Delayed Dispersal of Giant Tyrannosaurs

Even the largest tyrannosaurs were not able to radiate into all habitats initially. Spreading required the means to deal with all survival strategies of potential prey, which varied by region. An initial lack of some abilities excluded big tyrannosaurs from some environments. Their apparent presence in one, the Amur, may be misleading.

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Giant tyrannosaurs decimated herbivore communities. When T. rex appeared, centrosaurines vanished. Lambeosaurs were also adversely affected.

Crested beasts survived only in areas lacking Tarbosaurus or Tyrannosaurus. The Zhucheng, Nemegt and Hell Creek faunas were bereft of lambeosaurs. Crested taxa waned when archpredators required emphasis on escaping, not mating calls. Elaborate crests evolved for intraspecific interaction. They limited what a lambeosaur could invest in means of evasion. Only where (or for as long as) super-tyrannosaurs were absent could lambeosaurs endure.

There is, however, an apparent exception. Dated to 70-68 Ma, the Amur localities have yielded abundant and diverse lambeosaurs. Olorotitan, Charonosaurus etc apparently thrived even though their region does not appear to have been a refugium. Researchers have found tyrannosaur remains, mostly teeth, in local strata. A few of these, notably a 130mm tooth crown, suggest a tyrannosaur the size of T. rex. Considered autochthonous, the material suggests lambeosaurs survived a giant tyrannosaur. That would falsify a predatory role in the demise of crested taxa.

The evidence may be misleading, however. Inasmuch as most of the tyrannosaur teeth are far smaller than 130mm, an Albertosarus--sized taxon may have been the actual top predator. Based on a tooth, the name Albertosaurus periculosis may be valid. The North American Albertosaurus was a contemporary. In this scenario, giant hunters lived in an adjacent region and only enterd the Amur occasionally, in times of stress.

The Amur may have replicated the older Laiyang community. In the Zhucheng environment Zhuchengtyrannus, and another tyrannosaur, battled huge prey, notably Shantungosaurus and a sauropod. In addition, they faced the horned Sinoceratops. Local predators specialized in prey capable of standing its ground. In contrast, the coeval Laiyang environment had no sauropods and only average sized hadrosaurs, including the crested Tsintaosaurus. Almost certainly, these taxa fled. Interestingly, instead of Zhuchengtyrannus, Laiyang had a modest-sized hunter, Chingkankousaurus. Like American counterparts, it probably sped after its quarry.1

A similar situation could've prevailed in the Amur. Perhaps the big tyrannosaur was out of its element there. Evidence for this is the similarity of the 130mm tooth to Zhuchengtyrannus dentition. Unlike Tarbosaurus or Tyrannosaurus, Zhuchengtyrannus was probably noncursorial. Bitten hadrosaur tails prove Tyrannosaurus raced after prey. Facing giants instead of fleeing taxa, Zhuchengtyrannus evolved differently. This argues it usually avoided the Amur as well as Laiyang, where smaller, fleet tyrannosaurs filled the hadrosaur hunter niche.

Then why is Zhuchengtyrannus found in the Amur? Probably because of droughts. Sauropod (and giant hadrosaur) habitats tended to be drier than most hadrosaur environments. The latter were riparian or close to rivers. Naturally, in times of drought, the sauropod/big tyrannosaur habitats tended to dry up first. This caused Zhuchengtyrannus, and some sauropods, to enter the Amur region in search of food and water. The scent of water, and carcasses from mass mortality events, probably lured them. Their presence in the Amur, however, was only intermittent and brief. They were not adapted to the area hence not true denizens of it.

Initially, the super-tyrannosaurs of Asia were like Tyrannosaurus, arising in sauropod habitat. They spread to, and affected, the regions with medium-sized prey only gradually. To do that a giant tyrannosaur had to be cursorial. Evolving rapidity, however, was not easy for a bulky, giant predator. It took time, and environments with selection pressure for speed as well as prowess. The Nemegt and the Alamosaurus habitats had average-sized hadrosaurs as well as sauropods. Therefore, Tarbosaurus and Tyrannosaurus evolved to pursue as well as battle prey. The ability to chase facilitated dispersal, or expansion of ranges. In contrast, the original habitat of Zhuchengtyrannus required just bulk and ferocity. Lacking cursoriality, it could not effectively spread--at least not in the period documented in Asia.

The inability of some giants to pursue was likely only temporary. Just as Tyrannosaurus spread to the ornithiscian dominated areas, leaving exctinction and escalation in its wake, the same scenario was likely repeated in Asia.

