Place recognition using batlike sonar

Echolocating bats have excellent spatial memory and are able to navigate to salient locations using bio-sonar. Navigating and route-following require animals to recognize places. Currently, it is mostly unknown how bats recognize places using echolocation. In this paper, we propose template based place recognition might underlie sonar-based navigation in bats. Under this hypothesis, bats recognize places by remembering their echo signature - rather than their 3D layout. Using a large body of ensonification data collected in three different habitats, we test the viability of this hypothesis assessing two critical properties of the proposed echo signatures: (1) they can be uniquely classified and (2) they vary continuously across space. Based on the results presented, we conclude that the proposed echo signatures satisfy both criteria. We discuss how these two properties of the echo signatures can support navigation and building a cognitive map. DOI: http://dx.doi.org/10.7554/eLife.14188.00

Coordination of bat sonar activity and flight for the exploration of three-dimensional objects

SUMMARY The unique combination of flight and echolocation has opened the nocturnal air space as a rich ecological niche for bats. By analysing echoes of their sonar emissions, bats discriminate and recognize three-dimensional (3-D) objects. However, in contrast to vision, the 3-D information that can be gained by ensonifying an object from only one observation angle is sparse. To date, it is unclear how bats synchronize echolocation and flight activity to explore the 3-D shape of ensonified objects. We have devised an experimental design that allows creating 3-D virtual echo-acoustic objects by generating in real-time echoes from the bat's emissions that depend on the bat's position relative to the virtual object. Bats were trained to evaluate these 3-D virtual objects differing in their azimuthal variation of either echo amplitude or spectral composition. The data show that through a very effective coordination of sonar and flight activity, bats analyse an azimuthal variation of echo amplitude with a resolution of approximately 16 dB and a variation of echo centre frequency of approximately 19%. Control experiments show that the bats can detect not only these variations but also perturbations in the spatial arrangement of these variations. The current experimental paradigm shows that echolocating bats assemble echo-acoustic object information – acquired sequentially in flight – to reconstruct the 3-D shape of the ensonified object. Unlike previous approaches, the recruitment of virtual objects allows for a direct quantification of this reconstruction success in a highly controlled experimental approach.</jats:p

Phillipsite altered to analcime in basal Windsor [shallow-water marine] carbonates of Mississippian age in Nova Scotia

Phillipsite crystals altered to analcime are reported for the first time in ancient shallow-water marine carbonates (Lower Windsor Group, Cape Breton Island, Nova Scotia, Canada). </jats:p

Conodont biostratigraphy of the Codroy Group (Lower Carboniferous), southwestern Newfoundland, Canada

Four stratigraphically successive conodont assemblage zones have been recognized in the Lower Carboniferous Codroy Group of southwestern Newfoundland. The Diplognathodus Zone is confined to the basal Ship Cove Limestone, and to a highly fossiliferous correlative at Aguathuna. The overlying Taphrognathus Zone occurs in carbonates in the stratigraphic interval above the sequence of massive sulphates and thick clastics. The Taphrognathus Zone, as well as the successive Cavusgnathus Zone, has been recognized on Fischells Brook, as well as in the complex section south of Codroy. The highest conodont zone, the Gnathodus Zone, has been recognized in the Crabbes–Jeffreys Limestone of the St. George's Bay area, and from south of Codroy.The discovery of conodonts of the Diplognathodus Zone in marine strata that are stratigraphie and lithologie correlatives of the Macumber and the Gays River Formations of Nova Scotia now makes it possible to microfaunally characterize the A Subzone, a macrofaunal subzone established in the Windsor Group of Nova Scotia.The Taphrognathus and Cavusgnathus Zones of the Codroy Group of Newfoundland correlate with the lower and upper B Subzone of the Lower Windsor Group of Nova Scotia, respectively. The Gnathodus Zone correlates with the C, D, and E Subzones of the Upper Windsor Group of Nova Scotia. </jats:p