Baby Limusaurus had teeth!

This is pretty remarkable.
Wang et al. 2016 reported on a growth series for Limusaurus (Xu et al. 2009; Jurassic, Oxfordian; 1.7m in est. length; IVPP V 15923; Figs. 1-5,) “the only known reptile to lose its teeth and form a beak after birth.”  

You might remember
Limusaurus became famous earlier for its tiny forelimbs complete with a digit 0 medial to digit 1, that made theropod workers go bonkers because they assumed the digits present were 1-4, not 0-3.

Figure 2. Limusaurus also has four fingers and a scapula with a robust ventral area, like Majungasaurus, but those four fingers are not the same four fingers found in Majungasaurus.

Figure 1. Limusaurus also has four fingers and a scapula with a robust ventral area, like Majungasaurus, but those four fingers are not the same four fingers found in Majungasaurus.

Wang et al. report,
“The available data are important for understanding the evolution of the avian beak.” Except… Limusaurus is not close to the avian line of ancestry anyway you look at it. The LRT nests Limusaurus, with or without teeth, with Khaan, a toothless, beaked oviraptorid. Wang et al. nest Limusaurus with Elaphrosaurus (Fig. 3) even though Khaan is part of their taxon list. So something is not scored right. Not sure about the discrepancy, but some of that could be due to the misidentification of manual digits 0-3.

Figure 3. Khaan, an oviraptorid that nests with Limusaurus in the large reptile tree AND the repaired Cau, Brougham and Naish tree.

Figure 2. Khaan, an oviraptorid that nests with Limusaurus in the large reptile tree AND the repaired Cau, Brougham and Naish tree.

Wang et al. report,
“The ontogenetically variable features (e.g. teeth/no teeth, etc.) have little effect on its phylogenetic position.” The LRT agrees. Wang et al. report that no matter which ontogenetic stage is tested for Limusaurus, it always nests with or near the ceratosaur, Elaphrosaurus (Fig. 3).The LRT disagrees.  In other words, with or without teeth, the topology does not change. In the LRT  toothed juvenile Limusaurus also nested with Khaan. Toothed Juravenator and Sinosauropteryx nest as sisters to that clade. The large Compsognathus specimen CNJ79 (Fig. 6) was a basal taxon. All of these sisters are closer to Limusaurus in size and morphology than is Elaphrosauru (Fig. 3).

Figure 3. Elaphrosaurus is known from a partial skeleton lacking a skull.

Figure 3. Elaphrosaurus is known from a partial skeleton lacking a skull. Adult Limusaurus added to scale. Wang et al. consider these two to be sister taxa among basal theropods, which is not confirmed by the LRT.

The ontogenetic series of Limusaurus
is shown in figure 4. Not all the specimens are complete. None are shown to scale. All are portrayed as tiny rough tracings. I think this lack of detail is one shortcoming of the paper.

Figure 4. Specimens attributed to Limusaurus, not to scale.

Figure 4. Specimens attributed to Limusaurus, not to scale, from Wang et al. 2016.

Wang et al. also provided
reconstructions of a juvenile and adult Limusaurus (Fig. 5). Unfortunately, Wang et al. filled in all the missing bones and gave both reconstructions something of a generic theropod character, lacking some of the traits unique to this genus.

Limusaurus reconstructions from Wang et al. 2016, to scale and not to scale.

Figure 5. Limusaurus reconstructions from Wang et al. 2016, to scale and not to scale. The angle of the pubis is difficult to determine.

That Limusaurus juveniles had teeth
and adults did not, tells us less about the avian line and more about the oviraptorid line of theropod dinosaurs.

Figure 1. The large (from Peyer 2006) and small Compsognathus specimens to scale. Several different traits nest these next to one another, but at the bases of two sister clades. Note the differences in the forelimb and skull reconstructions here. There may be an external mandibular fenestra. Hard to tell with the medial view and shifting bones.

Figure 6. The large (from Peyer 2006) and small Compsognathus specimens to scale. Several different traits nest these next to one another, but at the bases of two sister clades. Note the differences in the forelimb and skull reconstructions here. There may be an external mandibular fenestra. Hard to tell with the medial view and shifting bones.

References
Wang S, Stiegler J, Amiot R, Xu W, Du G-H, Clark JM, Xu X 2016. Extreme ontogenetic changes in a ceratosaurian theropod. Currently Biology 27:1-5 plus SupData.

Full scale models from the vault

Back in the day
when I was writing and illustrating dinosaur books (1988~1992) I also built a few full scale models that I intended to use as subjects for paintings and museum displays. Here are most of them. Other models include the pterosaur skeletons you can see here.