Even the stratigraphically highest Amur localities, such as Blagoveschensk, are probably separated from the K-Pg by a disconformity of 2 million years. The Amur record terminates roughly 68 Ma. In North America, the lambeosaur Hypacrosaurus survived to about the same time. Since the record of the last 2 million years of the Cretaceous is extant in North America, the radical alteration of communities is clearly observable. This is not the case in the Amur region, so the survival of its lambeosaurs to the end is generally taken for granted. Since Asian tyrannosaurs ultimately could've replicated the spreading of T. rex, lambeosaur survival to the K-Pg could be illusory.

1. The presence of Pinacosaurus at Laiyang also argues it lacked big, derived tyrannosaurs, even though they were present in nearby Zhucheng habitat. By about 72 Ma Pinacosaurus had disappeared with the advent of Tarbosaurus, replaced by larger and better armored defenders such as Saichania and Tarchia.

The Imperial Golden Age

Bust of Antoninus Pius, Roman emperor 138--161 CE

The middle of the second century, when Pius ruled, is often considered the height of Roman or Classical civilization. The years from 138-161 were a time of peace on the frontiers, internal stability and prosperity. The Pax Romana was at its most secure. Impressed by the Roman achievement, the Greek orator Aristides delivered a speech in praise of the Empire. Aristides spoke in the Antheneum in Rome and his audience may have included the emperor Pius. Some excerpts:

"The world speaks in unison like a chorus, and so well does it harmonize under its chorus master it joins it in praying for this empire to last for all time."

"Like one continuous country and one race, all the world quietly obeys. Everything is carried out by command or nod, and it is simpler than plucking the string of a lyre."

"It is you that have best proved the general assertion that Earth is mother of all and common fatherland. Now indeed it is possible for anyone, hellene or non-hellene, to go anywhere he wants with or without his property as if he were passing from homeland to homeland. Homer said Earth common to all, and you've made it come true."

Before the rule of Zeus, as the poets say, everything was in faction, uproar, chaos. But when Zeus came to rule everything was put in order. So too, in light of the situation before you and under you, one may suppose that before your Empire everything was in faction, topsy turvy and completely disorganized. But when you took charge faction and confusion ceased, and Universal Order shone like a glorious light on the public affairs of mankind."

"As on a holiday, the civilized world lays down the weapons that were its ancient burden, and turns to all manner of adornment and glad thoughts with the power to realize them. Cities glisten with radiance and charm, and the entire Earth has been made beautiful like a garden. Like a perpetual sacred flame, the celebration is unending."

Of course the Imperial Golden Age didn't last. Marcus Aurelius, the successor of Pius, faced serious crises and they were a mere foretaste of third century catastrophes. But the reign of Pius must rank as one of the great ages of mankind. Two thousand years later, Gibbon wrote that "If a man were called upon to name that period of history during which the condition of the human race was most prosperous and happy he would, without hesitation, name that which elsapsed from the death of Domitian to the accession of Commodus. The vast extent of the Roman Empire was governed by absolute power, under the guidance of virtue and wisdom." Pius exemplified that Golden Age.

March 1943: Missed Opportunity

The best month for U-boats fighting North Atlantic convoys wasn't early in the war but rather late--March 1943. "Gray wolves" scored against six eastbound convoys, sinking a total of 40 ships. The greatest success was achieved during the battles with convoys HX 229 and SC 122. Twenty two merchant vessels were sent to the bottom. Alarmed, Churchill was determined to redouble efforts against the reich's submarines, and sink one of every three that left port.

The German success of March 1943 has been exaggerated by some historians, who claimed it came close to severing the Allied supply line in the North Atlantic. Prior to Blair's second volume, which challenged the claim, it was common to assert that the reich came close to winning the Battle of the Atlantic. In fact, as Blair noted, the losses of March 1943 represented only about 8% of allied ships sailing that month in eastbound convoys.

The significance of the German success may have have been overblown. Is it possible, though, the Germans could have won the Battle of the Atlantic, even if they did not?

In The U-Boat Wars, Edwin Hoyt covered March 1943 in the chapter "The Jaws of Victory." Like a number of other authors, Hoyt considered the situation, after "the enormity of the disaster," to be "very black indeed." It wasn't that bad, but Hoyt included something which suggests the Allied situation could've become significantly worse.

During the pivotal battle against HX 229, Hoyt wrote that at one point the convoy was defenseless as its escorts were all busy rescuing survivors or chasing U-boats. Yet, despite a golden opportunity to inflict more losses, "four perfectly sound U-boats failed to attack." He did not say which U-boats they were; perhaps U-228, U-439, U-448 and U-445. None seem to have had aggressive commanders as they never hit anything. But what if they did attack? Given lack of escorts, it wouldn't have been difficult for the four to sink an average of two each, or 8 total. That would've doubled the score that night (March 16-17). Even as escorts returned or reinforcements came, the need for additional rescue operations would've prolonged the defenseless state of the convoy. If this situation persisted another 48 hours--until dawn on the 19th, when U-boats broke off attacks--HX 229 might've been annihilated. Instead of sinking a total of 13 ships the Germans might've sunk over three dozen. They had no shortage of boats; over 40 were available to fight HX 229 and SC 122. Destruction of the former would've boosted the total loss to about 45 ships, or over twice the historical toll. The total haul for March (just HX/SC convoys) would've been around 65.

