SVP 16 – Cimoliopterus [crested pterosaur], now from Texas!

Myers 2015,
famous for his basal Pteranodon/Germanodactylus, describes a new ornithocheirid with a premaxillary crest in an abstract (see below) and in a JVP paper that just came out.

From the abstract
“Cretaceous strata of Texas have yielded an unexpectedly rich collection of pterosaurs that differ substantially from the prolific, Pteranodon-dominated assemblages of the Western Interior. Two new pterosaur specimens from the Upper Cretaceous Eagle Ford Group in the Dallas/􀂱Fort Worth area enhance our understanding of the fragmentary record of Texas pterosaurs. One specimen (SMU 76892), discovered in the upper Cenomanian portion of the Britton Formation, consists of the rostral section of an upper jaw that bears a prominent, thin premaxillary crest beginning just above the fourth pair of alveoli. The preserved portion of the jaw contains alveoli for 26 teeth, and there is a subtle lateral expansion at the anterior end of the jaw. This partial rostrum is identified as a new species of Cimoliopterus, a monotypic genus previously known only from Cenomanian deposits in England, and represents a significant geographic range extension for this genus. The second new specimen from the Eagle Ford Group (SMU 76942) is a partial upper jaw of Aetodactylus halli, heretofore known only from mandibular material. The jaw fragment was collected at the type locality of A. halli in the middle Cenomanian Tarrant Formation. The dorsoventrally compressed specimen represents part of the anterior half of the jaw, although the exact position within the palate cannot be determined with certainty. The ventral surface bears a thin palatal ridge, and the dorsal surface preserves no evidence of a premaxillary crest. Patterns in tooth spacing along the upper jaw are similar to those observed in the holotype mandible of A. halli (SMU 76383). A phylogenetic analysis of Pterosauria that incorporates the new Cimoliopterus species and new codings for the upper jaw of Aetodactylus indicates that both taxa are basal pteranodontoids. Aetodactylus and Cimoliopterus appear closely related, but are clearly distinct from each other. Identification of Cimoliopterus in North Texas provides further evidence of paleobiogeographic links between the Cretaceous pterosaur faunas of North America and Europe. Discovery of the upper jaw of Aetodactylus confirms that this pterosaur lacked both premaxillary and mandibular crests.”

The Cimoliopterus rostrum
confirms earlier observations of anterior extensions of the nasal and jugal found in other ornithocheirds that extend to the secondary and tertiary nares, both vestigial pores (Fig. 1) recovered by tracing without access to the original specimen.

Destruction
of part of the right side of the rostrum reveals little strips of bone that evidently extended just below the former surface that extend from the nasal and jugal. The fused vomers are the long reported “palatal ridge” described in several ornithocheirids.

Figure 1. Click to enlarge. The rostrum of the North American Cimoliopterus. Every 2 seconds the scenes change. Pink = nasal. Lavender = jugal. Yellow = premaxilla. Green = maxilla. Violet = vomers. DGS enabled the identification of these bones overlooked by first hand observation.

Figure 1. Click to enlarge. The rostrum of the North American Cimoliopterus. Every 2 seconds the scenes change. Pink = nasal. Lavender = jugal. Yellow = premaxilla. Green = maxilla. Violet = vomers. DGS enabled the identification of these bones overlooked by first hand observation.

These extra nares originate also as pores with Scaphognathus (Fig. 2), an ancestral taxon.

Figure 1. Click to enlarge. The reduction of the naris (red arrow), the appearance of the secondary naris, and the appearance of the secondary ascending process of the maxilla in a line of scaphognathids, all to the same scale.

Figure 2. Click to enlarge. The reduction of the naris (red arrow), the appearance of the secondary naris, and the appearance of the secondary ascending process of the maxilla in a line of scaphognathids, all to the same scale. GMu 10157 is basal to the much larger ornithocheirids as recovered in the large pterosaur tree and ignored in the cladograms of other workers.

Note that Myers also traced the nasals and vomers
in Cimoliopterus (Fig. 1) without realizing what they were. That’s where DGS and a good pterosaur cladogram become valuable.

References
Myers TS 2015. New pterosaur material from the Late Cretaceous of North Texas.
Myers TS 2015. First North American occurrence of the toothed pteranodontoid pterosaur Cimoliopterus, Journal of Vertebrate Paleontology, DOI: 10.1080/02724634.2015.1014904

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