Oldest known tracks of birds dinosaur ancestors found in Africa

Exminer.com National: Oldest known tracks of birds dinosaur ancestors found in Africa

Paleontologists from Germany and Niger (Africa) reported the discovery of the oldest known records of paravian maniraptorans and of didactyl theropod tracks from Africa on February 14, 2011, at the Public Library of Science web site.

Paravian maniraptorans and of didactyl theropods are thought to be the link between birds and dinosaurs. There is a lively argument concerning the relationship.

"Overall features of Paravipus tracks imply an unknown Gondwanan member of the paravian clade Deinonychosauria as a possible trackmaker, but there is no record of a medium sized mid-Jurassic deinonychosaur from southern continents yet. Paravipus tracks provide evidence that digit II was modified in the trackmaker (and not the result of pathology or injury), with only the posterior part of digit II involved in weight-bearing during locomotion. This is a unique feature in tracks of Middle to Late Jurassic age. The modification of digit II with a hyperextensible joint seemed to have evolved much earlier in the phylogeny of paravian maniraptorans than previously expected." 　

Abstract
Background
A new dinosaur tracksite from Middle Jurassic sediments of the Irhazer Group on the plains of Agadez (Rep. Niger, northwest Africa) revealed extraordinarily well preserved didactyl tracks of a digitigrade bipedal trackmaker. The distinct morphology of the pes imprints indicates a theropod trackmaker from a paravian maniraptoran closely related to birds.

Methodology/Principal Findings
The early age and the morphological traits of the tracks allow for description of the new ichnotaxon Paravipus didactyloides. A total of 120 tracks are assigned to 5 individual trackways. The ‘medium-sized’ tracks with an average footprint length of 27.5 cm and footprint width of 23.1 cm are deeply imprinted into the track bearing sandstone.

Conclusions/Significance
A comparison with other didactyl tracks gives new insights into the foot morphology of advanced maniraptoran theropods and contributes to knowledge of their evolutionary history. The new ichnotaxon takes an important position in the ichnological fossil record of Gondwana and the mid-Jurassic biota worldwide, because it is among the earliest known records of paravian maniraptorans and of didactyl theropod tracks from Africa.

Citation: Mudroch A, Richter U, Joger U, Kosma R, Idé O, et al. (2011) Didactyl Tracks of Paravian Theropods (Maniraptora) from the ?Middle Jurassic of Africa. PLoS ONE 6(2): e14642. doi:10.1371/journal.pone.0014642