific variability. In light of this, further investigation into the possible stress captivity may cause on these animals could be of great importance for both the study of past and present. If differences were to exist, these results could implicate a larger margin of error than previously perceived for some experimental samples, affecting both prehistoric and modern-day ecological studies.Human populations have been known to develop complex relationships with large carnivore species throughout time, with evidence of both competition and collaboration to obtain resources throughout the Pleistocene. From this perspective, many archaeological and palaeontological sites present evidence of carnivore modifications to bone. In response to this, specialists in the study of microscopic bone surface modifications have resorted to the use of 3D modeling and data science techniques for the inspection of these elements, reaching novel limits for the discerning of carnivore agencies. The present research analyzes the tooth mark variability produced by multiple Iberian wolf individuals, with the aim of studying how captivity may affect the nature of tooth marks left on bone. In addition to this, four different populations of both wild and captive Iberian wolves are also compared for a more in-depth comparison of intra-species variability. This research statistically shows that large canid tooth pits are the least affected by captivity, while tooth scores appear more superficial when produced by captive wolves. The superficial nature of captive wolf tooth scores is additionally seen to correlate with other metric features, thus influencing overall mark morphologies. In light of this, the present study opens a new dialogue on the reasons behind this, advising caution when using tooth scores for carnivore identification and contemplating how elements such as stress may be affecting the wolves under study.

A Novel Precise Optical Navigation System for Craniomaxillofacial Surgery Registered With an Occlusal Splint.

Background:An augmented reality tool allows visual tracking of real anatomical structures and superimposing virtual images, so it can be used for navigation of important structures during surgery.Objectives:The authors have developed a new occlusal splint-based optical navigation system for craniomaxillofacial surgery. In this study, the authors aim to measure the accuracy of the system and further analyze the main factors influencing precision.Methods:Ten beagle dogs were selected and a three-dimensional model was established through computed tomography scanning, dental model making, and laser scanning, and then registration was performed according to the tooth marking points. The bilateral mandibular osteotomy was performed on Beagle dogs under navigation system based on the occlusal splint. The left side was taken to compare the deviation between the preoperative plan and the surgical results, and the accuracy of distance and angle and the stability of the system were analyzed.Results:The average position deviation between the preoperative design and intraoperative navigation was: 0.01 ± 0.73 mm on the lateral height of the mandibular ramus, 0.26 ± 0.57 mm on the inner height of the mandibular ramus, and 0.20 ± 0.51 mm on the osteotomy length. The average angle deviation is 0.94° ± 1.38° on the angle between the mandibular osteotomy plane and ramus plane and 0.66° ± 0.97° on the angle of the retained mandibular angle. And most of the data showed good consistency.Conclusions:In summary, the accuracy of the system can meet clinical requirements and can be used as a useful tool to improve the accuracy of craniomaxillofacial surgery.

Rare evidence for ‘gnawing-like’ behavior in a small-bodied theropod dinosaur

Mammalian carnivores show a higher degree of prey bone utilization relative to non-avian theropod dinosaurs, with this major ecological difference reflected in the frequency and morphology of tooth marks in modern and Cenozoic assemblages relative to Mesozoic ones. As such, prey bone utilization (i.e., gnawing, bone-breaking, osteophagy) may represent a key ecological strategy repeatedly exploited by mammalian carnivores but rarely in theropod dinosaurs. Here we describe an isolated adult-sized hadrosaurid pedal ungual (III-4) from the Dinosaur Park Formation (Campanian) of southern Alberta which shows a unique pattern of bite marks from a small- to medium-sized theropod dinosaur. Thirteen distinct tooth marks occur in a restricted area of the ungual, and the pattern suggests up to six repeated, high-power bites delivered to the bone. The tracemaker cannot be definitively identified, but was likely a dromaeosaurid or very young tyrannosaurid. Tooth marks on at least four other Dinosaur Park Formation hadrosaur pedal unguals are reported, but the overall frequency of occurrence in unguals (< 1%) is much lower than that reported for other bones. The pattern of tooth marks on this specimen deviates from most described theropods tooth marks, and given the low volume of meat associated with the ungual, may represent theropod prey bone utilization as part of late-stage carcass consumption, and a behavior similar to mammalian gnawing.

