Later, when more remains were found, it was realized they could have been a separate species. This possible second species from Texas was provisionally referred to as a Quetzalcoatlus sp. by Alexander Kellner and Langston in 1996, indicating that its status was too uncertain to give it a full new species name. The smaller specimens are more complete than the Q. northropi holotype, and include four partial skulls, though they are much less massive, with an estimated wingspan of 5.5 meters (18 ft). Quetzalcoatlus northropi is the largest known animal to have ever been able to fly. When it was first discovered, scientists estimated that the fossil came from a pterosaur with a wingspan of up to 45 feet (13.7m), choosing the middle between three extrapolations from the proportions of other pterosaurs that gave an estimate of 40, 50 and 70 feet respectively. in 1981, futher study showed that this estimate was too large, and lowered the estimated wingspan to 50 feet (15m). More recently, the wingspan estimated has been reduced yet again, this time to 36 feet
Later, when more remains were found, it was realized they could have been a separate species. This possible second species from Texas was provisionally referred to as a Quetzalcoatlus sp. by Alexander Kellner and Langston in 1996, indicating that its status was too uncertain to give it a full new species name. The smaller specimens are more complete than the Q. northropi holotype, and include four partial skulls, though they are much less massive, with an estimated wingspan of 5.5 meters (18 ft). Quetzalcoatlus northropi is the largest known animal to have ever been able to fly. When it was first discovered, scientists estimated that the fossil came from a pterosaur with a wingspan of up to 45 feet (13.7m), choosing the middle between three extrapolations from the proportions of other pterosaurs that gave an estimate of 40, 50 and 70 feet respectively. in 1981, futher study showed that this estimate was too large, and lowered the estimated wingspan to 50 feet (15m). More recently, the wingspan estimated has been reduced yet again, this time to 36 feet