the month in snapshots

 

the year in books [V]

This next batch of books in my 2020 Reading Queue are historical fiction. Gareth Hinds' The Iliad is a graphic novel retelling Homer's classic tale. Steven Pressfield took up half of this batch of books: his Gates of Fire centered around the battle of Thermopylae between the Greeks and the Persians; Tides of War focused on the life of Alcibiades in the Peloponnesian Wars; The Virtues of War told the story of Alexander the Great's conquests. Robert Harris' Dictator was the third book in his Cicero Trilogy, and Samurai Rising was a great retelling of the birth of the samurai in ancient Japan. 

Dino of the Week: Protoavis

Type Species: Protoavis texensis

Classification: Dinosauria - Saurischia - Theropoda

Time Period: Late Triassic

Location: Texas

Diet: Carnivore

Protoavis’ name means ‘first bird,’ and it hails from the Norian stage of Late Triassic Texas. This dinosaur (or dinosaur-like creature, depending on who you talk to) continues to be the topic of many collegiate barroom debates. If Protoavis is a bird, as its discoverer Sankar Chatterjee insists, then it pushes bird evolution back 75 million years from the Jurassic Period. Archaeopteryx of the Jurassic Period has been traditionally viewed as the first known bird, sprouting from theropod dinosaurs, but if Protoavis precedes it, then bird origins are pushed back to the Late Triassic. 

We don’t know much about Protoavis, because its remains are sketchy and smashed. Reconstructions picture it as a 35-centimeter tall bird that lived in modern-day Texas some 210 million years ago. It had teeth on the tip of its jaws and eyes located at the front of the skull, which suggests a nocturnal or crepuscular (‘twilight’) lifestyle. The presence of feathers is suggested, but not confirmed, by what appear to be ‘quill knobs.’ Quill knobs are the attachment points for flight feathers found in some modern birds and non-avian dinosaurs. It had a braincase similar to the later theropod dinosaur Troodon – hailed as one of the smartest of all dinosaurs – and its otic capsule may be arranged in bird-like fashion with three distinctly-arranged foramina. However, the presence of a post-temporal fenestra in the braincase is either foreign or reduced in all birds, including Archaeopteryx. The braincase has a lot of similarities to those of the coelurosaurian dinosaurs, and its hand-bones are decidedly non-avian. Despite these differences, Chatterjee and other paleontologists – though a minority – insist that Protoavis really is the first known bird. As Chatterjee writes, “The most remarkable thing about Protoavis is that, although it predates Archaeopteryx by 75 million years, it is considerably more advanced than Archaeopteryx… Protoavis is more closely related to modern birds than is Archaeopteryx.” That’s quite the statement, and it’s no surprise that the majority of paleontologists cry anathema.

Chatterjee’s detractors deny that Protoavis is a bird; they’ll argue that it’s just a weird type of archosaur, or even a ‘chimera,’ a combination of different creatures into a whole that had no basis in reality. As one paleontologist quipped, “The most parsimonious conclusion to be inferred from [the] data is that Chatterjee’s contentious find is nothing more than a chimera, a morass of long-dead archosaurs.” If he’s right, then Chatterjee’s specimen is comprised of bits and pieces of different organisms built together into a Late Triassic Frankenstein. Not all detractors believe it’s a chimera, however; many believe that Protoavis truly is a real animal from the Triassic, but they question the identification of quill knobs. Perhaps the quill knobs were actually something else! In other cases, however, those same paleontologists who decry the quill knobs on Protoavis will praise the very same thing on other creatures! Take, for example, Concavenator, which lived 130 mya and predated Archaeopteryx by about twenty million years. It, too, had ‘quill knobs’ like Protoavis, and paleontologists were more than happy to identify them as feather attachments. The magazine Nature reports, “[It] is the bumps on the dinosaur’s arms that have caused a stir: the researchers think that they may have been part of structures that anchored quills to the creature’s bones.” According to the standards applied to Concavenator, there’s no reason to question the quill knobs of Protoavis. It becomes apparent that the criticism directed towards Chatterjee has less to do with scientific reasons and more to do with philosophical ones. As Michael Benton explains, acknowledging Chatterjee’s interpretation of Protoavis’ quill knobs would wreak havoc on standard evolutionary theory: “[If] Protoavis is a bird, then the point of origin of the group [of birds] moves back to the late Triassic, and that would distort many parts of the phylogeny, not only of birds, but also of Dinosauria in general.” We can delight in the discovery of Concavenator, because it’s enlightening and invigorating; but we must resist the same rules applied to Protoavis, because doing so would put the whole ‘birds evolved from dinosaurs’ paradigm on uncertain footing. 