Figure 1. Brachiosaurus skull, carved out of wood. Full scale.

Figure 1. Brachiosaurus skull, carved out of wood. Full scale.

At this point in my life
(1990s) the work (paintings / illustrations) was considered ‘acceptable.’ Even my papers were ‘acceptable.’ Unfortunately, when I started applying phylogenetic analysis to taxa and discovering new and overlooked relationships (published at ReptileEvolution.com, ) my work and manuscripts were no longer considered ‘acceptable,’ despite the fact that early discoveries made here are being re-discovered and validated years later by PhDs.

FIgure 2. Camarasaurus baby model. Full scale.

FIgure 2. Camarasaurus baby model. Full scale.

This Dimorphodon
(Fig. 3) was among the first of the models, based on Kevin Padian’s 1983 running illustrations.

Figure 3. Dimorphodon skull with dog hair for pycnofibers.

Figure 3. Dimorphodon skull with dog hair for pycnofibers.

Not sure why I produced this plesiosaur
because it took up a bunch of garage space and only entertained the mailman. Ultimately it was purchased by the AMNH, but never put on display. Where it is now is anyone’s guess.

Figure 4. Plesiosaur model. Full scale.

Figure 4. Plesiosaur model. Full scale. See figure 5 for the face.

Much of this plesiosaur
was fashioned at the late Bob Cassilly studios, who was a famous St. Louis sculptor and founder of The City Museum. Bob contacted me after seeing my book, Giants, because he had been commissioned to produce some of the giant marine animals pictured therein. Through that friendship in the 1990s, I was able to study specimens, including Sharovipteryx and Longisquama, from the traveling Russian Dinosaur Exposition that came to the City Museum for their first stop.

Figure 5. Plesiosaur model head detail. Full scale. Teeth are tree thorns.

Figure 5. Plesiosaur model head detail. Full scale. Teeth are tree thorns.

Among the smaller full scale models
is this sparrow-sized Pterodactylus in a bipedal pose (Fig. 6), ready to take flight.

FIgure 6. Pterodactylus scolopaciceps (n21) model. Full scale.

FIgure 6. Pterodactylus scolopaciceps (n21) model. Full scale. Later I learned that this genus was plantigrade (flat-footed), when quadrupedal. This one is about to take flight from a bipedal configuration. Digitigrady at this instance would have given Pterodactylus a bit more power in its initial leap during take-off.

And based on the evolution book

From the Beginning, these three (Fig. 7) are fleshed out steps in the evolution of tetrapods, cynodonts, mammals and man. Ichthyostega is a bit out of date now.

Figure 7. Ichthyostega, Osteolepis and Thrinaxodon, all more or less ancestral to humans. Full scale.

Figure 7. Ichthyostega, Osteolepis and Thrinaxodon, all more or less ancestral to humans. Full scale.

References
Padian K 1983. Osteology and functional morphology of Dimorphodon macronyx (Buckland) (Pterosauria: Rhamphorhynchoidea) based on new material in the Yale Peabody Museum, Postilla, 189: 1-44.

A Dinosaur Year 1989 Calendar

This ‘blast from the past’ by request: 
Click here or on image to download all 13 lorez images from my 1989 Dinosaur Year calendar, published by Alfred A. Knopf, New York. Thanks for the request, Leo!

I see two copies are presently available from Amazon.com here.

Click to download PDF of cover + 12 months of 1989 Dinosaur Year Calendar pix by David Peters at 72 dpi. It's over 25 years old and you'll find mistakes here. It was a product of its time.

Click to download PDF of cover + 12 months of 1989 Dinosaur Year Calendar pix by David Peters at 72 dpi. It’s over 25 years old and you’ll find mistakes here. It was a product of its time.

The calendar is over 25 years old
and you’ll find mistakes galore. It was a product of its time and the first time I ever painted dinosaurs in settings.

This followed
the book GIANTS and A Gallery of Dinosaurs, which illustrated dinosaurs on white backgrounds, all to the same scale. Both books are available as pdf files here and as used books at several online sites.

Where are the originals?
Collectors purchased all the originals except for the Brachiosaurus family in a pond (December) because it has a razor knife cut in the sky over the mountain top, inflicted upon opening the package at the publisher. It’s hanging on the wall over my monitor as I type this and I never notice the slit.

But wait! There’s more!
Click here to connect to a FREE build-it-yourself paper Pteranodon model.
And click here to connect to a FREE build-it-yourself paper Thalassomedon model.
All you need is 8.5×11″ bristol (stiff) paper, some glue or tape and a scissors or knife. Have fun, kids!

