The Story of the Dinosaurs in 25 Discoveries: Amazing Fossils and the People Who Found Them by Don Prothero is available now for pre-order, and is expected to hit the shelves in mid July. It will provide excellent summer reading!

You know of Prothero because of his many books including the current classic (now in its second edition) Evolution: What the Fossils Say and Why It Matters. The “25” genera includes The Story of the Earth in 25 Rocks: Tales of Important Geological Puzzles and the People Who Solved Them, and The Story of Life in 25 Fossils: Tales of Intrepid Fossil Hunters and the Wonders of Evolution.

This book has a chapter devoted to each discovery. The nature of the discovery varies, and the definition of discovery is, necessarily and helpfully, very wide ranging. In many cases, the discovery, recovery, eventual reporting or publication, and integration of a dinosaur species is a long and drawn out process involving multiple field trips, many different characters, and a lot of action. For example, the “discovery” of spinosaurus (from Egypt) comes to us as a story involving two world wars, several expeditions, great human tragedy, and some cool dinosaur bones. Other discoveries are more about how we think about dinosaurs. This is especially true of the first few chapters, which serve to illustrate how clueless early researchers were about certain things, while being pretty smart about other things.

Chapter 6, on Eoraptor, focuses not on a specific discovery, but rather, on the question of what a dinosaur actually is, how taxonomy has changed, and on attempts to identify and define the basal dinosaur (which is not Eoraptor, but it kinda is). There are other similar orienting pauses elsewhere in the book as well.

Although the chapters vary a great deal in the range of time, space, or fossil material covered, they follow a general pattern of putting together in one place most of the pertinent facts about a particular episode in the history of dinosaur research, and the pertinent facts about a particular part of the overall dinosaur bestiary. All in all, there is a good bit of history, history of the science, anatomy, evolutionary biology, scientific drama, greatness and tragedy of the act of discovory (or loss), and many many bones.

It is important for you to know that Prothero brings the reader up to date on many, probably most, of the current dinosaur controversies and conundra. The Story of the Dinosaurs in 25 Discoveries: Amazing Fossils and the People Who Found Them is divided into four sections. The first is about early finds and early thinking, from the dark ages of dinosaur research. The second focuses on the long-necked giants, the third on theropods, and the fourth on the ornithischians (duck beaked, horned, and spiky armored dinosaurs). I’ve put a current draft of the TOC at the bottom of the post to give you an idea of the detail of coverage.

I highly recommend this book.

Also by Prothero: When Humans Nearly Vanished: The Catastrophic Explosion of the Toba Volcano, Reality Check: How Science Deniers Threaten Our Future, UFOs, Chemtrails, and Aliens: What Science Says, The Princeton Field Guide to Prehistoric Mammals (Princeton Field Guides), California’s Amazing Geology, and coming out in the future: Fantastic Fossils: A Guide to Finding and Identifying Prehistoric Life, and a bunch of other books.

TOC:
Part I. In the Beginning
1. Megalosaurus: The “Great Lizard,” the “Scrotum Humanum”, and the First Named Dinosaur
2. Iguanodon: Gideon Mantell, Louis Dollo, and the First Dinosaur Fauna
3. Cetiosaurus: The “Whale Lizard,” Richard Owen, and the First Known Sauropod
4. Hadrosaurus: Joseph Leidy and the First American Dinosaur
5. Eoraptor: The First Dinosaurs
Part II. The Long-Necked Giants
6. Plateosaurus: Ancestors of the Giants
7. Apatosaurus and Brontosaurus: Marsh, Cope, and the Bone Wars
8. Diplodocus: The Real “Jurassic Park” and Carnegie’s Gift
9. Giraffatitan: The Tallest of the Tall, and the Tendaguru
10. Patagotitan: Who’s the Biggest of Them All?
Part III. Red in Tooth and Claw: The Theropods
11. Coelophysis: The Little Dinosaur of Ghost Ranch
12. Cryolophosaurus: Denizen of the Polar Darkness
13. Spinosaurus: Lost Giants of Egypt
14. Tyrannosaurus: King of the Tyrant Reptiles
15. Giganotosaurus: Biggest Predator of All?
16. Deinocheirus: “Terrible Hands” Lead to Big Surprises
17. Velociraptor: “Terrible Claws” and the Dinosaur Renaissance
18. Sinosauropteryx: Feathered Dinosaurs and the Origin of Birds
Part IV. Horns and Spikes and Armor and Duck Beaks: The Ornithischians
19. Heterodontosaurus: The Origin of Ornithischians
20. Stegosaurus: The “Roofed Lizard” and the Thagomizer
21. Ankylosaurus: Armored Dinosaurs and “Mr. Bones”
22. Corythosaurus: Duckbills with Headgear
23. Stegoceras: The “Unicorn Dinosaur” and the Boneheads
24. Protoceratops: The Griffin Legend and the Origin of Horned Dinosaurs
25. Triceratops: The “Dinosaurian Bison” and the Last of the Dinosaurs

