WFS News: Tiny tyrannosaur fossil discovery changes the dinosaur timeline

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Tyrannosaurus rex wasn’t always the king of the dinosaurs. Before they became towering predators, tyrannosaurs started out much smaller, and a newly discovered fossil is helping fill the gap between those two extremes.

The fossil findings are detailed in a study published Thursday in Communications Biology.
The dinosaur fossil was found in Utah, where it lived 96 million years ago in a lush delta during the Cretaceous period. It’s been named Moros intrepidus, which means “harbinger of doom.” The dinosaur lived at the end of the allosaurs’ reign at the top of the food chain and before Tyrannosaurus rex arrived.
It’s now the oldest tyrannosaur from the Cretaceous period found in North America.
Medium-size tyrannosaur fossils have been found from the Jurassic period, about 150 million years ago. And then, about 81 million years ago during the Cretaceous, tyrannosaurs grew into giant predators and replaced allosaurs as the top of the food chain.
So what happened in between? Moros is helping researchers fill that 70 million-year gap, as well as provide a portrait of tyrannosaur lineage in North America. Moros links the earliest, smaller tyrannosaurs to Tyrannosaurus rex.
“With a lethal combination of bone-crunching bite forces, stereoscopic vision, rapid growth rates, and colossal size, tyrant dinosaurs reigned uncontested for 15 million years leading up to the end-Cretaceous extinction — but it wasn’t always that way,” said Lindsay Zanno, lead study author and paleontologist at North Carolina State University, in a statement. “When and how quickly tyrannosaurs went from wallflower to prom king has been vexing paleontologists for a long time. The only way to attack this problem was to get out there and find more data on these rare animals.”
Zanno and her team spent a decade searching for fossils from the Late Cretaceous period. They recovered teeth and a hind limb consisting of a femur, a tibia and parts of a foot belonging to Moros in the same area where Zanno found the fossil of a giant carnivorous carcharodontosaur.
But Moros stood between 3 and 4 feet tall. The dinosaur they found was 7 years old when it died, a nearly full-grown adult that would have weighed around 172 pounds. The elongated leg and foot bones indicated that it would be a great runner.
“Moros was lightweight and exceptionally fast,” Zanno said. “These adaptations, together with advanced sensory capabilities, are the mark of a formidable predator. It could easily have run down prey, while avoiding confrontation with the top predators of the day.”
This allowed Moros to be a survivor as the environment shifted and changed. For 15 million years, tyrannosaurs were restricted to this smaller size before evolving into giants (about 12 feet tall and 11,000 to 15,500 pounds) over a 16 million-year period.
“Although the earliest Cretaceous tyrannosaurs were small, their predatory specializations meant that they were primed to take advantage of new opportunities when warming temperatures, rising sea-level and shrinking ranges restructured ecosystems at the beginning of the Late Cretaceous,” Zanno said. “We now know it took them less than 15 million years to rise to power.”
Moros is most closely related to tyrannosaurs from Asia, which helped the researchers trace the dinosaurs’ lineage. This means Moros crossed the Alaskan land bridge during the Early Cretaceous to reach North America.
“T. rex and its famous contemporaries such as Triceratops may be among our most beloved cultural icons, but we owe their existence to their intrepid ancestors who migrated here from Asia at least 30 million years prior,” Zanno said. “Moros signals the establishment of the iconic Late Cretaceous ecosystems of North America.”
Source: Article By Ashley Strickland, CNN
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WFS News: 2.1-Billion-Year-Old Fossil May Be Evidence of Earliest Moving Life-Form

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About 2.1 billion years ago, a blob-like creature inched along on an early Earth. As the organism moved, it carved out tunnels, which may be the earliest evidence of a moving critter on the planet.

Until this discovery, the earliest evidence of motility — that is, an organism’s ability to move independently using its own metabolic energy — dated to about 570 million years ago, according to fossils from different locations. That’s a good 1.5 billion years younger than the new finding.