Revisiting the mammoth bone modifications from Bluefish Caves (YT, Canada)

The long-debated mammoth bone “core” and “flake” recovered from the Pleistocene loess deposit of Bluefish Cave 2 (Yukon Territory, Canada) and previously described by Cinq-Mars and Morlan (1999) are re-analyzed from a full zooarchaeological and taphonomic perspective. The core and flake are characterized by an absence of carnivore tooth marks and the presence of fresh fracture patterns and two striae potentially attributed to cultural activities. After rejection of several hypotheses involving natural causes, we state that humans were more likely responsible for the bone modifications and we support the hypothesis that a proboscidean bone technology may have been present in eastern Beringia (Alaska/Yukon Territory) sometime between ca. 28,000 and 16,000 years BP.

Shark–seal interaction off South Africa’s west coast during the early Pliocene (5 Ma) (with corrigendum)

A study of the Mio-Pliocene marine palaeoenvironment on South Africa’s west coast revealed aspects of the biology and behaviour of fossil marine mammals. Close examination showed that seals from Langebaanweg suffered from pathologies and bore marks of marine carnivore activity. This study adds to our knowledge of shark feeding behaviour in the geological past and is one of a few studies of sharks feeding on seals in the fossil record. Two incomplete seal humeri with shark tooth marks are the first documented evidence from South Africa’s Mio-Pliocene of such behaviour. These injuries show no healing, which suggests that the animals were most likely scavenged.Significance:&#x0D; &#x0D; Fossil rich deposits at Langebaanweg contribute to the knowledge of South African Mio-Pliocene fossils by placing them in a global context.&#x0D; This study is one of five globally that have documented marine carnivores feeding on seals.&#x0D; This is the first description of white sharks feeding on seals from South Africa’s geological past.&#x0D; This study shows this behaviour was in place on South Africa’s coast as early as 5 million years ago.&#x0D; The injuries show no signs of healing, suggesting the most parsimonious explanation is that white sharks were scavenging seal carcasses.&#x0D;

A weakly supervised tooth‐mark and crack detection method in tongue image

AbstractTongue diagnosis is one of the primary clinical diagnostic methods in Traditional Chinese Medicine. Recognizing the tooth‐marked tongue and the crackled tongue plays an essential role in evaluating the status of patients. Previous methods mainly focus on identifying whether a tongue image is a tooth‐marked tongue (cracked tongue) or not, while cannot provide more details. In this study, we propose a weakly supervised method for training the tooth‐mark and crack detection model by leveraging fully bounding‐box level annotated and coarse image‐level annotated tongue images. The proposed model is extended from the YOLO object detection model, and we add several classification branches for recognizing the tooth‐marked tongue and cracked tongue. The classification branch aims to predict the coarse label for both coarse‐labeled data and fully annotated data. The detection branch is used to locate the position of tooth marks and cracks from the fully annotated data. Finally, we utilize a multitask loss function for training the model. Experimental results on a challenging tongue image dataset demonstrate the effectiveness of our proposed weakly supervised method.

The tongue features associated with chronic kidney disease.

Background:Traditional Chinese medicine (TCM) tongue diagnosis plays an important role in differentiation of symptoms because the tongue reflects the physiological and pathological condition of the body. The automatic tongue diagnosis system (ATDS), which noninvasively captures tongue images, can provide objective and reliable diagnostic information. Chronic kidney disease (CKD) currently is an important global public health problem and contributor to morbidity and mortality from non-communicable diseases. Thus, it is interesting to analyze and probe the relationship between tongue examination and CKD.Methods:This protocol is a cross-sectional, case-controlled observational study investigating the usefulness of the ATDS in clinical practice by examining its efficacy as a diagnostic tool for CKD. Volunteers over 20 years old with and without CKD will be enrolled. Tongue images will be captured and the patients divided into 2 groups: CKD group and healthy group. Nine primary tongue features will be extracted and analyzed, including tongue shape, tongue color, tooth mark, tongue fissure, fur color, fur thickness, saliva, ecchymosis, and red dots.Result:The results of this study will systematically evaluate tongue manifestations of patients and examine its efficacy as an early detection and diagnosis of CKD.Discussion:The aim of this protocol is to investigate discriminating tongue features to distinguish between CKD and normal people, and establish differentiating index to facilitate the noninvasive detection of CKD.Trial registries:ClinicalTrials.gov; Identifier: NCT04708743.