Scientists from the New Mexico Musum of Natural History, and the Archaeology Program of the Maryland National Capitcal Parks and Planning Commission (no, archaeologists normally do not look for dinosaurs) report the discovery of Crittenden krzyzanowskii, which means “critter that will bite your face off”*, in southeastern Arizona.

This newly discovered dinosaur was about 11 feet long, ate plants, and lived in a region of a large lake. By comparison, the more classically known Tricerotops ran between 25 and 30 feet in length.

This is seen as a new species, as is the case with this type of dinosaur, because of details of the “frill” part of the back of the skull. According to the researchers, the “parietosquamosal frill of C. krzyzanowskii had a broad medial ramus and at least five epiparietal loci situated around the margin …, a typical characteristic of Centrosaurinae. The epiparietals are pronounced triangles that are dorsally concave and ventrally convex.” And, as if that wasn’t enough, two large, triangular hook-like flanges, nearly the size of the epiparietal loci, are situated along the dorsomedial margin of the parietal ramus. The left squamosal has a pronounced dorsal ridge with a single dorsal squamosal process and large episquamosal undulations, a typical characteristic of Centrosaurinae.” I know, TMI.

In an important note on timing, the researchers also note that “the presence of C. krzyzanowskii in Arizona indicates that the nasutoceratopsins persisted into the late Campanian. The temporal and paleobiogeographic distribution of Nasutoceratopsini further weakens the hypothesis of distinct northern and southern Laramidian provinces.” I’m pretty sure I always thought this, and I’m happy to see it finally supported in the fossil record.

Full citation: Lucas, Spencer, Sebastian Dalman, Asher Lichting, and John-Paul Michael Hodnett. 2018. A new ceratopsid dinosaur (Centrosaurinae: Nasutoceratopsini) from the Fort Crittenden Formation, Upper Cretaceaus (Campanian) of Arizona. New Mexico Museum of Natural History and Science Bulletin 79. You can probably see the original paper HERE.

*Only joking. From the press release, “the name Crittendenceratops is for the Fort Crittenden Formation (the rock formation that yielded the dinosaur fossils) and Greek ceratops, which means horned face. The species name krzyzanowskii is for the late Stan Krzyzanowski, a NMMNHS Research Associate who discovered the bones of the new dinosaur.”

The word comes from the ancient Greek for “Fish Lizard.” One wonders what they were smoking.

But seriously, this category of creature is an entire order unto itself, part of the Reptile class. They first appear in the fossil record around 250 million years ago, and dwindled into extinction about 90 million years ago. There origin occurs at about the same time as the beginning of the Triassic, becoming diversified and abundant by the end of the triassica nd early Jurassic.

Very little is known about how the Ichthyosaur first evolved from a land-based reptilian stock. A separate group, called the Hupehsuchia, date to the very early Ichthyosaur times, and resemble them, but with distinct differences. Hupehsuchia did not last very long. It is likely that Hupehsuchia represent a link between an unknown pre-aquatic reptile and actual Ichthyosaurs, in indirectly, and arose from near the base of the Ichthyosaur linage. This is debated.

But never mind, for now, the early beginnings of the enigmatic fish lizard. Consider instead what it ended up becoming. Even early in their evolutionary history, Ichthyosaurs really do resemble modern day toothed whales, especially the dolphins and porpoises. Here are the skeletons of an Ichthyosaur and a Dolphin compared.