Whatever left the teeny, tiny tunnels was likely a cluster of single cells that joined ranks to form a slug-like multicellular organism, the researchers said. And perhaps, this sluggy conglomerate tunneled through the mud in search of greener pastures or food to gobble up, the international team of scientists said. [In Images: The Oldest Fossils on Earth]

However, not everyone agrees that these tunnels were made by complex life, and one researcher, who was not affiliated with the study, called the claims “imprecise.”

The researchers found the trace fossils in Gabon, along Africa’s west coast. A trace fossil is a fossil that was not part of an organism’s body that it leaves behind, such as a footprint, a burrow or even poop. In this case, the trace fossils are a series of slender tunnels that were made in what was once called the Francevillian inland sea — an oxygenated and shallow marine environment that existed during the Paleoproterozoic, an eralasting from about 2.5 billion to 1.6 billion years ago.

Until now, the oldest traces of motility (an organism’s ability to move independently using metabolic energy) dated to about 600 million years ago. But now, newly analyzed fossils suggest that motility dates back to 2.1 billion years ago. (Scale bar: 1 centimeter, or 0.4 inches.) Credit: A. El Albani/IC2MP/CNRS – Université de Poitiers

After collecting hundreds of specimens from the ancient inland sea, the scientists in the recent study found fossilized tunnels. These structures indicated that some ancient multicellular organisms were complex enough to scoot through the mud, said first author Abderrazak El Albani, a professor of paleobiology and geochemistry at IC2MP, an institute of the University of Poitiers and the the National Center for Scientific Research (CNRS) in France.

There is a modern analogue to this weird slug-like creature. During times of starvation, some cellular slime molds aggregate together in what is called a “migratory slug phase,” so they can look for food together, El Albani said.

The tunnels these ancient critters left behind are small, with a diameter of up to 2.3 inches (6 centimeters) and a length of up to 6.7 inches (17 cm). What’s more, the tunnels appear to be made by something that moved laterally and vertically through the muck, El Albani told Live Science. To determine for sure that these tunnels were left by living creatures, the researchers analyzed the structures in several ways. For starters, the scientists used an X-ray computed microtomography (micro-CT) scan to analyze the specimen in 3D (see the above video).

The team also analyzed the chemical components in the trace fossils, finding that these traces were biological in origin and also matched the age of the 2.1-billion-year-old sediment around them. Moreover, the tunnels were next to fossilized microbial mats, known as biofilms. Perhaps the strange, slug-like beast grazed on these microbial “carpets,” the researchers said.

The tubes in the sample are filled with pyrite crystals, which are generated by the transformation by bacteria of biological tissue. The parallel horizontal layers are fossilized microbial mats.Credit: Copyright A. El Albani & A. Mazurier/IC2MP/CNRS – Université de Poitiers

While much about this critter remains a mystery, its existence raises new questions about the history of life, El Abani said. Was this the first time a complex organism moved, and was movement perfected later on? Or was this creature’s experiment cut short when atmospheric oxygen levels dropped drastically about 2 billion years ago, only for this kind of movement to resurface much later? [7 Theories on the Origin of Life]

But not everyone thinks these tunnels represent the oldest proof of motility.

“The claim sounds really imprecise,” Tanja Bosak, an associate professor of geobiology in the Department of Earth, Atmospheric and Planetary Sciences at the Massachusetts Institute of Technology, told Live Science in an email. “Perhaps they are referring to something macroscopic moving — there are much older rocks (stromatolites) with shapes and textures that require the former presence of motile microbes.”

She emphasized that while she didn’t have time for an in-depth reading of the study, Bosak told Live Science, “I hope that they discuss this somewhere and tone down the splashy claims at least a little.”

The study was published online yesterday (Feb. 11) in the journal Proceedings of the National Academy of Sciences.