A 3D taphonomic model of long bone modification by lions in medium-sized ungulate carcasses

Here, we present the first three-dimensional taphonomic analysis of a carnivore-modified assemblage at the anatomical scale of the appendicular skeleton. A sample of ten carcasses composed of two taxa (zebra and wildebeest) consumed by wild lions in the Tarangire National Park (Tanzania) has been used to determine element-specific lion damage patterns. This study presents a novel software for the 3D spatial documentation of bone surface modifications at the anatomical level. Combined with spatial statistics, the present analysis has been able to conclude that despite variable degrees of competition during carcass consumption, lions generate bilateral patterning consisting of substantial damage of proximal ends of stylopodials and zeugopodials, moderate damage of the distal ends of femora and marginal damage of distal ends of humeri and zeugopodials. Of special interest is, specifically, the patterning of tooth marks on shafts according to element, since these are crucial to determine not only the type of carnivore involved in any given bone assemblage, but also the interaction with other agents (namely, hominins, in the past). Lions leave few tooth marks on mid-shaft sections, mostly concentrated on certain sections and orientations of stylopodials and, to a lesser extent, of the proximal tibia. Redundant occurrence of tooth marks on certain bone sections renders them as crucial to attest lion agency in carcass initial consumption. Indirectly, this can also be used to determine whether hominins ever acquired carcasses at lion kills.

САНІТАРНЕ ЗАХОРОНЕННЯ НА ПІВДЕННОМУ ГОРОДИЩІ ВОЗВЯГЕЛЯ. РЕКОНСТРУКЦІЯ ОБСТАВИН ЗА АНТРОПОЛОГІЧНИМИ ДАНИМИ

Моменти смерті та поховання людини є ключовими у танатологічних та антропологічних дослідженнях. Перимортальні й посмертні процеси змінюють макро- і мікроструктуру кістки й часто призводять до її руйнування. Зазвичай вважають, що кістки поганої збереженості є малоінформативними в антропології. Однак у судовій медицині та археології ступінь та особливості «поганої збереженості» є основним і чи не єдиним джерелом інформації про час, умови, причини загибелі та обставини поховання.&#x0D; У 1993 р. під час розкопок Південного городища Возвягеля (Новоград-Волинський) було виявлено скупчення людських і тваринних кісток у підкліті будівлі (будинок ювеліра), датованої давньоруським часом. Людські кістки було передано для антропологічного аналізу. Оскільки скупчення являло собою «костище», у дослідженні використовували такі самі методики, що й у антропології полів битв.&#x0D; Статтю присвячено дослідженню перимортальних і посмертних маркерів на кістках для з’ясування обставин загибелі людей, умов перебування останків після смерті та часу їх захоронення. &#x0D; У статті проаналізовано основні тафономічні макроскопічні маркери на людських кістках. Наявність можливих перимортальних травм і статево-віковий профіль групи захоронених людей свідчить про загибель звичайного населення городища внаслідок військового конфлікту. Кістки більшої частини скелетів у скупченні лежать не в анатомічному порядку. Зважаючи на цей факт, а також на стан кісткової тканини та поверхні кісток, наявність слідів зубів тварин та інші ознаки, можна припустити, що скупчення утворилось через 1–9 місяців після загибелі людей. Скупчення є санітарною ямою і належить до навмисних захоронень. Із певною часткою ймовірності його можна пов’язати з каральною експедицією Данила Галицького у Болоховські землі, яка відбулась улітку–восени 1256 р.&#x0D; У статті також запропоновано класифікацію поховань і захоронень, на основі їх локалізації, морфології, первинності та інших критеріїв

Deep learning classification of tooth scores made by different carnivores: achieving high accuracy when comparing African carnivore taxa and testing the hominin shift in the balance of power