Of course, birds could still be evolved from dinosaurs, just far earlier than expected and from more primitive theropod stock; but it would also open the possibility that birds are ‘common ancestors’ of dinosaurs just as chimpanzees are ‘common ancestors’ of humans: we’re cousins, but not descended from one another. Many ornithologists, who don’t like the idea of birds descending from dinosaurs, trumpet Protoavis as a banner, insisting that birds found their origins with archosaurian relatives of the first dinosaurs. Thus we can see why Protoavis has become such a hot topic. Despite its detractors, however, some paleontologists do agree with Chatterjee and argue that birds still evolved from dinosaurs – but they did so in the Late Triassic around the same time that theropods were in their genesis. 

Dino of the Week: Pisanosaurus

our feathered friend Pisanosaurus

Type Species: Pisanosaurus mertii

Classification: Dinosauria - Ornithischia - Heterodontosauridae*

Time Period: Late Triassic

Location: Argentina

Diet: Herbivore

several Pisanosaurus flee a roving rauisuchian

The small, herbivorous dinosaur Pisanosaurus lived in what is now Argentina during the Carnian stage of the Late Triassic, around 228 to 216 mya. This dinosaur was lightly-built and grew to about three feet in length and probably weighed around five to twenty pounds. Pisanosaurus was found in a locale that, during its day, was a volcanically active floodplain covered by dense forests with a warm and humid climate subject to seasonally strong rainfalls. As a ground-dwelling herbivore it likely fed on ferns and horsetails, and it may have sought to hide from the fast-moving theropods Herrerasaurus and Eoraptor by seeking sanctuary in the giant conifers of the highland forests that grew up along the riverbanks. It may have competed with other Carnian herbivores such as the crocodile-like rhynchosaurs, the armored aetosaurs, and two-tusked dicynodonts. It would’ve kept a close lookout for the top predators of its day: the heavyweight rauisuchians and the dreaded pseudosuchian Sarchosuchus, the Top Dog in the volcanic basin (though given Pisanosaurus’ size and agility, it may have feared being trampled more than being hunted!).

a single Pisanosaurus seeks shelter among the giant conifers
of Argentina's Late Triassic volcanic basin

Up until 2017 Pisanosaurus was viewed by most paleontologists as the oldest known ornithischian dinosaur. Ornithischians were the ‘bird-hipped’ dinosaurs, as opposed to the ‘lizard-hipped’ saurischians. Ornithischians of the later Mesozoic included ornithopods and lambeosaurs, ceratopsians and pachycephalosaurs, and stegosaurs and ankylosaurs. The dominant dinosaurs of the Late Triassic were the saurischian prosauropods and theropods, so Pisanosaurus’ presence in the Late Triassic is important (for a long time it was thought that ornithischians didn’t appear until the Jurassic). In recent years, however, some scientists have argued that Pisanosaurus wasn’t a dinosaur at all but a silesaurid. The silesaurids were ‘wanna-be’ dinosaurs, cousins to the lineage that would eventually dominate the Mesozoic. Debate still rages: “Is Pisanosaurus the earliest and most primitive ornithischian, or is it an impostor whose family line was doomed to extinction?”

