Abstract:This study is based on the analysis of burrow casts of three species of armadillos from central Argentina: Chaetophractus villosus, Chaetophractus vellerosus, and Zaedyus pichiy (Chlamyphoridae: Euphractinae). The aim of this work was to identify key ichnologic signatures of Euphractinae armadillo burrows for application to the paleoecological and behavioral interpretation of fossil examples. A total of 15 active burrows from different biogeographic provinces were casted with polyurethane foam and then excavat… Show more
“…Presence of a bilobed bottom is a feature typical of some fossil and extant tetrapod burrows 21 – 27 . This feature was interpreted as reflecting protracted occupation of a burrow and repeated passage of the occupant, thus producing a differential compaction of the sides of burrow bottom 27 , 28 . Figure 5 Surface ornamentation of R .…”
Scarce fossil tetrapod burrows have been recorded in Cretaceous rocks, which is probably linked to the dominant equable climates that existed for most of this period. The occurrence of Cretaceous tetrapod burrows from Patagonia (Chubut Province, Argentina) dated between 118 and 115 million years ago, gives insights into their paleoecology and paleoenvironment. The rocks containing the tetrapod burrows are of pyroclastic origin and represent eolian dunes and ash-fall deposits, some reworked by fluvial currents and others showing soil development. Fossil burrow casts preserved in a paleosol are composed by a ramp with a slightly curved or straight path in plan-view and lacking bifurcation, a rounded termination with no enlargement, showing a reniform cross-section, and are assigned to the ichnospecies Reniformichnus katikatii. The strongly flattened cross-sectional shape of the burrow casts and comparison with modern lizard burrows suggest that the producers were lepidosaurs (body mass = 50–323 g). Among Cretaceous fossorial lepidosaurs from Patagonia, the best candidate is an eilenodontine sphenodontian. Sphenodontians burrowed in the fossil soils where also arthropods, earthworms and shrubby plants thrived. The rare occurrence of tetrapod burrows in Cretaceous rocks is linked to stressing conditions related to frequent arrival of volcanic ash and a semiarid seasonal climate.
“…Presence of a bilobed bottom is a feature typical of some fossil and extant tetrapod burrows 21 – 27 . This feature was interpreted as reflecting protracted occupation of a burrow and repeated passage of the occupant, thus producing a differential compaction of the sides of burrow bottom 27 , 28 . Figure 5 Surface ornamentation of R .…”
Scarce fossil tetrapod burrows have been recorded in Cretaceous rocks, which is probably linked to the dominant equable climates that existed for most of this period. The occurrence of Cretaceous tetrapod burrows from Patagonia (Chubut Province, Argentina) dated between 118 and 115 million years ago, gives insights into their paleoecology and paleoenvironment. The rocks containing the tetrapod burrows are of pyroclastic origin and represent eolian dunes and ash-fall deposits, some reworked by fluvial currents and others showing soil development. Fossil burrow casts preserved in a paleosol are composed by a ramp with a slightly curved or straight path in plan-view and lacking bifurcation, a rounded termination with no enlargement, showing a reniform cross-section, and are assigned to the ichnospecies Reniformichnus katikatii. The strongly flattened cross-sectional shape of the burrow casts and comparison with modern lizard burrows suggest that the producers were lepidosaurs (body mass = 50–323 g). Among Cretaceous fossorial lepidosaurs from Patagonia, the best candidate is an eilenodontine sphenodontian. Sphenodontians burrowed in the fossil soils where also arthropods, earthworms and shrubby plants thrived. The rare occurrence of tetrapod burrows in Cretaceous rocks is linked to stressing conditions related to frequent arrival of volcanic ash and a semiarid seasonal climate.
“…Excavated dens, dwellings and warrens are widespread among extant fossorial and subterranean tetrapods, and involve complex burrow architectures and geometries that vary with the amount of time that the producers spend underground and the particular function of each element of the burrow (Kinlaw 1999). Fossorial animals (such as the caviid, chinchillid, octodontid and sciurid rodents, lagomorphs and most of the cingulates, among others) produce burrow systems that remained open all the time, to enable the constant transit of animals for above‐ground foraging and other activities (Nevo 1979; Kinlaw 1999; Cardonatto & Melchor 2021). In contrast, most of the burrows of fully subterranean tetrapods, such as those of the Ctenomys spp., have permanently plugged entrances (Melchor et al .…”
Section: Discussionmentioning
confidence: 99%
“…In this case, individuals prospect for food mainly underground. Open burrows are usually preserved with passive laminated, small‐scale cross‐bedding filling (Loope 2006; Cardonatto & Melchor 2021) or as cone tops (Loope 2008), just as occur in several burrows in the Buena Vista Formation (Table 2). Plugged burrows, in contrast, are mostly preserved with massive fillings related to the collapse of the roof (Loope 2006; Dentzien‐Dias & Figueiredo 2015; Cardonatto & Melchor 2021).…”
Section: Discussionmentioning
confidence: 99%
“…The description of the burrow architecture, surficial morphology and fills follows the definitions of Hasiotis et al . (2007), Bordy & Krummeck (2016) and Cardonatto & Melchor (2021). Data regarding the occurrence, architecture and filling of each burrow are given in Table 2.…”
We describe for the first time the presence of straight, curved and quasi‐helical burrows preserved in plan, oblique and transversal views in the aeolian strata of the Permo‐Triassic Buena Vista Formation (Paraná Basin), Rio Grande do Sul, southern Brazil. The morphology of the burrows is similar to that of others found in Guadalupian to Early Triassic‐aged deposits in several parts of the world. Of these, middle Permian dicynodont‐bearing helical burrows (Daimonelix) and Early–Middle Triassic kidney‐shaped burrows (Reniformichnus), both from the Karoo Basin of South Africa, show a remarkable similarity to the Brazilian burrows, prompting a discussion of the probable producers. Dicynodonts, cynodonts, therocephalian and/or procolophonians are among the probable producers of such burrows, based on size compatibility between the burrows and estimates of body size for the fossil taxa, along with the presence of skeletal adaptations in Permo‐Triassic tetrapods for digging (bone micro‐ and macrostructure). Last, we discuss some behavioural aspects of the producer of the burrows, mainly due to the presence of passive filling and bilobate bottoms in the tunnels, which indicates that they remained open as long as they were occupied. The burrows were excavated in a dry aeolian system that occurred in the Guadalupian–Induan interval of Brazil, representing the oldest unambiguous record of tetrapod dwelling structures in such an environment, and providing new and unprecedented information regarding the colonization of deserts by tetrapods during the end‐Permian biotic crisis.
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