Rhamphorhynchus muensteri
- 演化之聲
- 2 days ago
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Age
Jurassic（Tithonian）
150.8-148.5 Ma
Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Order: Pterosauria
Family: Rhamphorhynchidae
Genus: Rhamphorhynchus
Species: Rhamphorhynchus muensteri
Morphological description
Rhamphorhynchus muensteri is a long-tailed pterosaur represented by numerous well-preserved specimens, allowing detailed assessment of its ontogenetic development. Across its growth series, the proportions of most skeletal elements remain relatively consistent, indicating near-isometric growth. The anterior portion of the rostrum is edentulous, whereas the posterior region bears approximately 34 teeth in total, with each side of the skull comprising four teeth in the premaxilla, six in the maxilla, and seven in the dentary. The anterior teeth are elongate and project anterolaterally, with the fourth premaxillary tooth being particularly large and positioned more laterally than the others. Posterior teeth are shorter and oriented more vertically.
The orbit is conspicuously larger than both the external naris and the antorbital fenestra. The first wing phalanx is the longest element of the wing finger and is approximately equal in length to the skull. Comparisons between juveniles and adults indicate several ontogenetic changes: adults possess proportionally smaller orbits, relatively enlarged lower temporal fenestrae, and a reduced mandibular symphysis. In addition, the teeth of some adult individuals show a more pronounced lateral compression than those of juveniles.
The wing membrane is composed of dorsal and ventral integumentary layers surrounding a common subdermal core. Actinofibrils develop within the dorsal epidermis adjacent to a layer of linear collagen fibers in the dorsal dermis. Together, these structures form the principal functional framework of the wing membrane, conferring a degree of stiffness to the dactylopatagium. As a result, the membrane is largely inextensible and likely folded along discrete, structurally defined lines.
Etymology
Genus name Rhamphorhynchus is derived from the Greek rhamphos, meaning "beak," and rhynchos, meaning "snout" or "rostrum."
Species name muensteri honors the German nobleman and fossil collector Georg Graf zu Münster.
Biological description
Rhamphorhynchus muensteri is among the most extensively studied pterosaurs, owing to its exceptionally rich fossil record. Specimens originate from the Late Jurassic Solnhofen limestones of southern Germany, where preservation conditions have yielded a large number of individuals spanning a broad ontogenetic range, from very small juveniles to large, fully grown adults. Wingspans range from approximately 0.29 m to about 1.72 m, with a recently described specimen approaching 1.8 m. The abundance and completeness of these specimens have made this taxon a key model for investigating intraspecific variation, flight performance, growth dynamics, and aspects of behavior.
With respect to flight capability, this species exhibits near-isometric growth of the wings throughout ontogeny. Unlike many extant flying vertebrates, in which juveniles possess proportionally underdeveloped wings, the consistent proportions observed in Rhamphorhynchus suggest that individuals may have been capable of powered flight at a very early stage, potentially shortly after hatching.
However, this interpretation has been challenged by histological evidence. A study by Edina Prondvai and colleagues (2012) demonstrated that early juveniles possess abundant fibrolamellar bone, indicating a rapid initial growth phase. This phase persists only until individuals reach approximately 30–50% of adult wingspan and 7–20% of adult body mass, after which growth slows considerably. This transition is marked by the presence of parallel-fibred bone and lines of arrested growth within the cortex. Based on these findings, the authors questioned the hypothesis that hatchlings were immediately capable of flight, proposing instead that powered flight may have been acquired only after reaching a certain level of somatic maturity. Rapidly growing juveniles may therefore have required parental care, or alternatively may have been independent but non-volant, possibly arboreal, organisms during early life stages.
Rhamphorhynchus muensteri has traditionally been interpreted as primarily piscivorous, and this view is supported by multiple lines of evidence. Nevertheless, recent discoveries indicate that its diet was more diverse. Hoffmann et al. (2020) described a well-preserved coleoid cephalopod, Plesioteuthis subovata, containing an embedded tooth of Rhamphorhynchus within its mantle tissue. This provides direct evidence of predator–prey interaction and demonstrates that this pterosaur preyed upon soft-bodied cephalopods. The authors further suggested that the attack likely occurred at or near the water surface. Additional studies propose that, beyond fish, Rhamphorhynchus may have opportunistically consumed other vertebrates and invertebrates, and that dietary preferences may have shifted during ontogeny.
Fossil assemblages from Solnhofen consistently show a predominance of small individuals and a relative scarcity of large adults. Histological analyses have revealed that osteologically mature individuals can vary considerably in body size, suggesting the presence of developmental plasticity. This implies that adult body size was not fixed but instead varied among individuals, potentially influenced by genetic and environmental factors. Consequently, some of the smaller specimens may represent mature individuals rather than juveniles, and this variation may also be related to sexual differences within the population.
（Author: Shui-Ye You）
References
Bennett SC. (2016). New interpretation of the wings of the pterosaur Rhamphorhynchus muensteri based on the Zittel and Marsh specimens. Journal of Paleontology.
Habib MB et al. (2024). Intraspecific variation in the pterosaur Rhamphorhynchus muensteri—implications for flight and socio-sexual signaling. PeerJ.
Hoffmann R et al. (2020). Pterosaurs ate soft-bodied cephalopods (Coleoidea). Scientific Reports.
Hone DWE et al. (2020). Unique near isometric ontogeny in the pterosaur Rhamphorhynchus suggests hatchlings could fly. Lethaia.
Hone DWE and McDavid SN. (2025). A giant specimen of Rhamphorhynchus muensteri and comments on the ontogeny of rhamphorhynchines. PeerJ.
Prondvai E et al. (2012). Life History of Rhamphorhynchus Inferred from Bone Histology and the Diversity of Pterosaurian Growth Strategies. PLOS One.
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