The balance of power (that is the dominance on the predation arena between carnivore competitors and hominins) remains controversial. One reflection of this is the carnivore modification of hominin bones. During human evolution, hominins were first prey and then predators of other animals, including carnivores. Modifications reported on some hominin bones could result from primary predators feeding on them or post-depositional modifications by scavengers. Determining carnivore agency would be crucial to interpret such information. Here, a series of computer vision models based on convolutional neural networks is presented, comparing five different types of carnivores jointly and then pairwise. It is shown how such models contain different heuristics regarding specific carnivore taxa, which regarding tooth marks made by lions and spotted hyenas can be accurately classified by as much as 92% of the testing set. The present study also shows the potential of transfer knowledge in building accurate classification of images and for taphonomic interpretation. The application to tooth marking on a 500 ka hominin femoral shaft indicates that by that time, carnivore modifications of human remains may have resulted from post-depositional scavenging rather than by predation.

AN IMPORTED CASE OF TYPHOID FEVER IN CHUVASHIA

Typhoid fever and paratyphoids are still a widespread topical problem, especially in connection with the possibility of imported cases from regions that are epidemically disadvantaged by the disease. The current relevance of typhoid fever problem in the Russian Federation is determined by its persistent sporadic morbidity. Reduced control over the sanitary and hygienic state of the environment, deterioration of the quality of water treatment in water supply and sewerage systems, and a number of other reasons can still result in an increase in the number of patients with typhoid-paratyphoid diseases. At the same time, a mild and subtle course of typhoid fever is a common cause of late disease diagnosis and late start of the patient's treatment. Methods of modern diagnosis and treatment of typhoid-paratyphoid disease are considered. The article describes a case of typhoid fever that was diagnosed in the Chuvash Republic in 2017 after a long period of epidemiological welfare. The aim of the study is to analyze an imported case of typhoid fever and characterize the current course of the disease in the period of sporadic morbidity. A retrospective analysis of the patient's history of typhoid fever was performed. The diagnosis was made on the basis of clinical, epidemiological and laboratory data. To confirm the diagnosis of typhoid fever, bacteriological methods to study blood, urine and feces were used. The study of this female patient's medical history showed that there were no typical symptoms characteristic of typhoid fever: subcutaneous fat was moderately expressed, on palpation submandibular lymph nodes were painless, mobile, of soft-elastic consistency up to 0.6 cm. Nasal breathing was not disturbed, breathing was vesicular, the RR was 16 movements per 1 min., heart tones were muted, rhythmic, the heart rate was 100 beats / min, BP – 120/75 mm Hg, temperature – 39°C. The tongue was dry, coated with a grayish-brown plaque with tooth marks on the edges. The pharynx was moderately hyperemic. The stomach was soft, painless, the liver and the spleen were not enlarged, Padalka’s symptom was negative. The patient reported fecal excretion with a tendency to constipation. There was no CVA tenderness on both sides. Thus, it is difficult to make a diagnosis of typhoid fever with sporadic morbidity. Modern clinical presentation of typhoid fever in moderate severity differs from the classic one. The patient had an atypical course of typhoid fever. Typhoid status was absent. The cutaneous coverings were normal, there was no rash. There was no congestive splenomegaly or Padalka's symptoms. No complications or relapses developed. The diagnosis was made only when the pathogen was seeded from the blood (hemoculture) and basing on clear epidemiological data.

Tooth-Marked Tongue Recognition Based on Mask Scoring R-CNN

Tooth-marked tongue is one of the important tongue features in Traditional Chinese Medicine tongue diagnosis. It reflects the dysfunction of liver, spleen and kidney, and contains rich pathological information. However, the recognition of tooth-marked tongue is challenging. Most existing methods only focus on the classification of tooth-marked tongue, and the exact location and number of teeth marks were not involved, which had no great practical significance for the subsequent treatment based on syndrome differentiation. In this paper, we try to solve these problems by proposing a method based on Mask Scoring R-CNN framework and transfer learning which can extract, visualize the teeth marks and identify the number of teeth marks. First, the tongue image is fed into residual network of depth 101 layers (ResNet-101) to generate regions of interest (RoIs) via region proposal network (RPN) and RoI feature via RoIAlign. Next, MaskIOU is then predicted using the predicted mask and RoI characteristics as inputs. The proposed approach achieved F1 score of 0.95. According to these experimental results, the approach can robustly detect and segment teeth marks, which can provide a basis for the severity analysis of tooth-marked tongue.