Source: Article By Laura Geggel, Senior Writer , www.livescience.com

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WFS News: Ancient Passerines Fossils reveals Oldest Finch-Beaked Birds

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A 52-million-year fossil of a “perching bird” has been found in Wyoming with its feathers still attached, a discovery that “no one’s ever seen before.”

Also known as passerines, the perching bird was discovered in Fossil Lake, WY. Passerines are well-known for eating seeds, as most modern-day birds do and account for approximately 65 percent of the 10,000 different species of birds alive today.

 

 

Figure 1Morphology of Eofringillirostrum (A) Photograph and (B) line drawing of the holotype skeleton of Eofringillirostrum boudreauxi (FMNH PA 793) with enlargements showing details of the (C) skull and (D) foot, and (E) line drawing of foot. (F) Holotype slab (IRSNB Av 128a) and (G) counterslab (IRSNB Av 128b) of Eofringillirostrum parvulum with enlargements showing details of (H) skull and (I) carpometacarpus; for contrast enhancement, the specimen was coated with ammonium chloride. Abbreviations: at: accessory trochlea, br: base of the main body of fourth metatarsal trochlea (articular end broken off); d-I – d-IV: pedal digits I – IV, dvf: distal vascular foramen, ext: extensor process, int: intermetacarpal process, ot: ossified tendon, py: pygostyle, rp: retroarticular process, sup: dorsal supracondylar process, tr: tracheal rings. Arrows in (D) indicate borders of intermetacarpal process. Grey shaded regions in (B) indicate portions of the carpometacarpus that were displaced during splitting of the slab. See also Figure S2.

Figure 1Morphology of Eofringillirostrum
(A) Photograph and (B) line drawing of the holotype skeleton of Eofringillirostrum boudreauxi (FMNH PA 793) with enlargements showing details of the (C) skull and (D) foot, and (E) line drawing of foot. (F) Holotype slab (IRSNB Av 128a) and (G) counterslab (IRSNB Av 128b) of Eofringillirostrum parvulum with enlargements showing details of (H) skull and (I) carpometacarpus; for contrast enhancement, the specimen was coated with ammonium chloride. Abbreviations: at: accessory trochlea, br: base of the main body of fourth metatarsal trochlea (articular end broken off); d-I – d-IV: pedal digits I – IV, dvf: distal vascular foramen, ext: extensor process, int: intermetacarpal process, ot: ossified tendon, py: pygostyle, rp: retroarticular process, sup: dorsal supracondylar process, tr: tracheal rings. Arrows in (D) indicate borders of intermetacarpal process. Grey shaded regions in (B) indicate portions of the carpometacarpus that were displaced during splitting of the slab. See also Figure S2.

FIRST DINOSAUR FEATHER EVER DISCOVERED REVEALS MYSTERIOUS SECRETS

The study has been published in the scientific journal Current Biology.

Now known as Eofringillirostrum boudreauxi, the bird had a “finch-like beak,” similar to modern day finches and sparrows, which could give clues as to its diet.

Figure 2Phylogenetic Relationships of Early Passerines Strict consensus of 394 most parsimonious trees (707 steps, RC = 0.174, RI = 0.626) based on analysis of 146 morphological characters enforcing the backbone constraint and divergence dates from [20]. Bootstrap support values are shown above the branches they pertain to, though note nodes that are constrained may receive artificially high support (e.g., Psittaciformes). Character list, scorings, and additional details of analyses are provided in the Supplemental Information and Figure S3.

Figure 2Phylogenetic Relationships of Early Passerines
Strict consensus of 394 most parsimonious trees (707 steps, RC = 0.174, RI = 0.626) based on analysis of 146 morphological characters enforcing the backbone constraint and divergence dates from [20]. Bootstrap support values are shown above the branches they pertain to, though note nodes that are constrained may receive artificially high support (e.g., Psittaciformes). Character list, scorings, and additional details of analyses are provided in the Supplemental Information and Figure S3.

