Semi-aquatic Predator Research Articles

Primeiro relato de predação de um jacaré-coroa (Paleosuchus trigonatus) por uma lontra (Lontra longicaudis)

ABSTRACT Lontra longicaudis is a semi-aquatic predator which mainly feeds on fish and crustaceans, but which can opportunistically predate mammals, birds, and reptiles. In the Amazon, this species is sympatric with Paleosuchus trigonatus, one of the smallest species of crocodilians, whose possible means of defense is a very rigid skin, which causes adults to have few predators. Here we report the first documented case of predation of P. trigonatus by L. longicaudis.

Winter Behavior of Juvenile Brown Trout in a Changing Climate: How Do Light and Ice Cover Affect Encounters with Instream Predators?

During winter, stream fishes are vulnerable to semi-aquatic predators like mammals and birds and reduce encounters by being active in darkness or under surface ice. Less is known about the behavior of fishes towards instream piscivorous fishes. Here, we examined how surface ice and light affected the anti-predator behavior of juvenile brown trout (Salmo trutta Linnaeus, 1758) in relation to piscivorous burbot (Lota lota Linnaeus, 1758) and northern pike (Esox lucius Linnaeus, 1758) at 4 °C in experimental flumes. Trout had lower foraging and swimming activity and spent more time sheltering when predators were present than when absent. In daylight, trout’s swimming activity was not affected by predators, whereas in darkness trout were less active when predators were present. Trout consumed more drifting prey during the day when ice was present, and they positioned themselves further upstream when under ice cover, regardless of light conditions. Trout stayed closer to conspecifics under ice, but only in the presence of pike. Piscivorous fishes thus constitute an essential part of the predatory landscape of juvenile trout in winter, and thus loss of ice cover caused by climate warming will likely affect trout’s interactions with predators.

Sources of intraspecific variation in the isotopic niche of a semi-aquatic predator in a human-modified landscape.

Intraspecific variation modulates patterns of resource use by species, potentially affecting the structure and stability of food webs. In human-modified landscapes, habitat disturbance modifies trophic interactions and intraspecific niche variation, impacting population persistence. Here, we investigated the relationship of sex, ontogeny, and habitat factors with the trophic niche of Caiman crocodilus in an agricultural landscape. We evaluated temporal variation in the trophic niche parameters using carbon and nitrogen stable isotope analysis from different body tissues. We found that caimans exploit the same carbon and nitrogen pools through time, with low isotopic variability between seasons, partly due to the slow isotope turnover rates of tissues in crocodilians. Conversely, the trophic niche of caimans varied across habitats, but with no evidence of a difference between natural and anthropogenic habitats. It apparently results from the influence of habitat suitability, connectivity, and caiman movements during the foraging. Our findings highlight the broader niches of juvenile caimans relative to adults, possibly in response of territorialism and opportunistic foraging strategy. Although using similar resources, females had a larger niche than males, probably associated with foraging strategies during nesting. Considering the sex and body size categories, caimans occupied distinct isotopic regions in some habitats, indicating apparent niche segregation. Ontogenetic trophic shifts in the isotopes (δ13C and δ15N) depended on sex, leading to resource partitioning that can potentially reduce intraspecific competition. Decision-makers and stakeholders should consider the trophic dynamics of sex and body size groups for the sustainable management and conservation of caiman populations, which implies in the maintenance of wetland habitats and landscape heterogeneity in the Formoso River floodplain.