Dermatological Manifestations in Patients of Chronic Kidney Disease (CKD)

Background: CKD is associated with various mucocutaneous manifestations that impair the quality of life.The objective was to study the incidence of various cutaneous manifestations in CKD patients.Materials and Method: 130 (M:F = 4.2:1) patients aged 15?78 (Mean age- 50.32 years) having CKDfor 3 month to 5 years were studied for mucocutaneous manifestations. Forty (30.7%) patients were onhemodialysis for 1-3 months. Detailed medical history, clinical and mucocutaneous examination and labinvestigations were performed. KOH mounts, skin biopsy, Gram’s and Giemsa staining, bacterial or fungalcultures were performed as required.Results: Xerosis in 104 patients (80%), skin pallor in 76(58.4%), pruritus in 52 (50.9%) patients, pigmentationin 45(34.6%) and purpura in 12 (9.2%) patients were the major dermatoses. Perforating folliculitis occurredin1 (0.76%) patient..Mucosal findings included coated tongue in14(11.66%), xerostomia in 11(9.16%) andmacroglossia with teeth markings and fissured tongue in 9 (7.5%) patients each, angular cheilitis in 3 (2.5%),and aphthous stomatitis and black pigmented tongue in 1 (0.83%) patients each. Hair abnormalities includedsparse scalp and body hairs in 43 (33%), 11 (8.4%), respectively and lusterless hair in 22 (16.9%) patients.Major nail abnormalities were half and half nails or Linday’s nails in 33(25.3%), longitudinal ridging in29(22.3%), leuconychia in 13(10%), onycholysis in 9(6.9%), Beau’s lines in 6(4.6%), koilonychias in4(3.07%), Mee’s lines in 1(0.76%) and Meuhrcke’s lines in 1(0.76%).Conclusions: Xerosis, pruritus, skin pallor/pigmentary changes, half and half nails, longitudinal ridging,discoloration, sparse hairs, coated tongue, xerostomia, macroglossia, and infections were the most commonmucocutaneous manifestations in the studied patients irrespective of hemodialysis status.

The effects of prey size on carnivore tooth mark morphologies on bone; the case study of Canis lupus signatus

ABSTRACT Carnivore feeding behaviour is a valuable line of research of increasing value in taphonomic analyses. An interesting component of these studies lies in the differentiation of carnivore activity based on tooth marks left on bone. Among the methodological approaches available, a major protagonist in recent years has been the incorporation of hybrid geometric morphometric studies with artificially intelligent algorithms, reaching over 95% accuracy in some cases. In spite of this recent success, a number of methodological questions are still to be answered for wide scale application of these techniques into other applied fields of science. One of these questions lies in the possible variability induced by prey size on tooth mark morphologies. Here we compile data regarding these effects, using the Iberian wolf as a relevant case study in both contemporary and prehistoric European and North American ecology. The methodology employed opens new questions regarding carnivore tooth marks that should consider the effects of mastication biomechanics. While in most cases prey size is not a significant conditioning factor, caution is advised for future experimentation when considering small prey where some statistical noise may be present. Nevertheless, future experimentation into other carnivore case studies can be considered a valuable research goal.

African elephant bones modified by carnivores: Implications for interpreting fossil proboscidean assemblages

Carcasses of African savanna elephants (Loxodonta africana africana) are affected by large and small carnivores which mark, move, break, and subtract bones. Bone-gnawing scavengers modify proboscidean carcasses and individual bones in patterned sequences. We summarize how scavengers modify major skeletal elements in stages which may reflect the extent of carcass utilization. The stages of modification also may be detectable in fossil proboscidean assemblages, which would potentially strengthen ecological interpretations of assemblage origins. We discuss the significance of tooth marking and breakage of bones, different bone-gnawing behaviors, variations in intensity of gnawing, and the effects of increasingly worn carnivore teeth. We demonstrate that tooth marks made by carnivores which are habitual bone-gnawing scavengers have substantially different sizes from tooth marks made by conspecifics with less worn teeth, an unexplored complication when attempting to identify taxon of scavenging carnivores in fossil proboscidean assemblages. Herein we provide a guide for identifying carnivore effects on proboscidean bones, which may partially or wholly reduce analysts’ variability in reporting frequencies of carnivore modifications in fossil proboscidean assemblages.

