So, it's been a little under a year since I last posted on this blog (mostly because school and work exists), but I happen to be back at SVP this year and also just to happened to (again) make a big vast list of what I saw at the sessions and posters. Since I wrote so much content down I thought it should all go into my next blog post, and so that's what I'm doing. I'll report in on what happens the next two days as well so people can begin to dissect everything they can.
As with before, I did not take notes during the sessions that are currently under embargo or anti-tweet policy, and as such nothing on those talks will be mentioned. If you want to read the abstracts of all the talks though, feel free to check them out here. Also note that while I did try to edit up all the text below, most were written down in blurbs, as that's just my note-taking style.
Hope these posts are of interest to everyone that wasn't able to attend the meeting!
- Danto: Development in stem amniotes starts from the dorsal and ventral-most regions of the vertebrae, but in the basal most temnospondyls they start from paired ossification centers that grow together to form a disk. (Paper)
- Curry: Exaeretodon frenguellii shows all forms of lamellar, parallel, and fibrolamellar bone, suggesting all forms of slow, moderate, and a little bit of fast growth respectively. LAGs present.
- Curry: Scaphonyx sanjuanensis shows highly vascularized FL bone, fast growth, with a few transitions to slow-growing periods. Lacks secondary osteons. Proterochampsa is similar. LAGs present.
- Curry: Chanaresuchus shows parallel-lamellar-zonal bone, moderate to fast growth. No fibrolamellar bone. LAGs present.
- Curry: Sillosuchus, Saurosuchus, and Trialestes show densely vascularized bone that lack LAGs, suggests very fast growth. Similarly, Eoraptor shows highly vascularized FL bone with peripheral slowing and sparse secondary osteons, and Herrerasaurus, Sanjuansaurus, and Eodromaeus also have densely vascularized FL bone but lack any LAGs whatsoever.
- Curry: Fibrolamellar bone tissue (consistent with fast growth) appears to be basal to archosauria.
- Sander: Sauropods lack growth marks (LAGs) in their long bones until they reach far into sexual maturity, which makes them difficult to age. Very fast growth.
- Sander: Stegosaurs and ankylosaurs show very well-developed growth marks. Ankylosaurs have characteristic structural fibers in both their osteoderms and long bones, which is unique among dinosaurs. Stegosaurs appear to be the slowest-growing dinosaurs given their size.
- Sander: Ornithopods in general show moderately large medullary cavities with LAGs and hadrosaurs show heavy amounts of remodelling of bone. Ceratopsians are similar, but small taxa show little remodeling while big taxa show heavy remodeling.
- Sander: More analyses of dinosaur bone morphology and histology can help us to identify even bone fragments to the family level.
- Canoville: The distribution of medullary bone in birds is poorly understood. Analyses suggest that it is only sometimes preserved in the bones of the torso, but that the leg bones almost always contain it during pregnancy (however, see below).
- Canoville: NMNS-VPDINO-2002-0901is a 3D preserved oviraptorosaur pelvic region which shows two eggs in the pelvic cavity, showing it was a pregnant female that died in its 9th year. Melladulary bone was not detected in this specimen despite clearly being a pregnant female, but endosteal lamellar bone (which is present in the specimen) could be used as a sustitute indicator that it was once present.
- O'keefe: Specimen of what seems to be a Dolichorhynchops fetus’ flipper shows very fast intrauterine growth to 40% adult length at birth! (This is consistent with the Pregnant Poly Specimen at LANHM.) Adult bone is highly remodeled and doesn’t show this early developmental information..
- O'keefe: Dolichorhynchops long bones look a lot like penguin bones in overall shape morphology. Weird.
- Larsson: Mutant mice with an extra gene involved in limb development produce mutants with forelimbs similar to what’s seen in early stem tetrapodomorphs with extra digits, like Acanthostega. Mice with these mutations show extra sensory pads along the palm of the hand and well as extra nerve endings which can tell us important things about early tetrapod soft tissue.
- Sumida: Eudibamus cursoris shows further evidence for being the earliest known facultative biped. Comparison of the forelimb bones with other faculative bipeds shows similar proportions and morphology with early bipedal archosaurs, which appeared 40 million years later. Forelimb also shows a reduction of digits and a disparity between forelimb and hindlimb length characteristic of other bipedal groups, like theropods.
- Heers: The team used biomechanical modeling of Archeopteryx involving the entire torso and everything known about its anatomy, not just bits and pieces of it, to figure out how the animal flew/if it could fly. Using this information the authors were able to produce a digital model of Archeopteryx flapping and WAIR ability using both bird-like and crocodilian-like musculature.
- Heers: The models suggest a more pitched upright posture (rather than a horizontal posture) in flight might have been very important in early birds, as it allows for a greater range of motion in the forelimbs and greater flight strength in a pitched flight position than a horizontal one. The model also shows that the range of motion in early bird forelimbs isn’t as debilitating as would be expected, and that the pectoralis and supracoracoideus muscles might have been more limited by the orientation of the muscles than their size.