Winter Dynamics of Drifting Invertebrates’ Vertical Distribution in a Small Salmon River

The composition of the winter syrton of a small salmon river was dominated by mayfly larvae (Ephemeroptera), dipteran larvae (Diptera), and adult water mites (Hydracarina). The presence of a significant linear dependence of the number of drifters entering the nets on the volume of water filtered by the nets has not been proven, so we used not the syrton density (ind./m3), but the data of actual catches. The vertical distribution of drifting invertebrates of different taxonomic affiliation had its own characteristics. Under conditions of good illumination of the water column, the drift intensity of invertebrates increased in the daytime. This fact is probably indirectly related to the low water temperature, which limits the swimming ability of drift-feeding fish, which because of this become more vulnerable to fish-feeding warm-blooded predators, and therefore in winter during daylight hours lead a predominantly inactive and secretive way of life. In December, most daytime drifters migrated near the surface of the water column, and in January, on the contrary, near the bottom. The latter may be due to the overwhelming effect of lower daytime air temperatures, since until mid-February the riverbed was not completely covered with ice. After a heavy February snowfall, the upper layers of the river flow turned out to be isolated from the effect of air temperature, and the level of illumination of the water column during the day began to correspond to the period of late twilight. As a result, fish became less accessible to warm-blooded semiaquatic predators, the intensity of invertebrate drift in the daylight hours decreased sharply, and the distribution of drifters throughout the water column vertical became fairly uniform.

Mercury concentration in the tissues of the Eurasian otter: a seasonal dependance in Slovakia.

The river otter is considered to be an important bioindicator of water clarity. This study focuses on mercury contamination within this species. Throughout the study, individuals from habitats in the foothills and surroundings of the Liptovská Mara reservoir were analyzed. Twenty-three samples of liver tissue, and twenty-two samples of hair and kidney tissue were collected. Of these samples, the average mercury concentration detected in tissues was 10.6mg/kg in guard hairs; 12.9mg/kg in under hairs; 3.3mg/kg in kidney tissue; and 4.3mg/kg in liver tissue. Analysis of certified reference material (ERM-BB186-Pig Kidney) was used to assist in the development of an accurate method for total mercury determination in animal tissues, to check the quality of measurements, and to validate the measurement method. Our method represented a high average percentage of recovery (> 95%) in the standard reference material matrix and a relative standard deviation (RSD) of 5% or less. Seasonality was determined to be a significant factor influencing the level of contamination of a given individual, both through mercury methylation within the aquatic environment and through fish ingestion by this apex semi-aquatic predator (guard hairs (p = 0.01); underfur (p = 0.04); kidney (p = 0.03); liver (p = 0.03)). Sex, location, and body size were not found to have a significant influence on heavy metal concentrations in river otters sampled in terms of season.

How harbour seals (Phoca vitulina) encode goals relative to landmarks.

Visual landmarks are defined as objects with prominent shape or size that distinguish themselves from the background. With the help of landmarks, animals can orient themselves in their natural environment. Yet, the way in which landmarks are perceived and encoded has previously only been described in insects, fish, birds, reptiles and terrestrial mammals. The present study aimed to provide insight into how a marine mammal, the harbour seal, encodes goals relative to landmarks. In our expansion test, three harbour seals were trained to find a goal inside an array of landmarks. After diagonal, horizontal or vertical expansion of the landmark array, the search behaviour displayed by the animals was documented and analyzed regarding the underlying encoding strategy. The harbour seals mainly encoded directional vector information from landmarks and did neither search arbitrarily around a landmark nor used a rule-based approach. Depending on the number of landmarks available within the array, the search behaviour of some harbor seals changed, indicating flexibility in landmark-based search. Our results present the first insight into how a semi-aquatic predator could encode landmark information when swimming along the coastline in search of a goal location.

Dendropsophus minutus (Hylidae) tadpole evaluation of predation risk by fishing spiders (Thaumasia sp.: Pisauridae) is modulated by size and social environment

Predator–prey interactions can cross ecosystem boundaries and the outcome of these interactions is seen in prey defensive behavior. We aimed to test how the presence of a semi-aquatic predator alters the behavior and foraging microhabitat of Dendropsophus minutus tadpoles when they are either in groups or alone. We hypothesized that in the presence of a predator, Thaumasia fishing spider, tadpoles will be (1) less active; (2) forage far from the predator and; (3) forage evenly when in groups. We measured activity and foraging microhabitat as the proportion of time spent moving, and the total percentage of food removed from the upper and lower inner surfaces of the aquarium, respectively. The presence of the spider reduced tadpole activity by 24% compared to treatments without predators. Contrary to our expectations, solitary tadpoles were 34% more active than tadpoles in groups, and larger larvae were less active than smaller ones. The presence of the fishing spider decreased tadpoles activity, but the presence of conspecifics did not dilute the predator effect. Larger larvae are under more substantial selective pressure than smaller ones. Finally, our experiment empirically demonstrates that predator effects are transferable, generating a cascading system, and affecting the recipient ecosystem in various manners.

