The fossil, discovered in 2010 in sediment among the cliffs above La Estafeta beach, contains the complete palate, complete trachea, skull, voice box, and eye bones. The fossil shows L. scagliai was a medium-sized phorusrhacid around four feet tall and lived in Argentina approximately 3.5 million years ago during the Pliocene Epoch.
L. scagliai likely roamed in grassland and weighed around 40 pounds (18 kg). The joints separating the skulls bones were fused, unlike modern birds, and that may have helped it batter prey. CT scans of its inner ear show that it could only hear frequencies between about 380 and 4230 hertz, and probably had a deep voice to match.
The below cladogram is simplified after the analysis of Derange et al. (2015).