Archaeornithoides

Archaeornithoides Temporal range: Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Skull reconstruction, known material in brown
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Family:	†Troodontidae
Genus:	†Archaeornithoides Elzanowksi & Wellnhofer, 1992
Type species
†Archaeornithoides deinosauriscus Elzanowski & Wellnhofer, 1992

Archaeornithoides is a

The generic name (Archaeornithoides) means “shaped like an ancient bird” in Ancient Greek, from ἀρχαῖος, archaios, "ancient"; ὄρνις, ornis, "bird"; and εἶδος, eidos, "form". The specific descriptor deinosauriscus, "little dinosaur", alludes to the animal's small size for a dinosaur.

The

The holotype of Archaeornithoides was a very small individual. The head fragment as preserved measures just twenty-seven millimetres in length, indicating an original skull length of about five centimetres. The body length was estimated at fifty to sixty centimetres,[3] making the Archaiornithoides type one of the smallest known non-avian dinosaurs. Adult length is uncertain.

The snout of Archaeornithoides features a long antorbital fenestra, stretching over three quarters of the length of the maxilla. The maxilla bears at least eight teeth. These are small, conical and smooth, lacking wrinkles, serrations or carinae. The palatine bone seems to show the presence of a secondary fenestra.^[3]

Classification

Elżanowski & Wellnhofer (1993) claimed that Archaeornithoides was the closest known relative to birds or

Some scientists had suggested that the juvenile specimen of Archaeornithoides may belong to a previously known species of Mongolian troodontid, either Saurornithoides or Byronosaurus. However, studies of a juvenile Byronosaurus skull showed that theropod dinosaurs possess many distinctive adult characteristics even as hatchlings or embryos, and that the lack of characters solidly linking Archaeornithoides to known adult specimens shows that it is probably a distinct species. Bever and Norell (in 2009) found no evidence to support the placement of Archaeornithoides close to Avialae, and only weak support for the idea that it is a juvenile troodontid.^[5]

Paleobiology

Paleopathology

Elzanowski and Wellnhofer noted that the specimen has distinct bite marks while the back of the head fragment was ragged, and suggested that the jaws were bitten off from its braincase by a Deltatheridium mammal the size of a weasel (adding that these are common in the Bayn Dzak assemblage).^[3] Clark and colleagues (2002) noted that it may have also passed through the digestive tract of the predator before fossilization. If true, this may be the first known evidence of Mesozoic mammals feeding on dinosaurs (see Repenomamus).

References