L. robustus most likely had a slender body characteristic of extant members of
Leptoptilos, but was much larger in body size and height, with individuals reaching up to at least tall and weighing approximately .
Skeletal anatomy A fragment of a proximal left
carpometacarpus was one of the bones discovered to be a part of
robustus, consisting of half of the os metacarpale majus and the trochlea carpalis. Ventrally within the fossa infratrochlearis lies a 2-millimeter diameter pneumatic foramen, a feature that is characteristic of the genus
Leptoptilos. The morphology of the trochlea carpalis was also similar when compared to those of extant Leptoptilini members. Measurements of the proximal width and depth of the carpometacarpi fell within the range of the extant species
L. dubius, suggesting that
L. robustus was closer to
L. dubius' size based on carpometacarpal measurements alone. A fragmented distal left
ulna was found consisting of the distal articulation and a small part of the shaft. A distinct foramen is observable between the tuberculum carpale and the condylus ventralis ulnae. This foramen is present in extant
Leptoptilos species. When comparing the minimum width and minimum depth of the
robustus ulna to other extant
Leptoptilos members, the values fell within the upper size range of
L. dubius suggesting similar body length. Two femurs were found on the left and right sides. The left
femur was found nearly complete, broken in two and missing only the caput femoris. Evidence for large muscle attachment can be observed as a depression along the entire width of the femur. The shape of the femur is similar in morphology to the extinct species
L. falconeri, but agrees more closely in length with
L. dubius. However, comparing the minimum width and minimum depth of the shaft, the femur discovered falls within the range of
L. dubius. The
tibiotarsus was found fragmented into three parts consisting of the shaft and distal end. The distal condyles were absent. The bone wall is thicker than the largest species of extant and extinct
Leptoptilos. The size and shape of the sulcus extensorius discovered are very similar to
L. dubius than to other extinct
Leptoptilos species. The measurements of the tibiotarsus contrast with those of the carpometacarpus, ulna, and femur as being distinctly larger than other Leptoptilini species. The tibiotarsus lies very far outside the range of
L. dubius and is more similar in size to
L. siwalicensis. The right and left proximal scapulae are large with a distinct tuberculum coracoideum proximal to it. Both of the scapulae are larger than that of
L. crumeniferus, but fall within the size range of
L. dubius.
Diet of
L. robustus individuals next to a
Stegodon florensis carcass with a
Komodo dragon and
Trigonoceps vultures Large extant species of stork are typically scavengers of carrion and compete with carnivorous mammals. Pleistocene
Liang Bua was highly endemic and there were no or very few large carnivorous mammals that
L. robustus competed with for carrion. In the absence of such competition, food was more abundant. This abundance of food reduced the need to travel large distances in search of resources and would have put very little selection pressure on flight apparatuses and mechanisms.
L. robustus was likely heavily dependent on
carrion obtained from carcasses of the
dwarfed elephant-relative
Stegodon florensis, the only large herbivore native to the island for a large part of its diet, and likely heavily competed with other carnivores present on the island such as the
Komodo dragon and
Trigonoceps vultures for
Stegodon carcasses.. It probably also hunted giant rats and young Komodo dragons. Some speculate that these large storks may have fed upon a species of hominid,
Homo floresiensis, that coexisted with them during the Late Pleistocene. Commonly known as "hobbits," these small hominids reached an estimated in height, approximately half as tall as
L. robustus; adults and juveniles may have been prey for the giant stork. ==Discovery==