[D] Sciurumimus albersdoerferi [Su] [sG] [T]
Rauhut, Foth, Tischlinger, Norell 2012
Jurassic Late Kimmeridgian
Saurischia Theropoda Megalosauridae
28 inches | 719 mm in length. Skull length 79 mm. Posterior skull height ca. 32 mm
Length of orbit 19.7 mm
Height of orbit 21.5 mm
Length of mandible 73.2 mm
Length of cervical series 69 mm
Length of dorsal series 102 mm
Length of sacrum 37.25 mm
Length of preserved caudal series 432 mm
Length of humerus 26.8 mm
Length of radius 17 mm
Length of metacarpal II 11 mm
Length of femur 50.6 mm
Length of tibiotarsus 54.2 mm
Length of metatarsal III 32.1 mm
Rygol Quarry at Painten, Bavaria, Germany
Recent discoveries in Asia have greatly increased our understanding of the evolution of dinosaurs’ integumentary structures, revealing a previously unexpected diversity of “protofeathers” and feathers. However, all theropod dinosaurs with preserved feathers reported so far are coelurosaurs. Evidence for filaments or feathers in noncoelurosaurian theropods is circumstantial and debated.
Here we report an exceptionally preserved skeleton of a juvenile megalosauroid [probably an early-posthatchling individual], Sciurumimus albersdoerferi n. gen., n. sp., from the Late Jurassic of Germany, which preserves a filamentous plumage at the tail base and on parts of the body. These structures are identical to the type 1 feathers that have been reported in some ornithischians, the basal tyrannosaur Dilong, the basal therizinosauroid Beipiaosaurus, and, probably, in the basal coelurosaur Sinosauropteryx.
Sciurumimus albersdoerferi represents the phylogenetically most basal theropod that preserves direct evidence for feathers and helps close the gap between feathers reported in coelurosaurian theropods and filaments in ornithischian dinosaurs, further supporting the homology of these structures. The specimen of Sciurumimus is the most complete megalosauroid yet discovered and helps clarify significant anatomical details of this important basal theropod clade, such as the complete absence of the fourth digit of the manus.
The dentition of this probably early-posthatchling individual is markedly similar to that of basal coelurosaurian theropods, indicating that coelurosaur occurrences based on isolated teeth should be used with caution.
The holotype specimen of Sciurumimus belongs to the private Painten collection of the Albersdörfer family, where it bears the collection number 1687. However, the scientific availability of the specimen is guaranteed by its inclusion in the register of cultural objects of national importance of Germany (Verzeichnis national wertvollen Kulturgutes). Under the Act to Prevent the Exodus of German Cultural Property (KultSchG; Bundesgesetzblatt I: 1754; 1999), the inclusion of the specimen in this list prevents its being sold outside Germany and guarantees that its repository is always known and that changes of repository must be announced. Furthermore, the type specimen of Sciurumimus albersdoerferi is deposited as a permanent loan at the municipal Bürgermeister Müller Museum in Solnhofen, Bavaria, where it also is available for additional scientific study and bears the specimen number BMMS BK 11.
Genus name refers to the scientific name of the tree squirrels, Sciurus, and means ’squirrel-mimic’—referring to the especially bushy tail of the animal | Species name honors the private collector who made the specimen available for scientific study.
The specimen of Sciurumimus possesses patches of skin and filamentous integument structures that are visible under UV light. Skin remains are preserved in the forelimb region and on the dorsal and ventral side of the tail. Differences in the reflection of UV light indicate that further skin remains probably are preserved on the surface of some bones (e.g., femur).
Unlike Juravenator and other examples of theropods in which skin remains are preserved, the patches show no evidence of a scaly surface. Filaments are preserved on the dorsal and ventral side of the trunk and on the dorsal and ventral side of the tail. However, the best preservation is on the dorsal side of the anterior midsection of the tail. Here, the filaments are extremely elongated and are dense, forming a bushy tail, as is the case in some other theropods.