Pterodaustro guinazui (Bonaparte 1969, 1970, PVL 3860) Albian, Late Cretaceous, ~105 mya, ~3 m wingspan, ~30 cm skull length, was derived from a sister to Ctenochasma gracile and was the last and most derived in the ctenochasmatid lineage.

Larger overal and distinct from Cteochasma gracile, the skull of Pterodaustro had an upcurved rostrum. The upper teeth were short cones. The lower teeth were extremely long, flexible and oriented dorsally. The pterygoids were subequal to the ectopalatines.

The cervicals were slightly shorter. The torso was deeper. The sacrals were longer. The caudals were surprisingy long and robust. Comparisons to the embryo (below) indicate growth of the tail during maturity.

The scapula was smaller, the entire wing was more robust.

The pelvis was larger. The prepubis was indented ventrally. The hind limbs were more robust. The feet were relatively larger with metatarsals more subequal.

A growth series is known in Pterodaustro. We know of Pterodaustro embryo (Chiappe et al. 2004, see below), hatchlings (Codorniú and Chiappe 2004), juveniles, sexually mature specimens and larger, older adults (Chinsamy, Codorniú and Chiappe 2008, see below). These contradict earlier traditions (Wellnhofer 1970, Bennett 1993a, b, 1995, 1996a, 2001a,b, 2006, 2007, Wang and Zhou 2004) that pterosaurs matured allometrically, like birds, crocs and mammals. Rather they matured isometrically like Huehuecuetzpalli (Reynoso 1998). Other examples of pterosaur embryos include the IVPP specimen and the JZMP specimen. Note that the Pterodaustro embryo has adult proportions in the skull and elsewhere. The jaws were more curved, the teeth were shorter, the sternal complex was larger, the humerus was larger, the pelvis and prepubis were smaller, toe fivewais longer and the wing was slightly shorter. These characters would otherwise be considered traits to distinguish a species.

See more ctenochasmatids here. The dorygnathid tree is here. The pterosaur family tree is here.

The referred specimen of Eosipterus (D2514, Lü et al. 2006 ) nests with Pterodaustro. It has no skull. And the sternal complex is very large. Dalian Natural History Museum, Dalian, Liaoning, China.

Allkaruen koi (MPEF-PV 3613, Codorniú et al. 2016; Middle Jurassic) Represented by just a few skull bones and cervicals, this early relative of Pterodaustro was originally considered basal to wukongopterids and the invalid 'Pterodactyloidea.' The anterior mandibles curved upward and had large alveoli for long teeth. At mid mandible the alveoli became a long groove for the reception of thinner filter-feeding teeth. The skull was relatively small and comparable in size to that of an adult Pterodaustro.

Bonaparte J F 1970. Pterodaustro guinazui gen. et sp. nov. Pterosaurio de la Formacion Lagarcito, Provincia de San Luis, Argentina y su significado en la geologia regional (Pterodactylidae)", Acta Geologica Lilloana, 10: 209-225.

Chinsamy A, Codorniú L and Chiappe LM 2008. Developmental growth patterns of the filter-feeder pterosaur, Pterodaustro guinazui. Biology Letters, 4: 282-285.

Chiappe LM, Codorniú L, Grellet-Tinner G and Rivarola D. 2004. Argentinian unhatched pterosaur fossil. Nature, 432: 571.

Codorniú L and Chiappe LM 2004. Early juvenile pterosaurs (Pterodactyloidea: Pterodaustro guinazui) from the Lower Cretaceous of central Argentina. Canadian Journal of Earth Science 41, 9–18. (doi:10.1139/e03-080)

Codorniú L, Paulina-Carabajal A and Gianechini FA 2015. Braincase anatomy of Pterodaustro guinazui, pterodactyloid pterosaur from the Lower Cretaceous of Argentina. Journal of Vertebrate Paleontology, DOI:10.1080/02724634.2015.1031340

Codorniú L, Carabajal AP, Pol D, Unwin D and Rauhut OWM 2016. A Jurassic pterosaur from Patagonia. and the origin of the pterodactyloid neurocranium. PeerJ 4:e2311; DOI 10.7717/peerj.2311

Deeming C and Unwin DM 2007. Eggshell structure and its implications for pterosaur reproductive biology and physiology. Flugsaurier, the Wellnhofer pterosaur meeting, Munich, 12.

Grellet-Tinner G, Wroe S, Thompson SB and Ji Q 2007. A note on pterosaur nesting behavior. Historical Biology 19:273–277.

Ji Q, Ji S-A, Cheng Y-N, You HL, Lü J-C, Liu Y-Q and Yuan CX 2004. Pterosaur egg with leathery shell. Nature 432:572.

Lü J-C, Gao C-L, Meng Q-J, Liu J-Y, Ji Q 2006. On the Systematic Position of Eosipterus yangi Ji et Ji, 1997 among Pterodactyloids. Acta Geologicia Sinica 80(5):643-646.

wiki/Pterodaustro