Transylvanian Dinosaurs
Page 3
NOPCSA AND ALBANIA
Although we regard Nopcsa’s studies of the Transylvanian dinosaurs as his greatest legacy, he is equally well known for his work on Albania.12 Beginning at the turn of the twentieth century, Nopcsa began a short but intense relationship with the remote Balkan country of Albania.13 He had first been introduced to the Albanian region in 1899, when he met Ludwig Graf Drasković, a lieutenant in the Austro-Hungarian Army who was returning from this part of the Balkans. Apparently it was Drasković who overwhelmed Nopcsa with thrilling stories of rugged mountains, poor but proud villagers, and blood feuds. It was not until after his graduation from the University of Vienna, however, that Nopcsa made his first trip to Albania, thanks to a graduation gift of 2,000 Austrian crowns from his uncle and namesake, Franz Baron Nopcsa (Franz Baron Nopcsa, the elder, was the First Lord Chamberlain to Elisabeth, Empress of Austria and Queen of Hungary). Traveling first through Greece in 1903, then through the eastern Balkans, Nopcsa finally made his way to Skutari (now Shkodra) in northern Albania, where he lived with a local family. His extensive travels in the mountains of northern Albania over the next 15 years provided the basis for his detailed accounts of the geology and geography of the region, which he used later in his scientific career in support of Wegener’s theory of continental drift. It also gave Nopcsa the opportunity to learn about the laws, customs, and people of this remote area of the ever-explosive Balkan Peninsula. Living with and working alongside members of the Merdite tribe, Nopcsa integrated himself into the community, amassing considerable information about the tribes of northern Albania: their history, languages, and religious practices. His major works—amounting to well over a thousand pages of text—are still considered among the most significant in Albanology.
Figure 1.4. Franz Baron Nopcsa (left) and Friedrich von Huene (1875–1969; right) inspecting the fossil-bearing, Lower Jurassic strata at Holzmaden, Germany. (Photo courtesy of Universität Tübingen, Germany)
The ethnic and political problems of today’s Balkans are deeply rooted in history, manifested, for instance, in the Balkan Wars of 1912 and 1913. At that time, the Austro-Hungarian and Ottoman empires politically dominated the region, with tensions in the northern Balkan area being especially high. No one could have appreciated this situation more than Nopcsa. He had lived with the people, learned their language and dialects, been involved in a blood feud, and was a leader of soldiers. As a stalwart supporter of Austro-Hungary, he feared Turkish and Serbian aggressions from the south and east, and sought solutions through his political connections and influence. He pushed for an independent Albania allied to Austro-Hungary, a union presumably desired because of his love for his adopted Albania and his loyalty to the Empire. He used whatever influence he could muster to sway Count Pál Teleki von Szék and Count István von Bethlen, two fellow Transylvanians destined to be successive prime ministers of Hungary, and the general chief of staff of the Austro-Hungarian Empire, Count Franz Conrad von Hötzendorff. Nopcsa’s plan was to arm the northern Albanian tribes and carry out a guerrilla war against the Turks, routing them and liberating Albania. Nopcsa also had his name put forward as a potential candidate for King of Albania in 1913, should his campaign have resulted in success. It was Prince Wilhelm zu Wied, however, who got the job, even though the latter held it for only six months before being driven out by the Albanians. The 1914 murder of Archduke Franz Ferdinand in Sarajevo was a turning point for Nopcsa; although he continued to publish his often-massive Albanian studies until his death, he was never to return to his adopted country after 1916. His involvement in the geopolitics of the Balkans did not stop with Albania, however. During World War I and immediately afterwards, he apparently also carried out espionage in western Romania under the auspices of the prime minister of Hungary, Count István Tisza.