The differences are not small, but they relate more to the underlying skeletal patterns in reptiles vs mammals. For example, reptiles have a lot of vertebra and thus ribs, and the number seems to vary evolutionary across genera as needed, while mammal vertebrae and rib patterns are much more constrained. Also, those weird sclerotic plates in the eyes … these are eye bones found across vertebrates but not mammals (or crocodilians).

So, Ichthyosaurs are basically reptilian dolphins in overall appearance. It turns out they are dolphinesque in another important way as well, according to just published research.

In Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur by Yohan Lindgren, Peter Sjövall, Volker Thiel, Wenxia Zheng, Shosuke Ito, Kazumasa Wakamatsu, Rolf Hauff, Benjamin P. Kear, Anders Engdahl, Carl Alwmark, Mats E. Eriksson, Martin Jarenmark, Sven Sachs, Per E. Ahlberg, Federica Marone, Takeo Kuriyama, Ola Gustafsson, Per Malmberg, Aurélien Thomen, Irene Rodríguez-Meizoso, Per Uvdal, Makoto Ojika & Mary H. Schweitzer, we learn:

Here we show that this resemblance [to Dolphins] is more than skin deep. We apply a multidisciplinary experimental approach to characterize the cellular and molecular composition of integumental tissues in an exceptionally preserved specimen of the Early Jurassic ichthyosaur Stenopterygius. Our analyses recovered still-flexible remnants of the original scaleless skin, which comprises morphologically distinct epidermal and dermal layers. These are underlain by insulating blubber that would have augmented streamlining, buoyancy and homeothermy. Additionally, we identify endogenous proteinaceous and lipid constituents, together with keratinocytes and branched melanophores that contain eumelanin pigment. Distributional variation of melanophores across the body suggests countershading, possibly enhanced by physiological adjustments of colour to enable photoprotection, concealment and/or thermoregulation. Convergence of ichthyosaurs with extant marine amniotes thus extends to the ultrastructural and molecular levels, reflecting the omnipresent constraints of their shared adaptation to pelagic life.

So they may have been homeothermic (warm blooded, more or less). They may also have had countershading seen in today’s fishy and other swimmy things, with a lighter belly and darker flanks. This may have served as both camouflage and protection from UV light.

The paper was published in Nature.

George R. McGhee Jr.’s Carboniferous Giants and Mass Extinction: The Late Paleozoic Ice Age World is not light reading. It is an academic treatise delving into climate change and geology, and related evolution, of the Carboniferous period. The Carboniferous was about 60 million years long, followed the Devonian and preceded the Permian, and the name refers to the giant amounts of coal that apparently formed during this period. This was a warm period and a period with multiple ice ages. The time span covered in this book, which goes well more recent than just the Carboniferous, is plenty long enough for all the continents to travel great distances, and the basic configuration of the Earth to change. There were periods so warm that multi-cellular land life likely did not exist at all in the tropics. The arctic was covered with a continent and it was very warm and lush, even if dark for half the time.

This is probably the time for a book like this, since over the last decade or so a great deal of field research and laboratory analysis of isotopes and other invisible things has led us to the point where a comprehensive overview of great and deep time, globally, is possible without the use of truthy but overdone generalizations. You get the sense form McGhee’s book of significant variation across space and time that is understood at some level of detail. Paleontology turns time machine at a finer scale than usual. You also get a sense of the bigness of change that can happen in the ecological systems we have here on Earth. It is very big. Outright scary, in fact.

As noted, this is not a light and airy science book written by a skilled science writer. It is a deep dive written by an expert who has the rare capacity to put a vast array of information into perspective. The black and white illustrations are very well chose and executed and in some cases startling. I give this read a strong yes.

