Category Archives: Dinosaurs

Too Many Dinosaurs?

Dinosaurs were extremely successful, dominating Earth for millions of years (not even counting the many more millions of years that birds have flourished), in many and glorious variants.  But we have only sketchy notions of the growth and spread of these wondrous animals.  Fossil evidence is sparse and irregular, as is geological evidence of ancient environments, so simple tabulation offers limited information about the origins and spread over time of dinosaurs.

A new study approaches this problem with a Bayesian model to infer dispersion paths for different dinosaur taxa [2].  Using recorded finds for over 600 species, they project probable geographic locations through time, constructing a “path” representing the dispersion of the species.   The model also incorporates some factors such as diet and gait, though these factors have little impact at this granularity (i.e., walking speed means little over many thousands of years).

The results show a rapid geographical dispersal (beginning in present day South America), which slowed over time.  This is consistent with the notion that dinosaurs spread out into relatively unoccupied geographical areas, until eventually they filled the globe.

The researchers tie this pattern to the rate of speciation, which follows a similar trend. This is consistent with speciation due to invasion of new and geographically isolated environments.  In contrast, later times would presumably be dominated more by sympatric speciation, i.e., competition within a (crowded) system.

Early dinosaurs moved and speciated rapidly, with both processes slowing through time.”  ([2], p. 4)

The researchers characterize this pattern as a “geographical signature of an evolutionary radiation”.  The suggest that this offers explanatory hypotheses for phenomena such as the diversity of Hadrosaur cranial decorations thought to be due to sexual selection, which would be a likely mechanism for sympatric speciation.

They also perceive the slowing rate of speciation in the Cretatceous as evidence that the radiation was ending, and the dinosaurs were in decline [1].

But by the time the asteroid struck, killing them off, they were starting to decline, as they had ran [sic] out of space on Earth.”

My own view is rather skeptical, if only because the statistics are based on such paltry data.  There were millions and millions of dinosaurs, many of them tiny, and most probably unknown in the fossil record.  For those we do have evidence for, the species identification is quite uncertain, as is the presumed taxonomic tree and behavior. However clever the model, it is based on extremely weak data.

In any case, the relationship between supposed movement and the rate of speciation is almost a tautology.  I mean, what else could possibly happen over such long time periods?  And how could these not be correlated in such a limited dataset?

I’m certainly not convinced that dinosaurs were in decline, whatever that means. Even if the rate of speciation was slowing (which I don’t think is evident), that doesn’t mean they are disappearing (which they weren’t). I suspect that if we had more evidence, we might find lots of interesting adaptation happening in the Cretaceous, though possibly not easy to see in the skeletal remains.

On a side note, I note that the BBC headline suggests that the finding is that “Dinosaurs ‘too successful for their own good’”. The actual paper doesn’t really say that, and, as far as I can tell, no one ever said that specific quote.


  1. Helen Briggs, Dinosaurs ‘too successful for their own good’, in BBC News – Science & Environment. 2018. http://www.bbc.com/news/science-environment-42945820
  2. Ciara O’Donovan, Andrew Meade, and Chris Venditti, Dinosaurs reveal the geographical signature of an evolutionary radiation. Nature Ecology & Evolution, 2018/02/05 2018. https://doi.org/10.1038/s41559-017-0454-6

 

 

Dinosaur Footprints At Goddard SFC

In my lifetime, we have learned more about dinosaurs than in all history. Even more, we have learned that we can learn more than we thought.

When I was a young dinosaur fan, we were taught that all we knew about dinosaurs was fossilized skeletons, and this was probably all we every would know.  Since that time we have found many fossils that preserve impressions of skin and soft tissues, as well as fossilized tissues (e.g, this, this, this, this, this, this, this, this, this, this,). We have also found footprints. Many, many footprints [2].

The cool thing about tracks is that they tell us about the behavior of dinosaurs.  All the skeletons in the world tell us little about how dinosaurs moved, ate, and mated.

This month a team or researchers report on a remarkable find on the grounds of the NASA Goddard Spaceflight Center in Maryland: a slab of Cretaceous rock with dozens of animal tracks and other traces! [3]

As in so many cases, it was a lucky discovery.  Accidentally disturbed by construction, the fossil rich rock was fortunately located in a major nest of scientists. The significance was recognized on lunch break, and the remarkable find was excavated and preserved for study.  (Press reports indicate the deployment of ground penetrating radar—which the NASA boffins had close at hand, naturally—and a posse of volunteers—likely sporting a plethora of post-graduate degrees.)

In the twin bed sized area (2.4 x 1.0 meters) there are some 67 tracks, representing 40 trackways. Wow!