Comparing DNA metabarcoding with faecal analysis for diet determination of the Eurasian otter (Lutra lutra) in Vejlerne, Denmark

The Eurasian otter (Lutra lutra) is a semi-aquatic predator that lives in a wide range of aquatic habitats. Knowledge of the diet of predators is essential for the management and conservation of the species and their habitats. We assessed the diet of otters in fifty-three faecal samples (spraints) by morphological analysis of undigested prey remains and by DNA metabarcoding approaches with two different blocking primers. The blocking primers were shown to be similarly effective in repressing host DNA, improving amplification of non-host taxa. The analyses were conducted to compare the accuracy of the two methods. The prey items were categorized to the highest possible taxonomic resolution, and relative frequency of occurrence was applied in order to compare the morphological and DNA results. The bulk score for difference prey items in the spraints was based on volume estimates in macroscopic observations. The two methods had an overlap of identified prey species ranging from 69.9 to 72.9% (depending on the kind of primers) meaning that a large portion of prey items found by one method was replaced by other prey items in the other method and that most prey items found through DNA-metabarcoding are considered new when compared with the morphological analysis. Therefore, applying both morphological and DNA analysis is crucial in order to determine the diet of otters and, possibly, other predatory species.

The youngest occurrence of embolomeres (Tetrapoda: Anthracosauria) from the Sunjiagou Formation (Lopingian, Permian) of North China

Abstract. Embolomeri were semiaquatic predators prevalent in the Carboniferous, with only two species from the early Permian (Cisuralian). A new embolomere, Seroherpeton yangquanensis gen. et sp. nov. (Zoobank Registration number: urn:lsid:zoobank.org:act:790BEB94-C2CC-4EA4-BE96-2A1BC4AED748, registration: 23 November 2020), is named based on a partial right upper jaw and palate from the Sunjiagou Formation of Yangquan, Shanxi, China, and is late Wuchiapingian (late Permian) in age. It is the youngest embolomere known to date and the only embolomere reported from North China Block. Its phylogenetic position within Embolomeri is confirmed by the strongly developed descending flange on the quadrate ramus of the pterygoid. The new taxon is unique among embolomeres by features like a partial coverage of a denticle shagreens on the pterygoid; presence of a cylindrical shaft on the pterygoid, and two pairs of very large ectopterygoid tusks. Phylogenetic analysis shows Seroherpeton as being the sister group of a clade consisting of Proterogyrinus, Archeria, and Pholiderpeton. We hypothesize that the dispersal and decline of the embolomeres from Carboniferous to late Permian (Lopingian) is related to the climate changes, especially aridification, of the paleotropical regions.

A systematic review of the giant alligatoroid Deinosuchus from the Campanian of North America and its implications for the relationships at the root of Crocodylia

ABSTRACT Deinosuchus is a lineage of giant (≥10 m) Late Cretaceous crocodylians from North America. These were the largest semiaquatic predators in their environments and are known to have fed on large vertebrates, including contemporaneous terrestrial vertebrates such as dinosaurs. Fossils have been found in units of Campanian age from northern Mexico to Montana in the west and Mississippi to New Jersey in the east. Three species have been named, and recent consensus suggests that they represent a single, widely ranging species. The authors studied newly collected material from western Texas and increased sampling from throughout North America to review species-level systematics of Deinosuchus and help refine its phylogenetic placement among crocodylians. Deinosuchus from eastern and western North America can be consistently differentiated and represent different species. A phylogenetic study is conducted including new character states. This work reinforces the identity of the ‘terror crocodile’ as an alligatoroid. Reference to the holotypes indicates that the generic name holder, Deinosuchus hatcheri, is extremely incomplete. As a result, the three known species of Deinosuchus cannot be differentiated. To ensure nomenclatural stability, the type species for Deinosuchus should be transferred to Deinosuchus riograndensis, a species known from multiple mostly complete individuals. Additionally, Deinosuchus rugosus is based on a holotype that is not diagnostic, and a new species, Deinosuchus schwimmeri, is named to encompass some specimens formerly assigned to D. rugosus.