- Heers: Studies of modern bird chicks shows that juvenile birds require only about 10% the strength of an adult birds’ flight muscles to make it become airborne for quick burst flight. The pitched orientation and rapid flight stroke of early birds like Archeopteryx might have allowed for this quick burst to help reach high-up resources, climb, and escape predators.
- Haridy: Acrodont reptiles show clear evidence of tooth migration, with the jaw growing forward and the teeth being moved anteriorly in the jaws during growth. This also means that juvenile individuals have more tooth spaces than adults as the dentary increases in size. The taxa looked at went from 13 tooth spaces in juveniles to less than 10 tooth spaces in adults.
- Street: The types of mosasaur tooth ornamentation (faceted, fluted, striated, pebbled, serrated) is very fluid. A few ornamentations could be phylogenetically significant, but others could be more indicative of lifestyle.
- Street: Fluted and faceted teeth are very similar morphologically, but striated teeth have a much different enamel and dentine junction. Pebbled teeth (like seen in Globidens) have EXTREMELY thick enamel at the apex of the tooth (enamel makes up almost the entire top 2/3rds of the tooth). Finally, serrated mosasaurs teeth lack true dentin-core serrations like seen in theropods and varanid lizards, and shouldn’t be treated as serrated teeth. Better term would be crenulated.
- Brink: Heterodont dentitions can both appear in animal groups through ontogeny, or through evolution. Some lizards like tegus go from a monodont dentition to a heterodont dentition through ontogeny.
- Brink: Leopard geckos are born with two prominent egg teeth at the front of the jaw which are lost quickly after development to make room for a traditionally monodont dentition. How the jaws change through ontogeny to accommodate the loss of such large egg teeth are important to understanding the dental size variation in amniotes.
- Bramble: Tooth zones in hadrosaur jaws have surrounding zones of apposition and resorption which would move the position of the teeth as the animal grew.
- Bramble: Hadrosaur teeth migrated inwards and forwards as they grew, and the migration continued after they finished growing, likely to accommodate the forces with their oral food processing.
- Wang: Oviraptorosaurs and early birds experienced reduction in tooth numbers through ontogeny. This loss seems to be tied with the development of the large rhamphotheca across the skull, and leads to the loss of the anteriormost teeth first.
- Carr: Tyrannosaur facial integumentary textures suggest keratinous sheets over the hornlets of the eyes and armored skin (scales or keratin?) over the front of the face and dentary. (Paper)
- Carr: I personally asked about the keratinous sheets which cover the face in crocodilians and "crack" in the embryo to form the "scales" of the adult. Carr says that it's impossible to tell at the moment the difference between true scales and a crocodilian-like keratinous sheet in tyrannosaurid skulls. Preserved tyrannosaur facial skin is the only way to answer the question.
- Button: Lots of uncertainties behind what exactly are the osteological correlates of rhampotheca in birds and non-avian dinosaurs. However, the number of pores on bird beaks seems to suggest it might scale with the thickness of the keratin on the beak. Birds with thin keratin have way fewer pores/foramina than birds with thick beaks (shoebill in their diagram was off the scale with how many pores and how thick the beak keratin was)
- Button: Erlikosaurus has extremely large foramina pits that puts it off the scale as an outlier when put on a graph. This high number of pores might be due to missidentification of ISOs among the foramina like seen in other theropods, birds, and crocodilians.
- Button: Oviraptorosaurs plotted normally in the high end of birds, possessing large numbers of foramina. This suggests thick and reinforced beaks for at least the taxa studied, if not the whole group.
- Bhullar: The evolution of key traits in bird beaks coincide with the development of traits in the brain associated with beak mapping in birds, which allows for tactile beak manipulation behaviors. This suggests that the bird beak evolved specifically to act like a "hand" for manipulating objects, much how we use our hands to manipulate objects (or type long blog posts).
- Romano: Milosaurus mccordi represents the largest known Carboniferous synapsid, estimated to be around 41kg based on limb and skeletal element data. It is crucial for understanding the early evolution of gigantism in terrestrial tetrapod communities.
- ?????: Diving depth preference and visual sensitivity in mosasaurs is poorly known, which is required to understand their habitat and foraging preferences. Studies of 3D well-preserved sclerotic rings in mosasaurs compared to what’s known of modern diving animals could give us ideas on at what depths different species of mosasaurs were foraging at. Ongoing research.
- ?????: New specimen of a tanystropheid from the Moenkopi formation shows that long-necked Tanystropheus-like members of the group inhabited both the Eastern and Western sides of Pangea at the same time. Further shows that the group was a widespread evolutionary success for roughly 35 million years.
- ?????: Specimen of a large (erythrosuchid?) archosauromorph maxilla from New Mexico in rocks less than 7 million years after the Permian-Triassic extinction event suggests that archosaurian faunas recovered much more quickly than initially believed. This suggests that the blank time period in the early Triassic fossil record is due to incomplete sampling rather than actual recovery rates. Trackways from large archosaurian reptiles in Arizona further suggest a fast recovery.