ABOUT THE AUTHOR
George R. McGhee Jr. is Distinguished Professor of Paleobiology at Rutgers University and a fellow of the Konrad Lorenz Institute for Evolution and Cognition Research in Klosterneuburg, Austria. He has held research positions at the University of Tubingen, the Field Museum of Natural History, and the American Museum of Natural History. His books include The Late Devonian Mass Extinction: The Frasnian/Famennian Crisis (1996); Theoretical Morphology: The Concept and Its Applications (1999); and When the Invasion of Land Failed: The Legacy of the Devonian Extinctions (2013), from Columbia University Press.

TOC:

Preface
1. Harbingers of the Late Paleozoic Ice Age
2. The Big Chill
3. The Late Carboniferous Ice World
4. Giants in the Earth . . .
5. The End of the Late Paleozoic Ice Age
6. The End of the Paleozoic World
7. The Legacy of the Late Paleozoic Ice Age
Notes
References
Index

These lizards are related to the mammal-like reptiles that are, in turn, ancestral to mammals.

The teeth show plant eating, and in particular, they show a morphology thought to be linked to a more specialized consumption of a higher quality, lower fiber diet. This is actually something I know something about, and for that reason, I’m going to reserve comment on this interpretation and its meaning until I’ve thought about it a bit more. But, we can probably take the researchers word for this at the moment. do have one provisional comments about the diet of Gordodon kraineri. It is small for a plant eating lizard, said from the teeth to be specialized in higher quality plant parts. For this reason, I wonder, is there any evidence of co-evolution between this lineage of specialist plant eaters and the plants they ate? There should be, might be hard to find, but probably worth looking for.

Abstract:

Gordodon kraineri is a new genus and species of edaphosaurid eupelycosaur known from an associated skull, lower jaw and incomplete postcranium found in the early Permian Bursum Formation of Otero County, New Mexico, USA. It has a specialized dental apparatus consisting of large, chisel-like incisors in the front of the jaws separated by a long diastema from relatively short rows of peg-like maxillary and dentary cheek teeth. The dorsal vertebrae of Gordodon have long neural spines that bear numerous, randomly arranged, small, thorn-like tubercles. The tubercles on long neural spines place Gordodon in the Edaphosauridae, and the dental apparatus and distinctive tubercles on the neural spines distinguish it from the other edaphosaurid genera—Edaphosaurus, Glaucosaurus, Lupeosaurus and Ianthasaurus. Gordodon is the oldest known tetrapod herbivore with a dentary diastema, extending the temporal range of that anatomical feature back 95 million years from the Late Triassic. The dental apparatus of Gordodon indicates significantly different modes of ingestion and intraoral transport of vegetable matter than took place in Edaphosaurus and thus represents a marked increase in disparity among edaphosaurids. There were two very early pathways to tetrapod herbivory in edaphosaurid evolution, one toward generalized browsing on high-fiber plant items (Edaphosaurus) and the other (Gordodon) toward more specialized browsing, at least some of it likely on higher nutrient, low fiber plant items. Gordodon shows a surprisingly early specialization of the dental apparatus and indicates how incomplete our knowledge is of edaphosaurid evolution, disparity and diversity.

Artist’s reconstruction of the new fossil find about to eat a plant, in a specialized manner:

The movie:

The original paper is available as an OpenAccess paper at Palaeontological Electronica.

Full Reference: Spencer G. Lucas, Larry F. Rinehart, and Matthew D. Celeskey. The oldest specialized tetrapod herbivore: A new eupelycosaur from the Permian of New Mexico, USA. Article number: 21.3.39

I cut my climate teeth on the Younger Dryas. I was studying under Glynn Isaac when a number of palaeoclimate related data and observations rather suddenly came together, and the likely relevance of Milankovitch orbital geometry emerged. This is the subtle and regular pattern of the way the Earth goes around the Sun, resulting in periods of time — thousands of years long — when the Summer Solstice (in Late June, these days) is also a time of year when the total amount of Sun’s energy falling on the Earth is at a periodic minimum. In other words, the potential for having a really cold summer is high. Or a few of them in a row. This in and of itself does not cause an Ice Age. It probably takes a handful of different things being true all at once for the planet to plunge into a cold phase, including the position of continents and mountains, behavior of sea currents, and atmospheric dust caused by large volcanic eruptions or meteor impacts. But during these Milankovitch set-ups, an Ice Age, or more properly termed, a glacial period, is reasonably likely all else being slightly colder than equal.