Predation on Amphibians May Enhance Eurasian Otter Recovery in Southern Italy.

Mediterranean freshwaters undergo extreme seasonal variation in water flow, which, exacerbated by water withdrawal for agriculture or hydroelectric purposes, may affect fish communities and thus prey availability for semi-aquatic predators, such as Eurasian otter Lutra lutra. To investigate the role played by food availability on the ongoing recovery of an otter population at the southernmost limit of its Italian range, we assessed otter diet by the analysis of 357 spraints collected from 2014 to 2017 on eight rivers, and both fish and amphibian availability by, respectively, electrofishing and visual encounter surveys. Fish and amphibians formed the bulk of otter diet, the latter resource contributing as much as fish to otter diet in spring. Use by otters of both fish and amphibians depended only fish availability, suggesting that amphibians constituted an alternative resource to be exploited in conditions of fish shortage. Accordingly, electrofishing showed that fish biomass may barely be sufficient to sustain the current otter population. ATR-FT-IR spectroscopy allowed to point out for the first time the occurrence of amphibian eggs in otter spraints, although the co-occurrence of anuran bones did not allow to discriminate between direct and passive predation. Overall results indicate that the expansion or even survival of this small otter population may depend on the effective management of water resources and reinforcement of fish assemblages.

Limited Animal-Facilitated Nutrient Transfer across an Aquatic–Terrestrial Interface in a Southern African Savanna

Animal-mediated nutrient transfer facilitates nutrient cycling in marine, freshwater and terrestrial ecosystems via the deposition of aquatically-derived nutrients such as nitrogen (N) and carbon (C). This mode of nutrient transfer has not been studied in southern African river systems. We investigated nutrient deposition associated with defecation, urination, and scent-marking at latrine sites of a semi-aquatic predator species (African clawless otters Aonyx capensis) in a riparian zone of a Bankenveld savanna ecosystem. We provide a comparison of stable nitrogen isotopes (δ15N) measured in soil, vegetation and faecal material, between latrine and paired control sites. Latrine sites displayed higher δ15N values than the paired non-latrine sites, but only at the area of direct deposition (soil surfaces). This effect dissipated as the distance from direct contact increased, while no significant difference in δ15N values was detected for sub-surface soil samples. Plants displayed varying trends of enriched δ15N values between the latrine and paired control sites. These results suggest that several factors and processes such as leaching, mineralization, ammonia volatilization, and nitrogen acquisition influence the nutrient availability within latrine-soil-vegetation systems in riparian zones of African savanna ecosystems.

Think of what lies below, not only of what is visible above, or: a comprehensive zoological study of invertebrate communities of spring habitats

Springs are interface habitats between the surface and subterranean environments, often neglected by zoological studies and generally regarded only from a surface perspective. Springs are also often collected and managed by humans: catching buildings that collect spring water may provide an accessible window over groundwaters. With this paper, we aim to assess the determinants of invertebrates’ occurrence in springs using a comprehensive approach and considering the role of catching buildings and of predator occurrence. During 2017 and 2018, we performed six repeated surveys in 44 springs of N-Italy. We distinguished between collected and natural springs, assessed the springs morphological features and recorded the occurrence of predator Salamandra salamandra (Linnaeus, 1758) larvae and of four invertebrate taxa corresponding to strictly spring-dwelling, groundwater-dwelling and stream-dwelling groups, such as the gastropod Graziana alpestris (Frauenfeld, 1863), the amphipods Niphargus thuringius Schellenberg, 1934 and Gammarus balcanicus Schäferna, 1922 and dipterans larvae of the family Tipulidae. We used a constrained redundancy analysis to evaluate the relative role of fire salamander occurrence and of springs features on the occurrence of the invertebrate taxa surveyed. Spring typology and fire salamander larvae were the major determinants of spring invertebrates’ occurrence. G. alpestris was positively related to artificial catching structures. Fire salamander was related to the occurrence of N. thuringius, G. balcanicus and Tipulidae larvae. Our results provide evidence that catching spring structures can significantly favour the detection of strictly spring-dwelling species; moreover, we reveal that the breeding of semi-aquatic predators like salamanders may play important roles on the community of invertebrates occurring in the spring habitats.