- Rosenbach: Probable new specimen of a giant azhdarchid, probably Ambourgiania philadelphiae, from the Muwaqqar formation, including elements never-before-seen in giant pterosaurs. New material includes a large chunk of the forelimb girdle and the distal portion of the upper and lower jaw (both were 49 cm long). Gives new implications for the body shape and proportions of this taxa.
- Garcia: Extreme tooth enlargement described in a new specimen of a rhabodontid from the Aix-en-Pronvince Basin in France. Well-preserved oral morphology of this new specimen shows that rhabodontids had extremely tall blade-like slicing teeth in the jaw forming a self-sharpening jagged edge along the tooth row. This morphology is suggested to have evolved to help chop up and consume soft monocot plants, which are common in the late Cretaceous of Europe. This is clearly different from the flattened grinding dentition in hadrosaurs, which likely evolved tooth batteries to better process conifers and tougher plants.
- Khansubha: New giant early Cretaceous titanosaur specimen from Thailand’s Khok Kraut formation. Possesses a well-preserved right humerus about 1.78 meters long and provides new information about giant titanosaurs from the northern hemisphere continents. Specimen was found associated with 7 shred teeth from allosauroid and spinosaurid dinosaurs thought to be shed from feeding, as well as crocodylomorph and hybont shark teeth from the same layer.
- Struble: Proximal shortening of phalanges is associated with specific ecology in birds, which has implications for early bird and paravian theropod behavior.
- Struble: Most ceolurosaurs and and early birds (Deinonychus, Compsognathus, Sinornithosaurus, Microraptor, Anchiornis, Iteravis, Zhongjianornis, and Pisciovoravis) all group with ground birds. However, other taxa tested (like Confuciornis) group heavily with perching birds.
- Hall: Hindlimb feathers are common in modern birds, but none are like the hindlimb feathers of paravians and early birds, and are symmetrical.
- Hall: A thermoregulatory role has been suggested for the feathers on the legs of modern birds. Evidence for this is very poor: no differences between taxa living in stable temperature environments and those in extreme temperature ones.
- Hall: The closest thing to early bird feathers are chicken breeds with a genetic mutation called “vulture hock,” which produces extremely long feathers off the legs which are sometime asymmetrical like what’s seen in Microraptor. Further studies of these breeds might provide some answers for what the leg feathers of early birds were for.
- Ksepka: New analyses and character traits from Madrynornis suggest it to be a sister taxa to Sphenicus and Eudiptula and a member of crown penguins. Makes it the earliest known crown penguin.
- Ksepka:Models of Madrynornis’ jaw musculature and beak form is consistent with fish-eating, rather than krill or shrimp-eating. Also suggests that piscivory is the ancestral condition for crown penguins, with krill-feeding evolving twice independently in the clade.
- Ksepka: Human activity has affected penguin diets in the past. Many modern krill-eating penguins only switched to a krill-based diet shortly after a combination of whaling and over-fishing led to an explosion in the krill populations.
- Faux: Different developmental processes in ratite embryological growth supports the idea of multiple independent loss of flight in different paleognath groups.
- Stidham: Ostrich eggshell and bone material from across Europe, Asia, North Africa, and India are often all lumped together under Struthio asiaticus, despite all being from dramatically different formations, environments, and time periods. This does not seem likely.
- Stidham: New material from the late Miocene Hezheng formation, including a good specimen which includes the first fossil ostrich skull and wing bones (as well as some fossilized trachea rings!) shows that the Hezheng species has slightly more gracile wing bones than modern ostriches. Despite this, it’s overall slightly larger than extant ostriches due to overall robustness.
- Stidham: The Hezheng specimens are noticeably different from European material, but it’s hard to tell differences between Struthio wimani and this taxa. All material appears much different from the Indian material, including the Stuthio asiaticus holotype.
- Stidham: Bite marks from mammalian carnivores on lots of the Hezheng ostirches: they were scavenged and predated on a lot.
- Stidham: New specimen with a skull and wings preserved also has a new large species of fossil mustelid preserved right next to the new complete Hezheng specimen in the same block.
- Musser: New morphological and genetic information of higher land birds has found a novel relationship for Aptornis: it is a gruoid and sister taxa to Psophia. The two share 13 significant morphological characters bringing them together.
- Musser: This is odd because much like the Sunbittern + Kagu and Tinamou + Moa clades suggested by recent phylogenies, Aptornis and Psophia are separated by vast oceanic distances, and one taxon is flightless and the other is a weak flier.
????? = Add-in posters not in the abstract book. I apologize to anyone who's posters was mentioned, let me know and I will make the correction.
And with that, I'll leave you with this pictures of a bunch of paleontologists on a seesaw, because that's how we roll at SVP 2017. See you tomorrow!
And with that, I'll leave you with this pictures of a bunch of paleontologists on a seesaw, because that's how we roll at SVP 2017. See you tomorrow!