Feathered T-rex video: Excellent!*

The best video* I’ve seen on feathered dinosaurs.
*But note: their gliding Anchiornis forgot how to flap. Flapping came first. Then flapping with bipedal climbing. Then flapping with flying. Birds don’t come by gliding except to rest while airborne. Same with bats (if any glide ever). Same with pterosaurs. Let’s take gliding out of the equation for the origin of flight. That’s widespread antiquated thinking not supported by evidence. If you glide you do not flap. If you flap, some of your ancestors may learn to glide.

Click here or on the image to play.

Hypsibema missouriensis – a Late Cretaceous Appalachia duckbill dinosaur

Figure 1. Model of Hypsibema missouriensis, a hadrosaurid dinosaur

Figure 1. Model of Hypsibema missouriensis, a hadrosaurid dinosaur

Hypsibema missouriensis
(Cope 1869; Gilbert and Stewart 1945; Gilbert 1945; Baird and Horner 1979; Darrough et al. 2005; Parris 2006; Campanian, 84-71 mya, Late Cretaceous) is a fairly large hadrosaurid dinosaur discovered in 1942, at what later became known as the Chronister Dinosaur Site near Glen Allen, Missouri. At present this literal pinprick in the map of Missouri is the only site that preserves dinosaur bones.

Figure 2. Where the Hypsibema maxilla chunk came from on the skull of Saurolophus.

Figure 2. Where the Hypsibema maxilla chunk (Figure 3) came from modeled on the skull of Saurolophus.

Small pieces of broken bone and associated caudals and toes
were first discovered when digging a cistern. They had been found about 8 feet (2.4 m) deep imbedded in a black plastic clay. The area is in paleokarst located along downdropped fault grabens over Ordovician carbonates.

Gilmore and Stewart 1945 described a series of Chronister caudal centra (now at the Smithsonian) as sauropod-like, reporting, “The more elongate centra of the Chronister specimen, with the possible exception of Hypsibema crassicauda Cope, and the presence of chevron facets only on the posterior end appear sufficient to show that these vertebral centra do not pertain to a member of the Hadrosauridae.”

First named Neosaurus missouriensis,
the caudals were renamed Parrosaurus missouriensis by Gilmore and Stewart 1945 because “Neosaurus” was preoccupied. The specimen was allied to Hypsibema by Baird and Horner 1979.

Figure 3. Back portion of a Hypsibema maxilla showing tooth root grooves and cheek indention close to jugal.

Figure 3. Back portion of a Hypsibema maxilla showing tooth root grooves and cheek indention close to jugal.

Back in the 1980s
I enjoyed going to the Chronister site with other members of the local fossil club, the Eastern Missouri Society for Paleontoogy. I was lucky enough to find both a maxilla fragment (Fig. 3) and a dromaeosaurid tooth. I remember the horse flies were pesky and  one morning, before the other members got there, I was met by a man with a shot gun who relaxed when I identified myself. A friend found a series of hadrosaur toe bones, each about as big as a man’s hand (sans fingers). The bone was so well preserved you could blow air through the porous surfaces.

References
Baird D and Horner JR 1979. Cretaceous dinosaurs of North Carolina. Brimleyana 2: 1-28.
Cope  ED 1869.
Remarks on Eschrichtius polyporusHypsibema crassicaudaHadrosaurus tripos, and Polydectes biturgidus“. Proceedings of the Academy of Natural Sciences of Philadelphia 21:191-192.
Darrough G; Fix M; Parris D and Granstaff B 2005.
 Journal of Vertebrate Paleontology 25 (3): 49A–50A.
Gilmore CW and Stewart DR 1945. A New Sauropod Dinosaur from the Upper Cretaceous of Missouri. Journal of Paleontology (Society for Sedimentary Geology 19(1): 23–29.
Gilmore CW 1945. Parrosaurus, N. Name, Replacing Neosaurus Gilmore, 1945. Journal of Paleontology (Society for Sedimentary Geology 19 (5): 540.
Parris D. 2006. New Information on the Cretaceous of Missouri. online

wiki/Hypsibema_missouriensis
bolinger county museum of natural history
More info and links

They’re out there somewhere!

Back in the ’90s, 
I built several full scale prehistoric reptile models out of wood, wire, foam, glass (eyes) and what have you. Two of them are shown here (Fig. 1).

Figure 1. Baby Camarasaurus and featherless Deinonychus models built by David Peters in the 1990s.

Figure 1. Baby Camarasaurus and featherless Deinonychus models built by David Peters in the 1990s.