Destruction of an additional 25 ships wouldn't have won the war. Even worse than the material losses, however, would've been the psychological blow. Annihilation of a whole convoy would've undermined faith in the convoy system. It could've badly hurt morale. After a slaughter like that, at the first sign of U-boats, many ship masters would've ordered their vessels to leave their convoys. Sinkings might've remained high even in the spring when, historically, the U-boat casualties of "Black May" effectively decided the Battle of the Atlantic. That could've been avoided, or mitigated.

Origin of the Sauropod Hiatus

For over 60 million years North America harbored sauropods. At times, the iconic beats attained gigantic size, high diversity and ecological dominance. Even after the demise of Morrison forms, Mierasaurus, Cedarosaurus and others document the survival of North American sauropods to the Cenomanian. The group then vanished, however, not to reappear until middle Maastrichtian time. Sauropods remained absent for almost the entire late Cretaceous (roughly 98 to 69 Ma).

What caused this loss of sauropods, known as the North American sauropod hiatus? Locally, two factors doomed the group. The first, or primary cause, was the late Albian highstand. Just prior to the end of the Early Cretaceous, sea levels rose precipitously, inundating a great deal of land and habitat. Naturally the most severely affected taxa were the largest ones, requiring the most habitat and food resources. No doubt, a key victim was the huge Abydosaurus. Existing just prior to Mussentuchit or Cenomanian time, Abydosaurus was bereft of resources needed for survival and died out. This extinction, however, did not mark the onset of the hiatus.

The lower horizon of the Mussentuchit has yielded tiny sauropod teeth. These teeth indicate the presence of a dwarf sauropod probably related to Astrodon. At a time of greatly diminished resources, only a diminutive sauropod, requiring minimal habitat and food, could persist. The lower Mussentuchit taxon certainly outlasted the giant Abydosaurus. It did not not last much longer, however. The highstand was to ultimately prove fatal, for the survival prospects of a small sauropod were not good.

The Mussentuchit documents an influx of Asiatic taxa into North America. Among these were Eolambia a hadrosauroid. Naturally the Mussentuchit sauropod was a low feeder. It could not reach the higher tree foliage. Dependent on low vegetation, it now faced competition from ornithopods. Even worse, it may have faced a large predator, Siats. Generally sauropod behemoths had little trouble surviving theropods, even big ones. In contrast, the little taxon stood no chance. Faced with invasive species, it appears to have succumbed quickly. The little sauropod existed just prior to the hiatus.

The fact a dwarf sauropod survived the Albian highstand, however briefly, indicates sea level changes were not the actual cause of extinction. Most likely, competitors and predators were. Nevertheless, by compelling sauropods to become small, the highstand effectively doomed them. Unless they were island dwellers, inaccessible to competitors or dangerous hunters, they lived on borrowed time.

Astrodon, a close relative of the later, Mussentuchit astrodont.

Investigating the Martian Atmosphere 1931

Spectroscopic studies have long been a means to determine the atmospheric composition of planets. From the start, there was a problem, however: distinguishing the gases of another planet from those of Earth's atmosphere.

An old c 1940 work, The Story of the Starry Universe, mentioned this problem in regards to studies of the Martian atmosphere, and the solution. Two Mt Wilson astronomers, Walter S. Adam and Theodore Dunham jr, used "very high dispersion." The book did not go into detail on the method employed, which involved the Doppler effect. The astronomers timed their observations to make the best use of it.

January 1931 witnessed an aphelic opposition of Mars. The Red Planet was virtually at its greatest distance from the sun, which slowed its orbital speed. At the same time, Earth had just passed the perihelion point of its orbit, which meant it was orbiting the sun at virtually maximum speed. Since Mars was moving at its slowest while Earth was at its fastest, the Red Planet was receding from Earth at its most rapid rate. Mars always moves more slowly than Earth, but in January 1931 it was falling behind, i.e. moving away, more quickly than usual. Under those circumstances, the spectrum of Mars was redshifted. The Doppler effect was sufficient to separate the Martian absorption lines from those of Earth (or its atmosphere).

No doubt, Adam and Dunham noted the presence of CO2 in the Martian atmosphere, as CO2 is its primary constituent. Almost certainly, they also detected H2O.

On Mars as on Earth, aphelion coincides more or less with the onset of northern summer. The north polar cap of Mars wanes, releasing large quantities of water vapor. Owing to the limited heat received while Mars is farthest from the sun, polar ice does not melt. It does however sublimate. H2O forms wispy clouds drifting southward. The research of Adams and Dunham may have been well-timed to detect water.