The periodic and orbit-determined nature of glacial periods was proven from work done during the 1960s, 1970s, and then assembled into something that made sense in the 1980s. Fort this to happen, oceanography had to be invented. Stable isotope chemistry had to develop. The ability to raise cores from the deep sea needed to develop, and then, a bunch of such cores had to be raised and studied. Then it all had to be put together. The key “moment” was the development of deep-time core sequences, first from deep sea sediments, then ice cores, covering over 100,000 years (and eventually, 800,000 years) of time, showing changes in the isotopic composition of sea water at a scale approaching year-to-year variation.

I got to see that happen, and I was enthralled, while being Glynn’s student. He knew all the coring and isotope people, and they were in and out of Isaac’s “Stone Age Lab.” Not long into this, however, Glynn died, and the Stone Age Lab was taken over by Ofer Bar-Yosef. Ofer was working on the origin of plant agriculture in the Near East, and was very interested in the fine tuned time scales provided by dipsy cores, er, deep sea cores. (Ofer’s Israeli accent confused many an undergrad. “I love this course, but he keeps showing all these ocean cores but he’s talking about dipsy this and dipsy that!!!”) These cores, with their detailed isotopic records, showed the coming and going of major ice ages very clearly.

The cores contain the remains of the tiny skeletal bits of microscopic organisms that made part of their hard parts using Oxygen from the sea in which they lived. Short lived organisms, they contributed on their deaths to the sediment at the bottom of the sea, leaving an ongoing record of that Oxygen’s isotopic makeup. Specifically, you can measure, with some fancy machines and some necessary and logical adjustments to the data, the ratio of heavier vs. lighter isotopes of Oxygen in the ocean at the time the organisms lived. Water made with the lighter oxygen literally jumps out of the ocean, in the process of evaporation, at a slightly higher rate than the heavy Oxygen based water.

Therefore, rainwater is isotopically light.

Therefore, glacial ice is isotopically light.

Therefore, when a lot of the Earth’s rainwater is trapped as glacial ice, the oceans are isotopically heavy.

Therefore the organisms that use that oxygen are isotopcialy heavy or light depending on global climate, and this signal is preserved in the dipsy, er, deep sea, cores.

And so, we were able to see the “Younger Dryas” pretty clearly.

But what is the Younger Dryas? What is a Dryas? And what ever happened to the Older Dryas?

A Dryas is a cold loving cute little flowering plant that is abundant enough, when it is abundant, to produce sufficient pollen that is readily identifiable as to be counted in ancient pollen records, taken from fresh water swamps and lakes and such.

There are two fairly recent periods when Dryas, always rare, peaks, in pollen profiles observed in the Middle East and parts of Europe. An older time (27K to 24K years ago) and a more recent time (12,900 to 11,700 years ago). The more recent time is the Younger Dryas. Since the plant shows up during cold periods, the Younger Dryas was considered to be a brief return of ice age conditions following the initial de-glaciation from the last major Ice Age.

People figured out that the Younger Dryas was actually visible in other places, not just where those pollen profiles showed up. In fact, everywhere where there is a record of ice age glacial activity that is sufficiently detailed, it is there. In North America, it is called the “Lexingtonian Readvance” because of a lobe of glacial ice re-grew near Lexington Massachusetts, indicating a rapid and short turn return to glacial conditions. Every major region glaciated at the end of the last Ice Age has these re-advance lobed, generally locally named. It is pretty clear that the Younger Dryas was global, and significant enough to leave a mark.

The Younger Dryas is absolutely clear in the ancient record of ocean Oxygen isotopes. It looks like this:

This is a portion of a graph you can see in Wikipedia. The squiggly lines represent Oxygen isotopes, but in ice rather than deep sea sediments. You can see a trend from lower (colder) to higher (warmer) that is followed by a long period of warm conditions (that’s us, now, on the far left). The arrow points to a clear reversal in the warming trend, showing this as the Younger Dryas.