Figure 1.5. Nopcsa’s secretary, Bajazid Elmas Doda (1888–1933; left), and Franz Baron Nopcsa (right). (Photo courtesy of the Hungarian Natural History Museum, Budapest)
It’s a pity that Nopcsa was never able to fully explore the paleobiology, paleoecology, and evolutionary dynamics of the Haţeg fauna. For on 25 April 1933, Nopcsa’s body and that of his Albanian secretary, Bajazid Elmas Doda (figure 1.5, on previous page), were found by police at their Singerstrasse residence in Vienna. A note at the scene, written in Nopcsa’s hand, made clear the last moments of the lives of these two men: Nopcsa had doctored Bajazid’s morning tea with sleeping powder and then had shot him; thereafter Nopcsa had put a gun to his own head to commit his final act.
CHAPTER 2
Dinosauria of Transylvania
At the time of Franz Nopcsa’s death in 1933, the Haţeg fauna was thought to include five dinosaurs, a bird, a crocodile, a turtle, and a pterosaur. Unfortunately, work in Transylvania went fallow after the First World War, when the defeated Austro-Hungarian Empire ceded Transylvania to Romania. It was not until the mid-1970s that the collection of vertebrate fossils resumed in the Haţeg Basin. In 1978, two teams came together to follow in Nopcsa’s footsteps. One was supervised by Dan Grigorescu from Universitatea din Bucureşti, and the other was originally organized by Ioan Groza, later supervised by one of us (Jianu) and then by us both, under the auspices of Muzeul Civilizaţiei Dacice şi Romane Deva.1 These two groups, plus a more recent joint expedition from Universitatea Babeş-Bolyai Cluj Napoca, Romania, and the Institut Royal des Sciences Naturelles de Belgique in Brussels (under the supervision of Vlad Codrea and Thierry Smith, respectively2) have ventured to the outcrops at Vălioara, Densuş, and the Sibişel Valley, as well as several new locations, this time in the Transylvania Depression—Jibou (Sălaj County) in the north and Oarda de Jos, Vurpăr, Bărăbanţ, Lancrăm, Sebeş, and Vinţu de Jos in Alba County, along the southeastern margin of the Apuseni Mountains north and east of the Haţeg Basin.3 These efforts have amassed several thousand new fossil specimens and added considerably to the diversity of the known assemblages. Several different kinds of dinosaurs are represented for the first time, as well as new bony fish, amphibians, mammals, lizards, and crocodilians. Along with this richer picture of the fauna has come a better understanding of the paleoecological context of the Haţeg Basin and other localities, as well as the evolutionary significance of this part of the world during the Late Cretaceous.4
The best-known members of the Haţeg and similar assemblages clearly are the dinosaurs. Nopcsa knew or named nearly all of them, including Telmatosaurus transylvanicus and Zalmoxes robustus among ornitho-pods, the armored Struthiosaurus transylvanicus, the sauropod Magyarosaurus dacus, and a theropod he referred to Megalosaurus, a poorly known form first identified from the Middle Jurassic of England.5 Given the Late Cretaceous age of these deposits, it is likely that many of these dinosaurs were among the last of their dynasties.
In this chapter, we hope to accomplish two things. First, we want to put members of the Transylvanian menagerie into their evolutionary or phylogenetic context. Second, we want to breathe life into the fragments of ancient bones from Transylvania and, thereby, get a meaningful picture of these beasts that once roamed the Transylvanian region. We begin by outlining a field of study called phylogenetic systematics, otherwise known as cladistics. Cladistics is used to establish who is more closely related to whom among a group of organisms. We also use it to understand the relationships of the dinosaurs and their Transylvanian cohorts along the way.
THE HISTORY OF LIFE AND HOW WE KNOW IT
Fossils are the petrified remains of prehistoric life, something that has been recognized in the scientific community for three centuries, ever since the Danish scientist Nicholas Steno (1638–1686) first interpreted fossils as the vestiges of once-living creatures. Darwin understood that the links among these organisms constituted evolution, and he postulated a mechanism for the latter that depended not on divine design, but on the day-to-day action of environment on variable individuals within a population. He also understood that evolution, by its continual production of generations of descendants from earlier descendants, from still
earlier descendants, and so on, back to primordial ancestry—in other words, diversification—was therefore hierarchical. It’s not for nothing that his canon—“descent with modification”—emphasized the hierarchical property of evolution. Others had already recognized this hierarchy in nature, most notably Carolus Linnaeus, the great eighteenth-century classifier of all organisms. His cataloging revealed that God’s creative hand had hierarchical tendencies, and all organismal taxonomies have had this structure thereafter. Darwinians and everyone since then have taken on Linnaeus’s practice of, if not his motivation for, identifying hierarchies in nature, because these nested sets of diversity conform to a single phylogeny, a single genealogy into deep time that documents the interrelatedness or connectedness of all life.
