"Silesauridae is an extinct clade of dinosauriformes, a group of Triassic reptiles which included early ancestors and relatives of the dinosaurs."
A large phylogenetic analysis of early dinosaurs and dinosauromorphs carried out by Matthew Baron, David Norman and Paul Barrett (2017) and published in the journal Nature recovered Silesauridae as a monophyletic sister group to Dinosauria.
https://en.wikipedia.org/wiki/Silesauridae
None of them are bipedal. One Silesaurid MIGHT be partially bipedal.
Silesauridae evolved from Dinosauriformes just like dinosaurs. Few unclassed Dinosauriformes are known, but the earliest is Asilisaurus. Asilisaurus was also quadrupedal.
And yet scientist think the ancestors of ornithischians and saurischians, the two main groups of dinosaurs, were fully bipedal. Though early saurischians are fully bipedal, the earliest ornithischians were not. No reason or explanation for the assumption is given in available literature.
Pisanosaurus has been considered the earliest known ornithischian. A 2008 study placed Pisanosaurus outside of (and more basal than) Heterodontosauridae. In this study, Pisanosaurus is the earliest and most primitive ornithischian.[4]
On the other hand, a phylogenetic analysis conducted by Agnolin (2015) recovered Pisanosaurus as a possible non-dinosaurian member of Dinosauriformes related to the silesaurids.[14] In 2017, it was again suggested that Pisanosaurus was a silesaurid.[15][16]
Pisanosaurus was only partly bipedal.
Other primitive ornithischians include Eocursor, Trimucrodon, and possibly Fabrosaurus.
https://en.wikipedia.org/wiki/Pisanosaurus
Of the three, only Eocursor is known to have been partly bipedal. No one thinks it was ancestral to any quadrupedal ornithischians.
Hedetodontosaurus is among the first ornithischians in the Jurassic, and was primarily bipedal. It was also highly specialized, even exhibiting heterodont teeth in response to niche adaptation. No one thinks it was an ancestor of later ornithichians.
Lesothosaurus and Strombergia are just as old as Hedetodontosaurus. Some scientist think the two were the same species, but one belongs to Thyreophora and the other to Neornithischia. These are the two main clades of Ornithischian. They were both bipedal, but also highly specialized. Neither are candidates for the ancestor of later Ornithischians.
Emausaurus, Scelidosaurus, Scutellosaurus are also Ornithischians as old or nearly as old at hederodontosaurs. Among them, only Scutellosaurus is thought to have been partly or primarily bipedal.
Scelidosaurus is considered basal to both stegosaurs and ankylosaurs and is firmly quadrupedal.
After Scelidosaurus , the great majority of ornithischians are quadrupedal. Late Cretaceous bipedal ornithischians are thought to have evolved from quadrupedal ancestors.
So quadrupedal Silesauridae, basal to all dinosaurs, was quadrupedal. It evolved into partly bipedal Pisanosaurus (or a sister taxon) which evolved into quadrupedal Scelidosaurus (or sister taxon) which evolved into quadrupedal ankylosaurs and stegosaurs.
So why would anyone think stegosaurs evolved from a fully bipedal ancestor? There is not a single fully bipedal candidate for ancestor of the two main clades of dinosaur, ornithischian and Saurischia. There is not a single fully bipedal ornithischian in lineage between stegosaurs and Silesauridae. But for no reason whatsover, it's considered settled science that ornithischians and saurischians evolved from a bipedal ancestor.
For shame, for shame.
A large phylogenetic analysis of early dinosaurs and dinosauromorphs carried out by Matthew Baron, David Norman and Paul Barrett (2017) and published in the journal Nature recovered Silesauridae as a monophyletic sister group to Dinosauria.
https://en.wikipedia.org/wiki/Silesauridae
None of them are bipedal. One Silesaurid MIGHT be partially bipedal.
Silesauridae evolved from Dinosauriformes just like dinosaurs. Few unclassed Dinosauriformes are known, but the earliest is Asilisaurus. Asilisaurus was also quadrupedal.
And yet scientist think the ancestors of ornithischians and saurischians, the two main groups of dinosaurs, were fully bipedal. Though early saurischians are fully bipedal, the earliest ornithischians were not. No reason or explanation for the assumption is given in available literature.
Pisanosaurus has been considered the earliest known ornithischian. A 2008 study placed Pisanosaurus outside of (and more basal than) Heterodontosauridae. In this study, Pisanosaurus is the earliest and most primitive ornithischian.[4]
On the other hand, a phylogenetic analysis conducted by Agnolin (2015) recovered Pisanosaurus as a possible non-dinosaurian member of Dinosauriformes related to the silesaurids.[14] In 2017, it was again suggested that Pisanosaurus was a silesaurid.[15][16]
Pisanosaurus was only partly bipedal.
Other primitive ornithischians include Eocursor, Trimucrodon, and possibly Fabrosaurus.
https://en.wikipedia.org/wiki/Pisanosaurus
Of the three, only Eocursor is known to have been partly bipedal. No one thinks it was ancestral to any quadrupedal ornithischians.
Hedetodontosaurus is among the first ornithischians in the Jurassic, and was primarily bipedal. It was also highly specialized, even exhibiting heterodont teeth in response to niche adaptation. No one thinks it was an ancestor of later ornithichians.
Lesothosaurus and Strombergia are just as old as Hedetodontosaurus. Some scientist think the two were the same species, but one belongs to Thyreophora and the other to Neornithischia. These are the two main clades of Ornithischian. They were both bipedal, but also highly specialized. Neither are candidates for the ancestor of later Ornithischians.
Emausaurus, Scelidosaurus, Scutellosaurus are also Ornithischians as old or nearly as old at hederodontosaurs. Among them, only Scutellosaurus is thought to have been partly or primarily bipedal.
Scelidosaurus is considered basal to both stegosaurs and ankylosaurs and is firmly quadrupedal.
After Scelidosaurus , the great majority of ornithischians are quadrupedal. Late Cretaceous bipedal ornithischians are thought to have evolved from quadrupedal ancestors.
So quadrupedal Silesauridae, basal to all dinosaurs, was quadrupedal. It evolved into partly bipedal Pisanosaurus (or a sister taxon) which evolved into quadrupedal Scelidosaurus (or sister taxon) which evolved into quadrupedal ankylosaurs and stegosaurs.
So why would anyone think stegosaurs evolved from a fully bipedal ancestor? There is not a single fully bipedal candidate for ancestor of the two main clades of dinosaur, ornithischian and Saurischia. There is not a single fully bipedal ornithischian in lineage between stegosaurs and Silesauridae. But for no reason whatsover, it's considered settled science that ornithischians and saurischians evolved from a bipedal ancestor.
For shame, for shame.
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