A large neosuchian crocodyliform from the Upper Cretaceous (Cenomanian) Woodbine Formation of North Texas

ABSTRACTA new taxon of neosuchian crocodyliform, Deltasuchus motherali, gen. et sp. nov., is described on the basis of a partial skull recovered from the Arlington Archosaur Site within the Upper Cretaceous (Cenomanian) Woodbine Formation of north-central Texas. This productive locality represents a delta plain ecosystem preserving a diverse coastal fauna, including lungfish, turtles, dinosaurs (ornithopods and theropods), and crocodyliforms. Prior to this discovery, the only identified crocodyliforms from the Woodbine Formation had been the longirostrine taxa Terminonaris and Woodbinesuchus. This new taxon is differentiated from other known crocodyliforms by the presence of dual pseudocanines on both the dentary and maxilla; anterior and posterior rami of jugal comparable in depth; anterolaterally facing margin on the dorsal portion of the postorbital; contact between the descending process of the postorbital and the ectopterygoid; and a large, deep fossa on the ventral surface of the quadrate. Phylogenetic analysis recovers D. motherali as the sister taxon to Paluxysuchus newmani from the Lower Cretaceous Twin Mountains Formation of Texas. This clade lies within Neosuchia basal to Goniopholididae + Eusuchia. The associated cranial elements of this new crocodyliform represent a large, broad-snouted individual, an ecomorphotype often associated with the semiaquatic ambush predator niche in this clade, and one not previously reported from the formation.

The concept of behavioural needs in contemporary fur science: do we know what American mink (Mustela vison) really need?

AbstractThis paper discusses the ethical implications of applying the concept of behavioural needs to captive animals. This is done on the basis of analysing the scientific literature on farmed mink and their possible need for swimming. In the wild, American mink (Mustela vison) are semi-aquatic predators, lending initial support to the claim that captive mink with no access to adequate swimming facilities experience a thwarted behavioural need. Scientific studies show a disparate picture. Consumer-demand experiments, where the animals have been conditioned to work for environmental resources, consistently show that mink place high value on swimming water, whereas other studies indicate the opposite, which has led scientists to question whether this preference constitutes a genuine behavioural need. In this paper, we take a methodological turn and discuss whether the oft-used concept of behavioural needs provides the best possible account of what is indispensable to an animal. Seen from a more complex understanding of behavioural needs, we suggest that lack of swimming opportunities for farmed mink constitutes a welfare problem. Further, it is argued that the decision of which paradigm to use in research on animal needs has not only ethical consequences, but is in itself a value-based choice.

A new otter of giant size, Siamogale melilutra sp. nov. (Lutrinae: Mustelidae: Carnivora), from the latest Miocene Shuitangba site in north-eastern Yunnan, south-western China, and a total-evidence phylogeny of lutrines