Photograph (A) and map (B) of replica GSFC-VP1 of whole track bearing surface. Note key to diversity of track morphotypes, and easily recognizable trackways of small theropods (in red), mammals (in blue) and pterosaurs (in green). The large discovery track, of inferred nodosaurian affinity, is situated beside small tracks also interpreted as nodosaurian. Track numbers corresponding to data are given in Supplementary Tables SI 1 and SI 2. See text for further details. All photographs and original map taken and compiled by the authors in Adobe Photoshop SC6. From [3].
The tracks include fairly large dinosaurs and smaller theropods.  There are small mammals and even pterosaurs.

These tracks suggest interesting stories about the life of these animals.  One trackway appears to be a nodosaur (this seems to be the week of the nodosaur), with tiny prints that could be a baby nodo beside mama or papa.  Other impressions are interpreted as beak marks where pterosaurs poked into the mud seeking food. Wow!

Even more impressive is the sheer number of species represented in this small space, presumably very close to the same time.

The small theropods are likely predators, so we are seeing evidence of what might be gangs of hunters after larger prey, pterosaurs on the ground, and perhaps an infant nodo.  Cool!

There are also mammal prints, which is unusual.  A lot of mammal prints.  Most of the mammal prints are difficult to interpret, but some appear to be sitting upright like squirrels. It is certainly a distinctive image, imagining Cretaceous proto-squirrel hopping along amid the large dinosaurs, pterosaurs, and toothy little theropod hunters.

There are also other traces, including chunks of armor and droppings.  Altogether, a slice of life from more than 60 million years ago.

Cool!


  1. Kenneth Chang, Where NASA Put a Parking Lot, Dinosaurs and Mammals Once Crossed Paths, in New York Times. 2018. p. A11. https://www.nytimes.com/2018/01/31/science/dinosaurs-footprints-nasa.html
  2. Martin Lockley, Tracking Dinosaurs: A New Look At An Ancient World, Cambridge, Cambridge University Press, 1991.
  3. Ray Stanford, Martin G. Lockley, Compton Tucker, Stephen Godfrey, and Sheila M. Stanford, A diverse mammal-dominated, footprint assemblage from wetland deposits in the Lower Cretaceous of Maryland. Scientific Reports, 8 (1):741, 2018/01/31 2018. https://doi.org/10.1038/s41598-017-18619-w

 

New African Dinosaur Reported

Dinosaurs have been found everywhere, and in recent years accompanying fossils have offered evidence of the ecology they lived in.  As more specimens accumulate, there is also more of a picture of the populations of dinosaurs, and relationships among populations around the world.

Still, the geography of millions of years ago is only partly understood, so it is uncertain where dinosaurs were isolated populations, and where they might overlap, compete, and interbreed with each other.

Surprisingly, one area of great uncertainly is the geography of Africa in early Cretaceous times.  With few fossils from that period known from present day North Africa and Middle East, little is known about the connections between dinosaurs in African and other land masses.

A new Titanosaur found in Egypt sheds light on this particular question [2]. The partial remains are some of the most complete ever found in the area.  One important point is that this is a perfectly ordinary (if small) Titanosaur, i.e., apparently not an isolated population.

The researchers at the Mansoura University Vertebrate Paleontology Center find that they are related to clades found in Southern Europe, but more distantly with farther south in Africa.  This indicates that there were routes between North Africa and Southern Europe at the time, and possibly less connection with the landmass to the south.

I note that the researchers (cautiously) criticize previous hypotheses that were based on “extremely limited and/or ambiguous evidence”. ([2], p. 6)   Quite.

It will be interesting to see if more remains can be found at this site, to help fill in this missing piece of the picture of the dinosaur world.


  1. Helen Briggs, Lost history of African dinosaurs revealed, in BBC News – Science & Environment. 2018. http://www.bbc.com/news/science-environment-42860263
  2. Hesham M. Sallam, Eric Gorscak, Patrick M. O’Connor, Iman A. El-Dawoudi, Sanaa El-Sayed, Sara Saber, Mahmoud A. Kora, Joseph J. W. Sertich, Erik R. Seiffert, and Matthew C. Lamanna, New Egyptian sauropod reveals Late Cretaceous dinosaur dispersal between Europe and Africa. Nature Ecology & Evolution, 2018/01/29 2018. https://doi.org/10.1038/s41559-017-0455-5

 

 

Old Stuff in 2017: Fossils, Earth History

This year there was a continuation of the flood of new fossil finds, especially from the fertile beds of Northwest China (though there are remarkable finds from all over).  Finds include new species of dinosaurs, and ever-increasing evidence about the close relationship between dinosaurs and birds.

Equally remarkable, there have been many discoveries of fossils preserving evidence of soft tissues and external appearance of ancient species.  When I was a dinosaur-mad lad, we were taught that it was impossible to ever know what dinosaurs looked like (or sounded like). But we now have hundreds of “impossible” fossils, with detailed remains of muscles, blood, skin, and, of course, feathers.

