Earlier we looked at the descendents of Scaphognathus that shrank through Ornithocephalus to begat Pterodactylus. Then, we followed another shrinkage through No. 6 that begat Germanodactylus. Two germanodactylids were basal to lineages that ultimately produced Tupuxuara and Pteranodon among others.
Start Small and Get Smaller
We begin this clade with a small Scaphognathus, the Maxberg specimen, No. 110 in the Wellnhofer (1975) catalog. It was originally considered a juvenile because it stood only as high as the hips of the holotype, No. 109 and it appeared to have the expected juvenile proportions. Actually it was a small adult as we learned earlier. Distinct from SMNS 59395 the skull of the Maxberg specimen had a relatively shorter, blunter skull and larger orbit. The teeth were more robust. The postorbital process of the jugal was vertical. The premaxillary teeth are not so reduced. The quadratojugal process of the jugal is reduced to a nub. The mandible appears to shallow posteriorly. The cervicals were shorter, half the torso length. The tail was shorter and more gracile. Extended hemal arches and zygopophyses are present, but extremely gracile. The sternal complex was more circular. The humerus was greatly reduced. The ulna and radius were shorter. Manual digits II and III were subequal. The wing was slightly shorter. The ischium was broader, higher and smaller. The small foot was just longer than half the tibia. Metatarsal I was longer than mt II. Pedal 5.1 extended nearly to the ungual of digit IV.
TM 13104 (Winkler 1870, No. 34 in the Wellnhoger 1970 catalog) was considered a juvenile Pterodactylus, but it is unrelated. Distinct from Scaphognathus, No. 110, the skull of No. 34 was shorter with a larger orbit. Following a shallow premaxilla, the naris was still separate from the antorbital fenestra The medial premaxillary teeth were oriented anteriorly. The rostral teeth were the same size and tiny. Extended hemal arches and zygopophyses were absent, but the caudals were more robust. The sternal complex shield was anteroposteriorly shorter with lateral processes enlarged. The scapula was subequal to the coracoid. The metacarpus was greatly elongated and subequal to the ulna. The proximal wing elements were longer such that the joint between m4.2 and m4.3 was beyond the elbow. The ischium was broad and its rims approach both the pubis and ilium. Metatarsal V was shorter. The metatarsals were not appressed.
Gmu-10157 (undescribed) was considered a juvenile Pterodactylus, but it is unrelated. Distinct from No. 34, the skull of Gmu-10157 had a longer skull and deeper premaxilla, as in Scaphognathus, No. 110. The antorbital fenestra was elongated anteriorly and the naris was greatlty reduced to the size of the secondary naris. The teeth were larger than in No. 34 and smaller than in No. 110. The postorbital was raised to the top of the orbit. The cervicals were elongated. The humerus was more elongated and robust. Fingers I-III were longer. The prepubis was broader. The ischium was smaller. The tibia was more robust. Pedal digit V was longer.
Relatively Gigantic Yixianopterus is Where Cycnorhamphids and Ornithocheirds Part Company
Yixianopterus jingangshanensis JZMP V-12 (Lü et al. 2006) ~20 cm skull length, Barremian/Aptian Early Cretaceous ~125 mya, was considered an ornithocheirid pterosaur like Haopterus, but it also nests at the base of the Cycnorhamphidae. Overall much larger than and distinct from Gmu-10157, the skull of Yixianopterus was probably longer judging by the pre-antorbital fenestra portion and the mandible. The teeth were more widely spaced. The caudals were shorter. Fingers I-III were smaller, but the wing finger was much more robust. Manual 4.1 approached the elbow when folded and the wingtip was higher than the skull when quadrupedal. The pelvis and tibia were more robust.
Then (Perhaps) Another Size Decrease with BSp 1968 XV 132
Distinct from Yixianopterus, the skull of BSp 1968 XV 132 was longer and lower with more and smaller teeth. The mandible was similarly gracile. The cervicals were longer with tall neural spines. The torso was relatively smaller and shallower. The pectoral girdle was smaller. The humerus was longer and the entire wing was more gracile. Manual 4.1 extended only to the mid ulna. Fingers 1-3 were even smaller. The ilium was more gracile with a greatly reduced posterior process. The tibia was longer and more gracile. The pes was relatively smaller.