Otters (subfamily Lutrinae) are semi-aquatic predators in the family Mustelidae. Modern otters have a worldwide distribution but their fossil record is poor, often consisting of fragmentary jaws and teeth. Multiple lineages have developed bunodont dentitions with enlargements of molars, usually for cracking molluscs or other hard foods. Some lineages have evolved badger-like teeth and, as a result, were often confused with melines (Old World badger clade). Siamogale thailandica Ginsburg, Invagat, & Tassy, 1983 from the middle Miocene basin of Mae Moh in northern Thailand is one such species, whose fragmentary dental remains have thus far impeded our understanding. A new species of fossil otter, Siamogale melilutra sp. nov., represented by a nearly complete cranium, mandible and partial skeletons of at least three individuals, was recovered from the latest Miocene (∼6.2 Ma) lignite beds of the Shuitangba Site in north-eastern Yunnan Province, south-western China. Computed tomography (CT) restoration of the crushed skull reveals a combination of otter-like and badger-like cranial and dental characteristics. The new species belongs to the Lutrinae because of its possession of a large infraorbital canal and ventral expansion of the mastoid process, among other traits. A distally expanded M1, however, gives a badger-like appearance. In overall morphology the Shuitangba otter is closest to Siamogale thailandica. A previously described jaw (‘Lutra’ aonychoides) from the early Pliocene of the Yushe Basin in north China is also here referred to S. melilutra. No previous attempt has been made to provide a global phylogenetic framework for otters. We present the first combined morphological and molecular (nuclear and mitochondrial DNAs) character matrices of five extant (Pteronura, Lontra, Enhydra, Aonyx, Lutra) and eight extinct genera (Tyrrhenolutra, Paralutra, Paludolutra, Enhydritherium, Siamogale, Vishnuonyx, Sivaonyx, Enhydriodon) to better understand the evolution of bunodont otters. Parsimony and Bayesian analyses consistently recover an eastern Asian clade that includes forms from Shuitangba, Yushe and Mae Moh, all of which are referred to Siamogale.http://zoobank.org/urn:lsid:zoobank.org:pub:5C637018-0772-4C78-AA4B-783B71085D9D

Biogeographic patterns in the feeding habits of the opportunist and semiaquatic Neotropical otter

We evaluated the biogeographic factors that influence composition and diversity of the Neotropical otter diet. We also tested whether Lontra longicaudis selected fish in its diet per their availability. We collected data from 41 studies, covering most of the otter’s distribution, 32 of which had prey identified to family level. Fish was the main prey for L. longicaudis throughout the species range. However, its frequency was higher in sites farther from the coast and at higher slopes. Alternative prey items compensate the decrease in fish. Temperature seasonality, slope, and distance to coast were the most important factors determining the diversity of the otter’s diet. Populations in areas with more variation in temperature and/or closer to the coast showed a more diverse diet with an increase of alternative prey. Trophic diversity was positively correlated with temperature seasonality but negatively correlated with the slope and distance to coast. As an opportunist, semiaquatic predator with a wide distribution range, L. longicaudis has a flexible diet, and this plasticity might be explained by the wide range of habitats occupied by otters. Furthermore, Neotropical otter diet was also found to be more similar in geographically closer areas, as well as in similar environment types.

Factors driving semi-aquatic predator occurrence in traditional cattle drinking pools: conservation issues

<p>In several cases, human impact on water bodies and on their freshwater communities is detrimental, but in some cases the human activity may favour and enhance the biodiversity of small water bodies, as traditional cattle drinking pools. Despite their small size, small water bodies may constitute hot spot of biodiversity often representing the only lentic aquatic biotope in landscapes where superficial water lacks or flows in lotic environments like creeks and streams. Predators are good indicators of biodiversity in ponds and give information of food chain web complexity. In particular, semi-aquatic predators like amphibians and dragonflies may account for a substantial percentage of energy flow between aquatic and terrestrial ecosystems. In this study, we evaluated the conservation value of traditional cattle drinking pools building by assessing the factors determining the occurrence and distribution of the semi-aquatic predators. From April to August 2015, we investigated 30 distinct pools recording several abiotic and biotic environmental variables. We detected 4 semi-aquatic predators: <em>Salamandra salamandra</em> larvae, <em>Triturus carnifex</em>, <em>Aeshna</em> sp. larvae and <em>Libellula</em> sp. larvae. Abiotic features played a major role in shaping the predator community that resulted linked to stable, with no dryness period, and large drinking pools. Invertebrate prey biomass was not particularly important, while vegetation cover and occurrence of unpalatable tadpoles were the most important biotic features of the pools. Our study provides novel evidence on the importance of cattle drinking pools management to preserve biodiversity especially in areas where traditional pastoral activity is disappearing.</p>

Early crocodylomorph increases top tier predator diversity during rise of dinosaurs.