* If Pisanosaurus is not a dinosaur after all (see paragraph above!), then it's classification would be more like Dinosauriformes - Dracohors - Silesauridae

Dino of the Week: Pantydraco

Type Species: Pantydraco cadacus

Classification: Dinosauria - Saurischia - Sauropodomorpha

Time Period: Late Triassic

Location: Wales, United Kingdom

Diet: Omnivore

Pantydraco lived during the Late Triassic in the semi-humid wetlands of South Wales. Its name has nothing to do with undergarments; ‘panty’ is short for the Welsh word Pant-y-ffynnon, signifying hollow of the spring/well and refers to the quarry in South Wales where it wound found (‘draco’ means ‘dragon’). 

This Welsh dragon is known from a single species belonging to a juvenile. It had a long tail that was broad at the hips and tapered towards the end. It had a pointed head and strong jaws filled with well-developed teeth. It’s suspected to have been omnivorous, in the transitional phase between herbivorous and carnivorous lifestyles. Its forelimbs were shorter than its hindlimbs, and it was bipedal. Its clawed hands were designed for grasping and had three movable digits with a withered fourth. Though the juvenile’s estimated length is around three feet, adults may have been up to ten feet long. An adult would’ve weighed about 110 pounds. 

an artist's rendition of a feathered Pantydraco

Dino of the Week: Zupaysaurus

Type Species: Zupaysaurus rougieri

Classification: Dinosauria - Saurischia - Theropoda - Neotheropoda

Time Period: Late Triassic

Location: Argentina

Diet: Carnivore

Zupaysaurus lived during the Norian stage of the Late Triassic – between 228 to 208 mya – in what is now Argentina. It was found in what had been, in its times, a floodplain populated by several types of archosaurs and numerous sauropodomorph dinosaurs such as Riojasaurus. Zupaysaurus’ name is a combination of Quechua (Incan) and Greek words: the Incan word for ‘devil,’ supay, and the Greek word for ‘lizard,’ sauros. In Incan mythology, supay was the god of death and the ruler of the ukhu pacha, the Incan underworld. 

Zupaysaurus is known from only one specimen (a second, smaller specimen found near the specimen may or may not be the same kind of dinosaur). This bipedal predator had strong hind limbs and forelimbs designed to grasp. It was medium-sized, reaching to about thirteen feet in length from snout-to-tail. It had a rather long neck, and like the coelophysoids, Zupaysaurus had a kink in its snout between the premaxillary and maxillary bones of the upper jaw. 

note the (assumed) head-crests of Zupaysaurus

The original description of this theropod indicated that it had two thin parallel crests running along the top of its skull, similar to the later Dilophosaurus. The existence of these crests was based upon (a) skeletal anomaly – the lacrimal bones were at an upwards angle and may have served to anchor crests lost in the brutal fossilization process – and (b) the assumed relationship to Dilophosaurus, which undoubtedly had head crests (this same sort of logic has been used to attribute unsubstantiated crests to another Late Triassic theropod, Liliensternus). The presence of head-crests wouldn't be shocking, if only for the fact that many theropods - especially during the Jurassic Period - had such ornamentation. This doesn't mean, of course, that we should assume their presence on every theropod. In Zupaysaurus' case, further studies have indicated that the oddly-placed lacrimal bones may have ended up that way due to the fossilization process and weren’t a part of the living, breathing design; and other studies have indicated that Zupaysaurus, rather than being a predecessor to Dilophosaurus in the ‘dinosaur family tree,’ was actually part of a ‘sister clade’. If either one of these assertions is true, there’s no solid evidence for thin, parallel-running head crests. However, because artistic depictions tend towards the fanciful and eye-catching, it’s doubtful that the ‘non-crested’ version of Zupaysaurus will ever gain steam. 

a rendition of Zupaysaurus without the assumed head crests