We also are learning more about the extinction of the dinosaurs, though there are still as many questions as answers.  There certainly was an impact event at Chicxulub, but it’s not clear how that played out, or how it caused extinctions.

In any case, it is now evident that whatever caused the death of so many species of dinosaurs, the event obviously did not wipe out the avian branch of dinosaurs, or frogs, or mammals.  Only some species ended at that time. Why?

The picture of other mass extinctions isn’t any clearer.

This research is important, because we are in the midst of a mass extinction, and the start of the Anthropocene age (which I’ve just decided to call “The Iceless Age”).  We can’t really stop it, nor can we really “work around” mass extinctions, rising seas, and the death of the oceans and forests.  But maybe we can understand what is happening, and what we have wrought.

Some Links

Dinosaurs

A Ducklike Dinosaur?
Pterosaur Eggs!
Dinosaur Feathers!
New Studies About The Chicxulub Asteroid Impact
Dinosaur Face Coloring and Camouflage
Book Review: “Weird Dinosaurs” by John Pickrell
Dinosaur Camouflage: Hiding From Hunters
How Fast was T. Rex?
Life After the Dinosaurs
Dinosaurs Rising From The Ashes
New Study: Tyrannosaurs Not Furry
Study Proposes New Family Tree For Dinosaurs
What A Dinosaur Looked Like
Dinosaur protein observed

Early Birds

Paleocene Penguin (very large!)
New Study of Mass Extinctions

Anthropocene

Antarctica Heat Flux Map
Antarctic Surface Under The Ice
Armadillos On The March!
The Ice is Melting
Where are the bees?
Antarctic Ice Losses

 

A Ducklike Dinosaur?

Dinosaurs occupied all of Earth, including the skies and waters.  Just as contemporary avian dinosaurs, ancient dinos evolved a plethora of bodies, specialized for different environments and ways of life.

This month, a team from Europe and Mongolia report on a new analysis of what appears to be a unique and weird looking aquatic dinosaur [1].  The particular specimen has an uncertain provenance, having been sold on the black market, and only recently examined by scientists [2].  Such a history screams “fake”, and the features of fossil are so unexpected that any reasonable person would assume it is phony.

However, careful examination with X-rays revealed that Halszkaraptor escuilliei is real, if unusual and, indeed mysterious. About the size of a Turkey, the specimen is clearly adapted for swimming – sort of.  Flipper like wings? Check.  Webbed feet? Nope?  Crocodile like snout? Check.

This is a reconstruction of Halszkaraptor escuilliei. The small dinosaur was a close relative of Velociraptor, but in both body shape and inferred lifestyle, it more closely recalls some water birds like modern swans. (Lukas Panzarin, with scientific supervision from Andrea Cau)

The paper offers an interesting diagram comparing the anatomy of Halszkaraptor to other animals. It seems to be partway between specialized swimmers and land animals. With only one specimen, and working only from the skeleton, it is difficult to know how to interpret this finding.

Morphometric analyses of aquatic adaptations in the Halszkaraptor forelimb. a, Binary plot of length ratios among manual digits I–III in aquatic and terrestrial sauropsids (n = 84): Halszkaraptor clusters with long-necked aquatic reptiles. b, Binary plot of principal components 2 and 3 from a morphometric analysis of ten skeletal characters of the forelimb and sternum in birds (n = 246; principal component 1 describes body size variation and is therefore not considered; see Supplementary Information): Halszkaraptor clusters with wing- propelled swimming birds. Silhouettes in a provided by D. Bonadonna and L. Panzarin.

 

This specimen is in the raptor family, which is the first aquatic raptor known. Indeed it is a rare swimming dinosaur.  Most of the dinosaur age sea life are not actually in the dinosaur family (they are related to turtles, et al.)

This study is a great example of how imaging technology is increasing the ability to understand fossil remains. Intensive but non-destructive examination made it possible to determine that this is not a fake, and to pull out details within the rock. Almost every paleontological report these days includes some form of “see through” imagery. This is a tremendous advance, and we can hope that methods will continue to improve.

(Many reports also include statistically constructed taxonomic trees, which I consider less of a boon. These family trees are as much art as science, and the visual appearance suggests far more certainty than is generally justified.)

Anyway, the dinosaur of the week is Halszkaraptor escuilliei!  (the designation “esculliel” honors the person who returned the fossil to Mongolia.)