Ofer Bar-Yosef has proposed that the Younger Dryas was linked to the origin of cereal agriculture in the Middle East. He was probably right. How did that work? People living in the Levant at the time were pretty successful foragers. They relied on a wide range of foods, including hunted gazelle and a range of plant products. But they were increasingly exploiting cereal grains, likely wild barley and wheat. Foraging was so successful that many settlements formed that became permanently occupied. People may have moved around a lot, but somebody was staying in these small villages year round.

As climate got better and better, over a period of just a few human generations, this pattern developed. But then the cold shift occurred. Bar-Yosef suggests that this was the trigger to increase exploitation of certain resources, shift away from some resources that became more rare, but mainly, to start or accelerate an ongoing process of tending the grains that were already being harvested. The morphological indicators that distinguish wild from domestic grain show up in various species of edible grasses starting at this time. Humans invent agriculture in the Middle East.

I hasten to add that humans invented agriculture (horticulture and/or animal husbandry) in many locations around the world, starting at or near the beginning of the warm period shown in the graph above. But the situation in the middle east was a bit different, probably earlier than all or most other cases, and very sudden owing to the invention, or as Bar-Yosef puts it, revolution, of agriculture.

So, the Younger Dryas, which you now know all about, was very impactful for humans, in a way you now also know about. But what about the reverse? Did impacts cause the Younger Dryas?

I ask this now because there are news stories everywhere (see this) about a giant crater found in Greenland, suggesting that this meteor strike caused the Younger Dryas.

A meteor impact could cause a cooling trend. If the meteor hit a major Greenland glacier, it could cause melt-water to alter sea currents, thus causing the Younger Dryas. Indeed, the idea of glacial melt-water associated with the simple melting of glaciers following an ice age was at one time thought to be sufficient to trigger a re-glaciation, short lived.

Unfortunately, the dating of this impact is very very iffy, and the chances of it having actually happened at the exact right time to be implicated with the Younger Dryas is approximately zero. Also, any melting of ice causing fresh water to alter Atlantic sea currents would possibly cause a climate shift like the Younger Dryas; there is evidence of melt water changing currents around that time; that evidence has already been examined closely and the timing of that event does not fit with the Younger Dryas.

So, no.

Mark Boslough, on Twitter, and Stefan Rahmstorf, in several publications, agree. Rahmstorf has documented a 1470 year period abrupt glacial event phenomenon, of which the Younger Dryas looks like just another one. During these glacial periods, either full on glacial events or as the planet is pulling out of or falling into one, there is a lot of wild swinging around of the climate. The Younger Dryas is probably just one of those swings, and may well be one that fits into a periodic schedule unrelated to meteors, as sexy as meteors are.

Expect more on this over the next few weeks. Keep an eye on RealClimate blog, I’ll bet they discuss it there.

From the abstract:

Over a decade ago, the Atacama humanoid skeleton (Ata) was discovered in the Atacama region of Chile. The Ata specimen carried a strange phenotype—6-in stature, fewer than expected ribs, elongated cranium, and accelerated bone age—leading to speculation that this was a preserved nonhuman primate, human fetus harboring genetic mutations, or even an extraterrestrial. We previously reported that it was human by DNA analysis with an estimated bone age of about 6–8 yr at the time of demise. To determine the possible genetic drivers of the observed morphology, DNA from the specimen was subjected to whole-genome sequencing using the Illumina HiSeq platform with an average 11.5× coverage of 101-bp, paired-end reads. In total, 3,356,569 single nucleotide variations (SNVs) were found as compared to the human reference genome, 518,365 insertions and deletions (indels), and 1047 structural variations (SVs) were detected. Here, we present the detailed whole-genome analysis showing that Ata is a female of human origin, likely of Chilean descent, and its genome harbors mutations in genes (COL1A1, COL2A1, KMT2D, FLNB, ATR, TRIP11, PCNT) previously linked with diseases of small stature, rib anomalies, cranial malformations, premature joint fusion, and osteochondrodysplasia (also known as skeletal dysplasia). Together, these findings provide a molecular characterization of Ata’s peculiar phenotype, which likely results from multiple known and novel putative gene mutations affecting bone development and ossification.