Corrigendum to ‘Deep learning improves taphonomic resolution: high accuracy in differentiating tooth marks made by lions and jaguars'

Corrigendum to ‘Deep learning improves taphonomic resolution: high accuracy in differentiating tooth marks made by lions and jaguars'

Generation Mechanism and Quality of Milling Surface Profile for Variable Pitch Tools Considering Runout

Abstract Surface profile is one of the foremost aspects to evaluate milling performance. Its generation mechanism is affected by a variety of factors such as tool geometry, runout values, and process parameters and thus still deserves further investigation. This paper aims to propose a unified method to study the surface generation mechanism and to predict the machining quality for variable pitch tools considering runout. First, a Floquet theory based algorithm is extended to analyze the machining stability and output the dynamic responses of the machining system. The resultant trajectories of cutting edges are obtained by kinematic synthesis of system vibrations, tool rotations, and machining feed. Next, both the surface location error (SLE) and the surface roughness are simultaneously extracted from the edge trajectories. A series of cutting tests are performed to validate the prediction results. Some new characteristics of the machined surface profile in terms of form errors and teeth marks are discovered and theoretically explained. Finally, the joint influences of tool geometry, runout values, and process parameters on the surface generation mechanism and quality are analyzed in detail with the proposed method.

A camera trap record of scavengers at a kudu carcass: implications for archaeological bone accumulations

A camera trap was set near a greater kudu bull carcass for 3 weeks at the start of winter. The carcass lay in an open savanna setting on a game farm in Limpopo, and it was visited by leopard, brown hyena, black-backed jackal, African civet, honey badger, bushpig and warthog. At the end of a month there were no visible remains of the carcass save the skull and damaged horns. After a week, when decomposition was pronounced, suids spent more time at the carcass than other animals. They may have been responsible for much of the on-site bone consumption. Bone and meat portions not eaten directly at the death scene were probably carried away by scavengers like brown hyena and jackal. The area was excavated and sieved to collect bone debris that might have been trampled into sediment. Only a few small bone fragments were recovered, one of which had a tooth mark. Several outcomes are of interest to archaeologists. Firstly, the diversity of scavengers at the kudu carcass (including some animals not normally classified as scavengers) suggests that damage on surviving bone at some archaeological sites may be from an assortment of animals not normally considered to be scavengers. Comparative collections must accommodate such variety. Secondly, under certain environmental conditions, death assemblages in the wild may disappear without trace when predators can move freely and feed without disturbance. Thirdly, is possible that some bone fragments survive at archaeological sites because they were protected (possibly unintentionally) by human presence, and because they were on occasion processed in ways that made them less attractive to predators.

Predation of the giant Miocene caiman Purussaurus on a mylodontid ground sloth in the wetlands of proto-Amazonia.

Thirteen million years ago in South America, the Pebas Mega-Wetland System sheltered multi-taxon crocodylian assemblages, with the giant caiman Purussaurus as the top predator. In these Miocene swamps where reptiles and mammals coexisted, evidence of their agonistic interactions is extremely rare. Here, we report a tibia of the mylodontid sloth Pseudoprepotherium bearing 46 predation tooth marks. The combination of round and bisected, shallow pits and large punctures that collapsed extensive portions of cortical bone points to a young or sub-adult Purussaurus (approx. 4 m in total length) as the perpetrator. Other known crocodylians of the Pebas System were either too small at adulthood or had discordant feeding anatomy to be considered. The pattern of tooth marks suggests that the perpetrator attacked and captured the ground sloth from the lower hind limb, yet an attempt of dismembering cannot be ruled out. This discovery from the Peruvian Amazonia provides an unusual snapshot of the dietary preferences of Purussaurus and reveals that prior to reaching its giant size, young individuals might have fed upon terrestrial mammals of about the size of a capybara.