Spectember/Spectober 2023 #09: Things With Wings

(Apologies for the abrupt absence – I’m okay, just having everything break down at once. This is fine.)

So— back to the speculative evolution request list!

TheBigDeepCheatsy requested a “cactus-dwelling/germinating evolution of introduced rosy-faced lovebirds”:

A shaded sketch of a speculative symbiotic relationship between lovebirds and saguaro cactus. The lovebird is shown on the left, a small parrot that looks very similar to modern rosy-faced lovebird except with hints of a more mottled color pattern. The cactus is shown on the right, a large fasciated saguaro with its top fanning out into a wide "crown", with several nest holes dug into it and multiple lovebirds occupying them.

While Agapornis cheatsyi is still quite physically similar to its introduced ancestors, this lovebird has developed a close symbiotic relationship with the cactus Carnegiea ornipolis, a descendant of the modern saguaro.

Naturally fasciated, this cactus grows a splaying fan-like crown which the lovebirds excavate their shallow nest burrows into. Feeding on the cactus’ fruit in early summer, the lovebirds then disperse the seeds via their droppings – a process that significantly improves propagation chances, both due to the birds commonly foraging and defecating around suitable nurse plants and the passage through their gut speeding up germination.

Someone calling themself “LB” asked for some “flying afrotherians”:

A shaded sketch of a speculative flying tenrec. It's a bat-like animal with membranous wings supported by three elongated fingers, and a large shrew-like head with long toothy jaws and an elephant-shrew-like nose.

Elbeitandraka venenifer is a descendant of tree-climbing Malagasy tenrecs that developed gliding membranes – and its lineage is now just about achieving true powered flight.

About 25cm long (~10″), its proportionally short broad wings require it to fly very fast to generate enough lift for its weight. It mostly only actively flies when traveling between roosts and feeding sites (or when escaping from threats), alternating between gliding to save energy and flapping to recover altitude.

It’s an opportunistic omnivore, crawling around in the tree canopy foraging for vegetation, fruits, fungi, invertebrates, and the occasional smaller vertebrate, using its flexible sengi-like nose to probe around in crevices.

Much like modern common tenrecs it’s capable of hibernating for months at a time through periods of scarce food availability. It also accumulates alkaloid toxins in its body from its arthropod prey, advertising its unpalatability to predators with bold contrasting warning coloration on its wing membranes.

And here’s a combination of a couple of anonymous requests for both “flying heterodontosaurs” and “dragons with hind leg wings, a la sharovipteryx”:

A shaded sketch of a speculative flying predatory heterodontosaurid dinosaur, show both on the ground in a quadrupedal posture and in flight. Its hind legs form its main wings, with elongated outer toes supporting large pterosaur-like flight membranes. It also has a hooked beak at the front of fanged jaws, an s-curved neck, a compact fuzzy body, short forelimbs with taloned hands and small stabilization membranes, and a long vaned tail.

Inversodraco rapax is a highly specialized Jurassic descendant of heterodontosaurids that took to climbing and gliding, developing delta-wing-like membranes on their hindlimbs convergently similar to those of the earlier sharovipterygids.

Around 75cm long (~2’6″), it has unusually flexible hip joints for a dinosaur, able to splay its legs out to the sides to deploy wings supported by an elongated outer toe on each foot. Its arms form small forewings for stability, and its long tail ends in a vane of stiffened feathers that aid in steering.

Unlike its herbivorous-to-omnivorous ancestors it’s primarily a carnivore, swooping down onto small prey and grabbing it with its talon-like forelimbs.

Almost-Living Fossils Month #17 – Flowering Before It Was Cool

The Bennettitales were a group of seed-bearing plants found all around the world during the Mesozoic. They were an incredibly important part of ancient ecosystems, dominating the mid-level vegetation during the Jurassic and Early Cretaceous and making up over a third of the known plant species in some places. They came in two main varieties: the stocky cycad-like Cycadeoidaceae, mostly found in the northern continents; and the more slender branching tree-like Williamsoniaceae, which were more globally distributed. Most seem to have been around 2m tall (6′6″), but some may have reached much larger maximum sizes, perhaps as much as 15-25m (~49′-82′).

They date back to at least the Late Triassic (~230 mya), but they were already so diverse and numerous at that time that they probably originated much earlier – and very similar-looking leaves from the Permian and the Carboniferous hint that these plants may have actually first appeared at least 300 million years ago.

Their exact evolutionary relationships are still under dispute, with different paleobotanists classifying them as different types of seed-bearing plant. They’ve been traditionally placed close to the cycads due to their leaf shapes and growth patterns, but these similarities might be convergent since their complex flower-like reproductive structures and stomata instead suggest a possible evolutionary link to angiosperms or gnetophytes or “seed-ferns”.

The “flowers” of the bennettitaleans were round cup-like structures (sometimes resembling artichokes) which didn’t actually ever open up. While this would have made it very easy for them to self-pollinate, they may also have been some of the first plants to experiment with a mutualistic relationship with insects for pollination, possibly even partnering with early cupedid beetles in a similar manner to modern figs and their wasps.

Towards the end of the Cretaceous the rise of the true flowering plants seems to have started to send the bennettitaleans into decline, and the Cretaceous-Paleogene mass extinction at first appeared to have finished them off entirely. While there are a few Paleocene and Eocene-aged fossils that might be bennettitalean leaves, they’re not preserved in enough detail to tell for certain and they could actually be cycads.

But a few specimens from the Early Oligocene (~28 mya) of southeastern Australia and Tasmania have actually been identified as the leaves of a late-surviving species named Ptilophyllum muelleri. Since there were several other types of “relict” Mesozoic plants known to have still been present in the region around the same time (including horsetails and ginkgoes) it shouldn’t be much of a a surprise that the bennettitaleans had hung on there too – but sadly it’s not clear how much longer past this time they would have managed to survive. A drying and cooling climate towards the end of the Oligocene and into the Miocene, along with continuing competition from diversifying flowering plants, may have been enough to finally overwhelm these last few members of a once-impressive lineage.