How, then, can we identify phylogeny’s hierarchy? We don’t have a written record, as we do for our personal family genealogies, but we do have the similarity of features possessed by organisms that underlie their evolutionary history. From Darwin’s time to the present, we have given special evolutionary significance to a particular class of similar features, called homologies, whose presence gives nature its hierarchical property. For a feature to be a homology, it must have evolved only once. How we determine whether a feature has a unique origin is a matter of comparison. Take, for example, the presence of retractile claws in mammals. Such claws are very anatomically and biomechanically similar to each other in all the mammals that possess them—cats, lions, tigers, and others. Here we’ve passed the first test of homology, the test of similarity. The second test is the congruence of a feature with phylogeny (i.e., with evolutionary history): can we tell if retractile claws evolved just once, instead of several times, in the groups of animals that have them? In our example, the answer is yes; all cats have retractile claws and, because we regard all of these animals as very closely related, we hypothesize that retractile claws evolved once in the group of mammals called Felidae.6 Said another way, this homology evolved once in the common ancestor of Felidae and then was passed on to its descendants. By the same token, if someone tells us that a given mammal is a felid, we would expect it to have had retractile claws, although they may have been subsequently lost. By their very nature, homologies evolve only once, and they therefore speak about the closeness of the relationship between two kinds of organisms.
By properly identifying a group of organisms as having a single common ancestor (a single origin) on the basis of its characters, we have begun determining whether that group is monophyletic. The other important aspect of monophyly is that the group contains all the descendants of this common ancestor. Seen in this way, Homo sapiens is monophyletic, felids are monophyletic, birds (Aves) are monophyletic, and Dinosauria is monophyletic. But Dinosauria without birds is not monophyletic—it leaves off some of the descendants of the common ancestor of all dinosaurs. This latter kind of grouping, known as paraphyly, is similar to leaving off Uncle Bob and his family from your family tree—you may want to, but the end result wouldn’t be a true reflection of your family history.
Figure 2.1. The founder of phylogenetic systematics (also known as cladistics), Willi Hennig (1913–1976)
The interdependence of homology and hierarchy forms the basis of what is known as cladistic analysis, a tool that is particularly well suited to reconstructing phylogeny. Cladistic methods, first developed by the German entomologist and founding father of phylogenetic systematics, Willi Hennig (figure 2.1), seek to establish the hierarchical nature of evolution by searching for the nested arrangement of organisms and the features they possess.7 This pattern is then portrayed on a branching diagram called a cladogram, with each collection of branches being referred to as a clade. The characters used to justify the branching pattern in a cladogram may have broad or limited distributions, such that some characters will diagnose more general relationships, while others will diagnose more restricted ones (figure 2.2). For example, Aves (modern birds) and Crocodylia are both diagnosed as archosaurs because of their brain-case and palate, general features that evolved once in the common ancestor of these two groups, although several aspects of these features may have later altered within the groups. More specific affinities, for example Homo sapiens and Australopithecus afarensis within Hominidae, can be assessed by identifying homologies—both possess features of the pelvis, femur, and knee that relate to their unique evolution of bipedality. In other words, a character may be specific to one group (i.e., bipedality in Hominidae), but general in a smaller subset of that group, because it is now being applied at a different position in the hierarchy.