At the time, 
like the the extinct Steve Czerkas and the extant Charlie McGrady, I wanted to be build dinosaurs, not just illustrate them in books. At the time, St. Louis did not have a Science Museum and that’s when (so I was told) you are supposed to get in on the ground floor. Also at the time the late sculptor Bob Cassilly was building squids, pterosaurs, sharks and rays for the St. Louis Zoo based on illustrations in my book Giants. (Bob was instrumental in bringing Sharovipteryx, Longisquama and the other Russian dinosaur exhibit to St. Louis.) Alas, that phase fizzled and the writing of papers followed. Early on you’re driven by enthusiasm and reined in by naiveté. In evolutionary terms, it worked out for that time and place.

Along with
the baby Camarasaurus and adult Deinonychus, I built a plesiosaur, Tanystropheus, fuzzy Dimorphodon, Pterodactylus and the several pterosaur skeletons seen here. The fleshed out sculptures went to the AMNH in NYC. The baby sauropod went to Martin Lockley in Colorado. The skeletons all went to Mike Triebold. Many artists want to see their art hanging in museums. Well, it happened to me, sort of, with those pterosaur skeletons. They’re out there, all over the world. The AMNH ultimately decided to display only skeletons in their renovated prehistoric displays and sold off what they had purchased.

I have no idea
where the various pieces are now or what shape they are in. But it was fun for awhile and the mailman probably told his kids about the address that had dinosaurs under the carport. Now a longer list of illustrated and animated prehistoric reptiles can be found on the Internet here.

Lagerpeton: not the first of its kind, but the last of its kind

Quick note
I updated the reconstruction and nesting of Colobomycter, which you can see here.

Traditional paleontologists
consider Lagerpeton (Fig. 1, Romer 1971) a basal dinosauromorph, thus the first of its kind (ancestral to dinosaurs).

In contrast
Lagerpeton nests as a terminal taxon in the large reptile tree, leaving no known descendants. Here (Fig. 1) convergent evolution has created a bipedal chanaresuchid, derived from Tropidosuchus that has similar pedal proportions to the second specimen attributed to Tropidosuchus.

Figure 3. The closest kin of Tropidosuchus are the much larger Chanaresuchus (matching Nesbitt 2011) and the smaller Lagerpeton.

Figure 1. The closest kin of Tropidosuchus are the much larger Chanaresuchus (matching Nesbitt 2011) and the smaller Lagerpeton.

According to
Wikipedia, seven fossil specimens have so far been attributed to L. chanarensis. They don’t add up to much more than a hind limb and pelvic girdle.

  1. UPLR 06 (holotype) – articulated right hindlimb
  2. PVL 4619 – articulated pelvis with sacrum, partial right and complete left hindlimbs
  3. PVL 4625 – left pelvis with left femur and articulated vertebral column (dorsal, sacral and anterior caudal vertebrae
  4. PVL 5000 – proximal end of left femur
  5. MCZ 4121 – complete left, and partial right, femur.

Brusatte et al.
found Early Triassic footprints they attributed to lagosuchids. In reality the ichnites were closer to Rotodactylus tracks, which match the feet of fenestrasaurs, like Cosesaurus through pterosaurs.

In the large reptile tree
archosauriformes split at their origin, shortly after Youngina (AMNH 5561) and Youngoides (UC 1528) into two clades. The larger specimens start with Proterosuchus and radiate into choristoderes, parasuchians, doswellians and chanaresuchians terminating with Lagerpeton and its sister, Tropidosuchus (Fig. 1). The other branch starts with Euparkeria and extends to crocs, dinos and birds.

So,
Lagerpeton is not a close relative of dinosaurs, but convergent in several regards. The odd feet and pelves give them away as distinctly different from dinosaurs. Even so paleontologists continue clinging to this hypothesis. Better dino ancestors can be found here.

References
Arcucci A 1986. New materials and reinterpretation of Lagerpeton chanarensis Romer (Thecodontia, Lagerpetonidae nov.) from the Middle Triassic of La Rioja, Argentina. Ameghiniana 23(3-4):233-242. online pdf
Brusatte SL, Niedźwiedzki G, Butler RJ 2011. “Footprints pull origin and diversification of dinosaur stem lineage deep into Early Triassic.”Proceedings of the Royal Society B: Biological Sciences 278 (1708): 1107–1113. doi:10.1098/rspb.2010.1746PMC 3049033PMID 20926435.
Romer AS 1971 The Chanares (Argentina) Triassic reptile fauna X. Two new but incompletely known long-limbed pseudosuchians: Brevoria, n. 378, p. 1-10.
Sereno PC and Arcucci AB 1993. Dinosaurian precursors from the Middle Triassic of Argentina: Lagerpeton chanarensis. Journal of Vertebrate Paleontology, 13, 385–399.

wiki/Lagerpeton