Figure 1 from the paper:

You will read here and there on the internet that this individual’s body was likely deposited within the last 50 years.

However, that “fact” is itself a deletion style mutation. Somewhere along the line a zero was deleted from the number “500” in the original report. While this mutation is not as interesting as the mutations that led to the odd development of this unfortunate person, it is fully ironic.

The original paper is open source, and available HERE, which is why I’m not spending a lot of time in this post explaining the details. You can read it yourself!

Also, there’s a movie from 2013.

Anyway, recent research suggests, controversially, that the early birds were not built to do this, and may have been too heavy.

Here’s the basis of this suggestion. Early birds had a pelvis that was fused, and thus, limited the size of the egg that could be produced. A smaller egg, with its thinner shell, would have been too weak to allow a bird large enough to produce that egg to sit on it without breaking it.

(There are no pertinent actual fossil eggs at this time.)

The controversy arises from the belief among dinosaur-ologists that some non bird dinosaurs were brooding their eggs at this time, so naturally, birds could have done this. However, if you think about it, maybe that assumption would not have emerged to begin with if this bird study was done fifty years earlier.

Here is the abstract:

Numerous new fossils have driven an interest in reproduction of early birds but direct evidence remains elusive. No Mesozoic avian eggs can be unambiguously assigned to a species, which hampers our understanding of the evolution of contact incubation, which is a defining feature of extant birds. Compared to living species eggs of Mesozoic birds are relatively small, but whether the eggs of Mesozoic birds could actually have borne the weight of a breeding adult has not yet been investigated. We estimated maximal egg breadth for a range of Mesozoic avian taxa from the width of the pelvic canal defined by the pubic symphysis. Known elongation ratios of Mesozoic bird eggs allowed us to predict egg mass and hence the load mass an egg could endure before cracking. These values were compared to the predicted body masses of the adult birds based on skeletal remains. Based on 21 fossil species, we show that for non?ornithothoracine birds body mass was 130% of the load mass of the eggs. For Enantiornithes body mass and egg load mass were comparable to extant birds, but some early Cretaceous ornithuromorphs were 110% heavier than their eggs could support. Our indirect approach provides the best evidence yet that early birds could not have sat on their eggs without running the risk of causing damage. We suggest that contact incubation evolved comparatively late in birds.

Deeming, D.C. G. Mayer. 2018. Pelvis morphology suggests that early Mesozoic birds were too heavy to contact incubate their eggs. Journal of Evolutionary Biology. 27 Feb 2018

A 245 million-year-old fossil horseshoe crab recently discovered in Idaho has been named Vaderlimulus because the animal’s shield head resembles the helmet worn by Darth Vader from the Star Wars film series. Paleontologists from the New Mexico Museum of Natural History and Science in Albuquerque (Allan J Lerner, Spencer G. Lucas) and the University of Colorado at Denver (Martin Lockley) just published a scientific article describing the extinct fossil horseshoe crab. Their findings were published in the latest issue of the German paleontological journal Neues Jahrbuch für Geologie und Paläontologie, which is the world’s oldest paleontological journal.

Vaderlimulus is the first North American fossil horseshoe crab from rocks of the Triassic Period. The Triassic was the first period of the Mesozoic Era (252 to 201 million years ago). Dinosaurs and mammals were just beginning their evolutionary development during the Triassic, but horseshoe crabs were already ancient by that time. Their fossil record dates back at least 470 million years ago, but fossils of horseshoe crabs are generally rare. When horseshoe crab fossils are found they are often new to science, as is the case with Vaderlimulus.

There are only four species of horseshoe crabs alive today, and their populations are decreasing. They are not true crabs but are more closely related to scorpions and spiders. Modern horseshoe crabs are often considered ‘living fossils’ due to having shown little apparent change in physical appearance over a vast period of geologic time.

“Vaderlimulus, however, has unusual body proportions that give it an odd appearance,” said lead author Allan J Lerner. This in part led the paleontological team to conclude that Vaderlimulus belonged to an extinct family, the Austrolimulidae. Members of this family were expanding their ecological range from marine into freshwater settings during the Triassic and often exhibit body modifications that provide them with a bizarre appearance by modern standards.