And Another Size Decrease with No. 30
B St 1936 I 50 (no. 30 in the Wellnhofer 1970 catalog) ~2.5 cm skull length, Late Jurassic ~150 mya. Standing ~7 cm tall, this is one of the smallest of all known pterosaurs. If it was an adult, eggs were no more than 3 mm in diameter. Much smaller than and distinct from BSp 1968 XV 132, the skull of no. 30 was relatively smaller with a shorter rostrum. The cervicals had short neural spines. The torso was longer. The sternal complex was wider. The coracoid was longer. The humerus was longer and more robust. The wing finger was more gracile. The pubis was directed ventrally. The prepubis had a large perforation. The feet were larger and digit V was especially enlarged.
A Size Increase with Cycnorhamphus
Cycnorhamphus suevicus GPIT specimen (Pterodactylus suevicus Quenstedt 1855, Cycnorhamphus suevicus Seeley 1870, no. 53 in the Wellnhofer 1970 catalog) Kimmeridgian, Late Jurassic ~150mya, ~1.3 meter wingspan, was considered species of Pterodactylus, then a ctenochasmatid. Overall much larger than and distinct from No. 30, the skull of Cycnorhamphus was more robust with a large parietal crest with a narrow frontal contribution. The anterior maxilla was slightly upturned. The teeth were longer in the anterior portion of the jaws. The eighth cervical was reduced. The torso was shorter (more compact) with a larger porportion devoted to the sacrals. The sternal complex was rounder, lacking any of the sharp corners found in No. 30. The scapula was shorter and more laterally oriented. The humerus was shorter, but the elbow still extended posteriorly just to the tip of the ilium. The metacarpals were longer as were fingers I-III. Digit III was an ungual longer than II. The pelvis was more robust. The tibia was longer in concert with the metacarpus such that the wrist and knee remained aligned. Pedal digits II and V were further elongated.
A Slightly Larger Cycnorhamphus
Formerly Gallodactylus, C. canjuersensis MNHN CNJ 71 (Fabre 1974, 1976; Bennett 1996) is about 40 per cent larger overall, had a shorter wing (not higher than the skull when folded) and a distinct coracoid and pelvis shape. The “prefrontal” of Fabré (1974, 1976) appears to be a lacrimal. The “quadrate” appears to be metacarpal 3 due to its rod-like shape, expanded distal articular surface and proximity to mc IV. The “pterygoid” appears to be the ectopalatine. The “right jugal” appears to be a quadrate due to its angle, position and simple broad shape. The “left corocoid” is a short scapula and the attached “humerus (H.d)” is a coracoid, as Bennett noted. The other “humerus (H.g)” is only half the relative size of the humerus in C. suevicus, so it appears to be another attached scapula.
Another Even Larger Cycnorhampus
A much larger private specimen known only from a skull and jaw with a peculiar vomer expanded into a half disc that fit into a bent mandible can be attributed to Cycnorhamphus, but it is a distinct species.
Feilongus youngi (Wang, Kellner, Zhou and Campos, 2005)~30 cm skull length, Barremian-Aptian, Lower Cretaceous ~125 mya, was considered a ctenochasmatid and an ornithocheirid. Larger overall and distinct from Cycnorhamphus, the skull of Feilongus had a rostrum twice as long. The dorsal margin of the skull was concave from tip to tip. More teeth that were more widely spaced lined the anterior jaws. The anterior rostrum was spoon-shaped.
As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.
Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.
Bennett SC 2010. The Morphology and Taxonomy of Cycnorhamphus. Acta Geoscientica Sinica 31 Supplement 1, The Flugsaurier Third International Symposium on Pterosaurs.
Lü J, Ji S, Yuan C, Gao Y, Sun Z and Ji Q 2006. New pterodactyloid pterosaur from the Lower Cretaceous Yixian Formation of Western Liaoning. In J. Lü, Y. Kobayashi, D. Huang, Y.-N. Lee (eds.), Papers from the 2005 Heyuan International Dinosaur Symposium. Geological Publishing House, Beijing 195-203.
Wellnhofer P 1975a. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. Paleontographica A 148: 1-33.1975b. Teil II. Systematische Beschreibung. Paleontographica A 148: 132-186. 1975c. Teil III. Paläokolgie und Stammesgeschichte. Palaeontographica 149: 1-30.