Alcmonavis poeschli – Another Late Jurassic “Early Bird”

Scientists have identified a new species of “proto-bird” which was contemporaneous with Archaeopteryx (A. lithographica).  Known from a single, fragmentary fossil, excavated from the Lower Tithonian Mörnsheim Formation of the Solnhofen Archipelago, the species has been named Alcmonavis poeschli.  Its discovery supports the hypothesis that there were numerous bird-like dinosaurs in the Late Jurassic.

The Late Jurassic of Europe Could Have Been Home to Numerous “Proto-birds”

Picture credit: Carl Buell

A Right Wing from a Volant Animal

A. poeschli is represented by a right wing (specimen number: SNSB-BSPG 2017 I 133).  The bones are partially dislocated but lying in proximal association, the fossils consist of the humerus, radius, ulna, the hand and finger bones with claws.  Although there are only a handful of bones to study, they show a number of derived characters such as a pronounced attachment area for the pectoralis muscle and a robust second finger.  These traits indicate that Alcmonavis is a more derived avialan than Archaeopteryx.

A Photograph Showing the Holotype Fossil of Alcmonavis poeschli

Picture credit: Bayerische Staatssammlung für Paläontologie und Geologie/AFP

The photograph (above), shows the wing of Alcmonavis poeschli as it was found in the limestone slab.  Alcmonavis poeschli is another example of a volant bird from the Jurassic period.  It may have been a more capable flyer than the urvogel (Archaeopteryx).  Scars on the wing bones suggest the placement of sizeable muscles, indicating that the raven-sized Alcmonavis was capable of flapping its wings with some force.

Alcmonavis poeschli

One of the authors of the scientific paper, published this week in the academic journal “eLife”, Oliver Rauhut of the Bayerische Staatssammlung für Paläontologie und Geologie (Bavarian State Collection of Palaeontology and Geology) stated:

“At first, we assumed that this was another specimen of Archaeopteryx.  There are similarities, but after detailed comparisons with Archaeopteryx and other, geologically younger birds, its fossil remains suggested that we were dealing with a somewhat more derived bird.  The wing muscles indicate a greater capacity for flying.”

This discovery indicates higher avialan diversity in the Late Jurassic than previously recognized.

Named after the Altmühl River

The genus name is derived from the old Celtic name for the Altmühl River which flows through the Solnhofen limestone region and from the Greek “avis” for bird.  The species name honours Roland Pöschl who leads fossil hunting expeditions to the Old Schöpfel Quarry, where the fossilised wing was discovered.

To read an article published in 2017 about another feathered dinosaur from Solnhofen: The Archaeopteryx That Wasn’t.

To read an article from February 2019, that explains how the iconic Archaeopteryx feather fossil was reclassified: Iconic “Archaeopteryx” Feather Not From Archaeopteryx.

Visit the Everything Dinosaur website: Everything Dinosaur.

Austrian Phytosaur Fossils Point to Phytosaurs in Marine Environments

Look at most books that feature an illustration of the fauna of the Triassic and it is likely that squeezed into the colourful but so spurious illustration of early dinosaurs, beaked rhynchosaurs and cynodonts all going about their business but effectively ignoring each other, you will spot a phytosaur.  Phytosaurs, the long-snouted, semi-aquatic carnivores that resembled crocodiles but were certainly not crocodilian, were widely distributed during the Triassic.  However, very little evidence had emerged that linked these predators with marine ecosystems.

It had been thought phytosaurs were confirmed to freshwater or brackish environments.  The publication of a new scientific paper, reporting on the discovery of the remains of at least four individuals from an ancient lagoon, represents the best evidence yet that these formidable predators also inhabited the sea.

Phytosaurs in Marine Ecosystems

Picture credit: Mark Witton (© 2019 The Linnean Society of London, Zoological Journal of the Linnean Society)

Mystriosuchus steinbergeri

Although the fossil remains were laid down in a coastal, lagoonal environment, these days, thanks to plate tectonics, the quarry site is two kilometres above sea level in a remote part of the Austrian Alps.  The fossils were found in 1980 by Sepp Steinberger, a member of a local caving club.  The species name (Mystriosuchus steinbergeri), was erected in his honour.  One of the reasons cited for the amount of time it has taken to fully study these fossils is that despite the relative abundance of phytosaur fossils compared to other Triassic vertebrates, there are not that many vertebrate palaeontologists that specialise in studying the Phytosauria.

Phylogenetic analysis positions this newly described species as the sister taxon to a clade comprising Mystriosuchus planirostris and Mystriosuchus westphali.  A study of the fossil bones indicates that the Austrian phytosaur specimens represent individuals that were at least eight years of age at the time of their death.  The palaeoenvironmental data recovered suggests that these archosaurian reptiles were living in a marine lagoon.  This provides strong evidence to support the idea that some phytosaurs may have adapted to living in saltwater as well as freshwater environments.

A Classic Triassic Diorama Depicting a Phytosaur

Picture credit: Rudolph Zallinger

How Did They Die?

Everything Dinosaur contacted one of the authors of the scientific paper, Richard Butler (School of Geography, Earth and Environmental Sciences, University of Birmingham), enquiring about the discovery of four individuals, all roughly the same age and the same size (approximately 4 metres in length), being found together.

Professor Butler commented:

“As to how these animals died and were buried together, your guess is as good as mine!  It’s a puzzle, and I don’t have an answer.  However, I think it’s very unlikely that they died together on land and were somehow washed out tens of kilometres and buried together.  I think it’s more likely that they were living in the lagoon and died near to where they were buried.  Interestingly, the fact that there are multiple individuals all of a similar size might suggest some social/group behaviour, although again it’s quite speculative.”

When asked to put into context the significance of this evidence supporting the idea of some members of the Phytosauria adapting to marine environments, Professor Butler explained that there have been a handful of occurrences of the species Mystriosuchus planirostris recorded in marine sediments in northern Italy, and the basal phytosaur Diandongosuchus was also found in a marine deposit.

Associated with Marine Deposits

These fossil discoveries have led to speculation that both these species were possibly marine animals.  However, they’ve all been isolated specimens, and in the northern Italian sequences, for example, there is evidence to indicate that fully terrestrial animals had been washed into these marine deposits.  So, in the case of these fossils,  it is plausible that rather than being examples of marine phytosaurs, these are terrestrial phytosaurs that died on land and were washed out to sea.

The Austrian phytosaur material ascribed to Mystriosuchus steinbergeri might not be the first evidence found to support a marine environment hypothesis but it does probably represent the strongest evidence found to date.

The professor concluded that if he and his fellow authors are correct, then the phytosaurs represent yet another group of tetrapods that independently invaded marine environments.

The scientific paper: “Description and Phylogenetic Placement of a New Marine Species of Phytosaur (Archosauriformes: Phytosauria) from the Late Triassic of Austria” by Richard J Butler, Andrew S Jones, Eric Buffetaut, Gerhard W Mandl, Torsten M Scheyer and Ortwin Schultz published in the Zoological Journal of the Linnean Society.

Visit the Everything Dinosaur website: Everything Dinosaur.