Triassic predatory guild evolution reflects a period of ecological flux spurred by the catastrophic end-Permian mass extinction and terminating with the global ecological dominance of dinosaurs in the early Jurassic. In responding to this dynamic ecospace, terrestrial predator diversity attained new levels, prompting unique trophic webs with a seeming overabundance of carnivorous taxa and the evolution of entirely new predatory clades. Key among these was Crocodylomorpha, the largest living reptiles and only one of two archosaurian lineages that survive to the present day. In contrast to their existing role as top, semi-aquatic predators, the earliest crocodylomorphs were generally small-bodied, terrestrial faunivores, occupying subsidiary (meso) predator roles. Here we describe Carnufex carolinensis a new, unexpectedly large-bodied taxon with a slender and ornamented skull from the Carnian Pekin Formation (~231 Ma), representing one of the oldest and earliest diverging crocodylomorphs described to date. Carnufex bridges a problematic gap in the early evolution of pseudosuchians by spanning key transitions in bauplan evolution and body mass near the origin of Crocodylomorpha. With a skull length of >50 cm, the new taxon documents a rare instance of crocodylomorphs ascending to top-tier predator guilds in the equatorial regions of Pangea prior to the dominance of dinosaurs.

Humeral morphology of the early Eocene mekosuchine crocodylian Kambara from the Tingamarra Local Fauna southeastern Queensland, Australia

Stein, M., Salisbury, S.W., Hand, S.J., Archer, M. & Godthelp, H., December 2012. Humeral morphology of the early Eocene mekosuchine crocodylian Kambara from the Tingamarra Local Fauna southeastern Queensland, Australia. Alcheringa 36, 473–486. ISSN 0311-5518. Mekosuchines (Crocodylia; Crocodyloidea) were a clade of crocodylians endemic to Australia and the South Pacific that underwent radiation during the Cenozoic. Numerous questions about mekosuchine palaeoecology remain unanswered. Tantalizing among these is the possibility that some mekosuchines were primarily terrestrial. To date, studies of mekosuchines have focused mainly on the cranium. However, the morphological signal for terrestriality is more likely to be found in the postcranial skeleton. Here, we present a comparative morphological study of fossil humeri referable to Kambara from the early Eocene Tingamara Local Fauna, Murgon, southeastern Queensland. The humeri of Kambara do not show the torsion between the proximal and distal extremity seen in extant crocodylians, illustrated here with Crocodylus porosus and Crocodylus johnstoni. They also differ in the structure of the medial and lateral condyles of the distal extremity. When the effects of these features on musculature and articulation are considered, it appears that the forelimb of Kambara could have facilitated a greater force at the glenohumeral joint and possibly swung the lower forelimb faster with a greater arc of motion than Australia's extant crocodylians. This is conducive to an improved capacity for both terrestrial locomotion and paraxial swimming. Although the former case suggests that Kambara may not have been as closely tied to water as extant crocodylians, it is unusual given the typically broad rostra of the cranium. Among crocodylians this is a common characteristic of semi-aquatic ambush predators. This study shows the utility of the postcranial skeleton in interpreting crocodylian palaeoecology. Michael Stein [michael.stein@student.unsw.edu.au] (corresponding author), Suzanne J. Hand [s.hand@unsw.edu.au], Michael Archer [m.archer@unsw.edu.au] and Henk Godthelp [h.godthelp@unsw.edu.au], School of Earth and Environmental Science, University of New South Wales, Sydney, NSW, 2052, Australia; and Steven W. Salisbury [s.salisbury@uq.edu.au], School of Biological Sciences, University of Queensland, Brisbane, Qld, 4072, Australia. Received 13.1.2012, revised 24.2.2012, accepted 28.2.2012.