Figure 2.2. Cladogram of Archosauria (left) and Hominidae (right)
If things were as simple as this, the task of determining phylogeny would be a snap. We would seek the nested relationships of similarities in molecules, morphology, and behavior, then interpret them as homologies, and the hierarchical history of life would be revealed. All similarities would be homologies, from which we could then reconstruct phylogeny.8 However, nature, like history, is messy—she invents similarities that are not and cannot be homologies. Take, for example, the presence of eyes in both dolphins and squid. They are not considered as having evolved just once in the common ancestor of Vertebrata and Cephalopoda; given the other features and taxa that must be considered in this comparison, eyes must have evolved at least twice to account for their distribution. Said another way, these nonhomologous similarities, called homoplasies, are not congruent with a single origin during phylogeny. Homoplasies are those features that get in the way of discovering phylogenetic patterns, because they are produced by two or more events in evolutionary history.
Figure 2.3. A hypothetical example of how to determine the most parsimonious cladogram (see text for explanation)
Let’s take a final look at how characters can be identified as homologies and homoplasies, using a hypothetical example. We have six taxa (A–F) as well as two phylogenies of these taxa that we want to test, to see which one is best supported by the features we’ve hypothesized as being homologies. In figure 2.3, the cladogram on the upper left consists of two monophyletic groups (A–C and D–F), the first supported by three homologies (characters 4–6) and the second by two (characters 7–8). Within each of these groups there is another monophyletic clade, each supported by its own homologies (characters 1–3 for the first group and character 9 for the second).
The cladogram in the upper right implies dramatically different relationships from that in the upper left. All taxa, from A to E, are sequentially more closely related to taxon F. These relationships are supported at each level by single homologies (characters 10, 11, 12, and 13), each of which is different from those that produced the cladogram to its left. We can tell which tree is likely to be correct, given the data we have, by finding out which tree is shorter. In doing so, we must use not only the data that support a given cladogram, but also all the others that don’t support it. That is, we must also account for all the characters on each tree (i.e., by applying characters 10–13 to the left tree, and characters 1–9 to the right tree). We’ve done that for the cladograms in the lower row.
Because all characters must appear on the cladogram, conflict among features is bound to occur. These conflicts in cladograms and their character support are settled by letting the possible homologies fight it out among themselves. This rather bloodless battle is carried out in the arena of parsimony, otherwise known as Ockham’s Razor. Parsimony, originally articulated by the fourteenth-century Franciscan monk William of Ockham (in England), ensures that, in the case of cladistic analyses, the simplest or shortest cladogram is chosen. In following this principle, we therefore have to select the tree supported by the greatest number of homologies from those that we originally hypothesized. This is a requirement, since homologies, the sine qua non of close relationships, are represented only once on a cladogram, but homoplasies, by their very nature, are found multiple times on the cladogram. In other words, some of our original hypothesized homologies are forced to become homoplasi
es by the weight of evidence coming from the other characters. Depending on the situation, some characters will either evolve twice or evolve and then reverse back to their more primitive condition (shown with an asterisk). Once the distribution of all the characters is determined, their positions on each cladogram are counted up. The shortest tree, which we call the most parsimonious one because it maximizes the number of homologies, is the one on the left, with a length of 15 steps. It is four steps shorter than the one on the right, which takes 19 steps to account for all the evolutionary changes in the six taxa.
THE SCIENCE (AND ART) OF COMPARATIVE ANATOMY
To understand the biology of extinct creatures (such as the denizens of ancient Transylvania) as best we can, it behooves us to do what every paleontologist must—fill in the missing bits of skeleton and teeth in a reasonable way to better understand the no-longer-living creatures we’re studying. We owe the means by which we meet this challenge to the founding father of dinosaur paleontology, Sir Richard Owen (figure 2.4), in his role as a comparative anatomist.9 Owen’s greatest achievement in this arena has become one of the most cited and mythologized of all episodes in paleontological history. In 1839, Sir Richard famously deduced the existence of an enormous flightless bird that once inhabited New Zealand, reconstructing the whole animal from a single fragment of a femur. The test of his construction—and the basis for his eminence as a comparative anatomist—came with the discovery, four years later, of well-preserved skeletal remains of the extinct moa, Dinornis maximus, a 3.5 m tall, ground-dwelling, flightless bird.10 Based not on arcane knowledge, witchcraft, manipulative card tricks, chicanery, or wild speculation, Owen’s achievement instead was due to years of studying the structure of a wide array of living and extinct animals, or what we now call comparative anatomy.