The
Joaquinraptor holotype likely belonged to an animal that was more than long. Based on the circumference of the femur (), a body mass of could be calculated. Its closest relatives within the Megaraptoridae—
Aerosteon,
Maip,
Megaraptor, and
Tratayenia—all reached or exceeded this size. In particular,
Maip has been estimated at around , making it the largest known member of the clade. Earlier-diverging and older Australian specimens, including
Australovenator, were smaller, at around long and in weight. Based on the absence of observable sutures (which are an indicator of immaturity), the
Joaquinraptor holotype can be identified as belonging to a sexually mature individual. However, the absence of an external fundamental system (EFS) in the
bone cortex when it died implies this animal had not yet reached somatic maturity when it died. At least 19 lines of arrested growth (LAGs) were observed using an osteo
histological sample of the tibia in cross-section. If these layers were deposited annually, the holotype individual would have been at least 19 years old.
Paleobiology The right humerus of a
crocodyliform was found in direct association with the dentaries of
Joaquinraptor, contacting several tooth crowns and possibly bearing tooth marks. This may represent direct evidence of prey selection of
Joaquinraptor. Alternatively, this could represent evidence of
interspecific combat or competition. A third possibility, claimed to be less likely by Ibiricu and colleagues, is that the deposition of the humerus near the
Joaquinraptor holotype was coincidental, carried by water currents after the
Joaquinraptor had already died. However, this would imply a fairly high-energy environment capable of transporting other bones from the area, which is at odds with the discovery of the
Joaquinraptor material in partial articulation, meaning it was more likely deposited in an area of low water flow. == Classification ==