Yet based on the limited evidence available, the researchers also concluded the Martian atmosphere was quite thin. This realization doused cold water on claims of an inhabited Red Planet.

Mars during its latest aphelic opposition (January 2025). Mars presumably looked like that when at opposition on January 27, 1931. Note the wispy clouds extending from the pole southward, as Martian ice sublimates and drifts away.

Alleged Airstrikes 1973

The 1973 war began with air attacks on Israeli positions in Sinai and the Golan heights. About 200 Egyptian and 100 Syrian jets participated in these attacks. Most accounts of the Syrian raids indicate they were confined to the Golan. There is a notable exception, however. In Volume 5 of the ARAB MIGs series, Cooper et al. include accounts of SAF attacks inside Israel proper and even as far as the southern West Bank.

Thirty-six Syrian jets supposedly carried out these "deep penetration" raids. Twenty-four MIG-17s are said to have struck HAWK sites near Kfar Giladi and Tiberias, and also hit the Electronic Warfare (EW) center of the IDF Northern Command at Rosh Pina. In addition, it is claimed, 12 SU-20 fighter bombers, escorted by 8 MIG-21s, blasted the IDF/Air Force control center at Hebron in the West Bank.

Strangely, even though the reports are considered factual, no source corroborates them or mentions any results. No Palestinian from Hebron, no Israeli along the flight paths of the putative missions, or airmen presumably sent to intercept them, have ever confirmed these missions took place.

The alleged strike on a target in Hebron, in particular, doesn't appear to be credible. Syrian ORBAT data from Volume 5 indicates Syria's SU-20s (54 Squadron) were based at T-4, north of Damascus. That's pretty far from Hebron. The limited range of Soviet made aircraft would've been a problem, especially if the SU-20s were carrying bombs. A worse issue was the extremely risky nature of such a mission. To reach Hebron, 54 Squadron had to fly farther south than major Israeli airbases, notably Ramat David and Tel Nov. Almost certainly, Israeli interceptors from those bases, and others, would've intercepted 54 Squadron and its escorts. IAF Mirages would've shot down several jets and forced the others to jettison their bombs and flee. Even if there was no resistance before the AF control center was hit, the SU-20s and MIGs would've suffered losses on the way back. To improve morale in the dark first days of the war, the Israelis would've displayed wreckage from their kills. It's noteworthy that even in Sinai, where few Israeli Mirages were based, the defenders had two successes. They downed four SU-7s in one action and 7 jets in another, near Sharm el Sheik. Lack of similar reports from the northern front argues the putative missions are fictitious. They probably came out of a Syrian's imagination, long after the war. Even Cooper et al hint the attacks are bogus since they wrote no information about their results is known from any source.

An Su-20 jet.

Positions of Mercury

Back in the '70s I assumed that whenever an inferior planet reaches maximum elongation (east or west) the radius vector of the planet is perpendicular to that of Earth. Logically, it seemed, the two radius vectors form a right angle whenever the angular distance of Mercury (or Venus) from the sun, as seen from Earth, is at its greatest. For example, if Mercury is at greatest western elongation when Earth is at heliocentric longitude 270 degrees, Mercury "must" be at heliocentric longitude 180 degrees. To appear farthest from the sun, I imagined, the radius vector of Mercury couldn't be less than 90 degrees away from Earth's, since the planet wouldn't be fully elongated to one side of the sun.

As the diagram above makes clear, this reasoning was fallacious. Maximum elongation doesn't occur when the radius vectors form a right angle. It occurs when they form an acute angle. The separation of the two radius vectors, at farthest elongation, is far less than the "logical" 90 degrees. It's only about 60 degrees. A line from Earth to Mercury (when at maximum elongation) and beyond is farther from the sun than an Earth-Mercury line when the radius vectors are perpendicular. That proves the angle between Mercury and the sun, as seen from Earth, is not at its greatest when the radius vectors are 90 degrees apart.

Why does reality, in this case, seem to defy logic? It's due to varying distances. When the radius vector of Mercury is perpendicular to Earth's, the planet is farther away from us than it is when at greatest elongation. When the planet is farther its angular distance from the sun appears less. Conversely, when it is nearer its angular separation is greater. If Mercury was much farther away its separation from the sun would be much smaller; if the distance were vast the two bodies would appear to merge. So it's not surprising the angular sun-Mercury distance appears greatest when the planet is closer to Earth, instead of when its radius vector is 90 degrees from ours.

Addendum I

When Mercury is at full elongation its radius vector is perpendicular to a line from Earth to Mercury. But that's irrelevant. A line from Earth to Mercury is not a radius vector (a line from planet to the sun).

Addendum II

This fall marks the 20th anniversary of the blog! It's great to see it's still extant and receiving more pageviews than ever. Thanks to all who contributed over the years!