  1. Andrea Cau, Vincent Beyrand, Dennis F. A. E. Voeten, Vincent Fernandez, Paul Tafforeau, Koen Stein, Rinchen Barsbold, Khishigjav Tsogtbaatar, Philip J. Currie, and Pascal Godefroit, Synchrotron scanning reveals amphibious ecomorphology in a new clade of bird-like dinosaurs. Nature, 12/06/online 2017. http://dx.doi.org/10.1038/nature24679
  2. Nicholas St. Fleur, This Duck-Like Dinosaur Could Swim. That Isn’t the Strangest Thing About it., in New York Times – Trilobites. 2017: New York. https://www.nytimes.com/2017/12/06/science/duck-dinosaur-swim.html

 

Pterosaur Eggs!

The flying dinosaurs are so cool! Monstrously large, yet fragile like so many contemporary birds. They must have been awesome in life!

But we know so little about them.

This fall a Chinese-Brazilian team reported a remarkable find of over 200 Pterosaur eggs [3]. Wow! (Up to now, there were only five complete pterosaur eggs known.)

The remains were excavated from the fabulously rich beds of Xinjiang in northwest China (where else!)

Some of the fossilized eggs are three dimensional, and some have remains of embryos, which could be examined with CT scans.

The researchers interpret the finds to be eggs that were washed away by storms, and subsequently filled with sand to become sandstone. The eggs and embryos were damaged and tossed about, and likely came from multiple nests.  So, unfortunately, this find doesn’t tell much about nesting behavior—though the large number of remains and eggs is consistent with gregarious nesting groups.

The researchers examined the embryonic remains, but it is difficult to estimate the age of embryos, especially without a complete record of development.  The authors speculate that the evidence hints that new borns could walk but not fly yet, and would need parental care.  This conclusion will need further data to support it.

Artist’s rendition of a family of pterosaurs, which had massive wingspans of up to 13 feet and likely ate fish with their large teeth-filled jaws. Illustrated by Zhao Chuang

  1. Helen Briggs, Fossilised eggs shed light on reign of pterosaurs, in BBC News – Science & Environment. 2017. http://www.bbc.com/news/science-environment-42177532
  2. Merrit Kennedy, Hundreds Of Eggs From Ancient Flying Reptile Are Found In China, in NPR News – Science. 2017. https://www.npr.org/sections/thetwo-way/2017/11/30/567225493/hundreds-of-eggs-from-ancient-flying-reptile-are-found-in-china?sc=tw
  3. Xiaolin Wang, Alexander W. A. Kellner, Shunxing Jiang, Xin Cheng, Qiang Wang, Yingxia Ma, Yahefujiang Paidoula, Taissa Rodrigues, He Chen, Juliana M. Sayão, Ning Li, Jialiang Zhang, Renan A. M. Bantim, Xi Meng, Xinjun Zhang, Rui Qiu, and Zhonghe Zhou, Egg accumulation with 3D embryos provides insight into the life history of a pterosaur. Science, 358 (6367):1197, 2017. http://science.sciencemag.org/content/358/6367/1197.abstract

 

Should one drink white or red wine with plesiosaurus, Herr Von Schoenvorts? ” From “The Land That Time Forgot” (1975)

 

Dinosaur Feathers!

And speaking of dinosaurs…

One of the enduring mysteries is just where feathers come from.

We now know that many genera of dinosaurs probably had feathers (but not T. rex), and obviously their avian  descendants are feathered.

It is generally believed that scales, hair, and feathers share the same evolutionary sources.  But how would scales evolve into anything resembling a feather?

This fall a team from China and the US report on experiments that show a biochemical mechanism that causes genes for “scales” to express proto-feather features [2].

Image caption Normal embryonic scales (L) compared with the elongated scales after genetic modification (R)

The details are rather complicated.  In fact, they identify five developmental steps in the development of a feather from a scale, controlled by several genes.

The general idea is that a series of biochemical changes in an embryo can induce the development of proto feathers.  From this beginning, different kinds of feathers would evolve under selection.

This new work helps to establish how feathers initially evolved, around 120 to 150 million years ago, but hints at five separate genetic processes active in birds that needed to work together to create modern feathers.

Is this the last word on dinosaur feathers?  I doubt it.  But it is a solid clue about how it might have worked.

This is a nice bit of work, and shows just how complicated development is. In my lifetime, sequencing genomes has become routine.  But working out how genes work is way, way harder than sequencing them.


  1. Rory Galloway, How dinosaur scales became bird feathers, in BBC News – Science & Environment. 2017. http://www.bbc.com/news/science-environment-42082489
  2. Ping Wu, Jie Yan, Yung-Chih Lai, Chen Siang Ng, Ang Li, Xueyuan Jiang, Ruth Elsey, Randall Widelitz, Ruchi Bajpai, Wen-Hsiung Li, and Cheng-Ming Chuong, Multiple regulatory modules are required for scale-to-feather conversion. Molecular Biology and Evolution:msx295-msx295, 2017. http://dx.doi.org/10.1093/molbev/msx295

 

 

PS.  Another great name for a band:  Dinosaur Feathers!