“These bills are particularly well-suited for consuming small, hard seeds,” Daniel Ksepka, the paper’s lead author, curator at the Bruce Museum in Connecticut, said in the statement.

“The earliest birds probably ate insects and fish, some may have been eating small lizards,” Grande added. “Until this discovery, we did not know much about the ecology of early passerines. E. boudreauxi gives us an important look at this.”

Stem and Crown Passerines (A–P) Images and comparative line drawings of the skull in (A–H) Eocene stem passerines and photographs of the head and line drawings of the skull in (I–P) crown passerines with a similar bill shape. Fossil taxa: (A and B) Morsoravis sp. (FMNH PA789), (C and D) Eofringillirostrum boudreauxi (FMNH PA 793), (E and F) Pumiliornis tessellatus (SMF-ME 11414a) and (G and H) Psittacopes lepidus (SMF-ME 1279). Extant taxa: (I and J) Catharus guttatus (Hermit Thrush, Turdidae), (K and L) Spinus tristis (American Goldfinch, Fringillidae), (M and N) Aethopyga saturata (Black-throated Sunbird, Nectariniidae) and (O and P) Panurus biarmicus (Bearded Reedling, Panuridae). Photo credits and sources for line drawings are provided in the Supplemental Information. Not to scale.

Stem and Crown Passerines
(A–P) Images and comparative line drawings of the skull in (A–H) Eocene stem passerines and photographs of the head and line drawings of the skull in (I–P) crown passerines with a similar bill shape. Fossil taxa: (A and B) Morsoravis sp. (FMNH PA789), (C and D) Eofringillirostrum boudreauxi (FMNH PA 793), (E and F) Pumiliornis tessellatus (SMF-ME 11414a) and (G and H) Psittacopes lepidus (SMF-ME 1279). Extant taxa: (I and J) Catharus guttatus (Hermit Thrush, Turdidae), (K and L) Spinus tristis (American Goldfinch, Fringillidae), (M and N) Aethopyga saturata (Black-throated Sunbird, Nectariniidae) and (O and P) Panurus biarmicus (Bearded Reedling, Panuridae). Photo credits and sources for line drawings are provided in the Supplemental Information. Not to scale.

Fossil Lake has been home to several discoveries of past species, including birds, reptiles and early mammals, due in large part to what has been described as “perfect conditions.”

“We have spent so much time excavating this locality, that we have a record of even the very rare things,” Grande said.

TRIASSIC ‘LIZARD KING’ RULED ANTARCTICA BEFORE THE DINOSAUR

Fossil Lake provides a rare look into a world after the dinosaurs went extinct, but before mammals really started to take off and become the dominant form of life on Earth.

“I’ve been going to Fossil Lake every year for the last 35 years, and finding this bird is one of the reasons I keep going back. It’s so rich,” Grande added. “We keep finding things that no one’s ever seen before.”

Sources:Current Biology and Fox news

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WFS News: kangaroo fossil reveals origin of marsupial hop

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Artistic reconstruction showing the balbarid kangaroo relative Nambaroo gillespieae (top left) ( Peter Shouten/Australian Geographic )

Artistic reconstruction showing the balbarid kangaroo relative Nambaroo gillespieae (top left)                                                                         ( Peter Shouten/Australian Geographic )Fossils unearthed in the Australian bush have provided new insights into how the kangaroo got its hop.

The 20-million-year-old remains belong to a long-extinct species of kangaroo relative that not only hopped but also bounded along on all fours as well as climbed.

Known as balbarids, these creatures reveal how the distinctive anatomy of these marsupials allowed them to conquer an entire continent.

The origin of the kangaroo’s distinctive method of getting around has been shrouded in mystery, as ancient skeletons belonging to their ancestors are rare.

“The long held idea is that the kangaroo hop evolved in response to climate change, with the spread of arid grasslands opening up new habitats that selected for high speed hopping gaits,” Dr Benjamin Kear, a palaeontologist at Uppsala University told The Independent.

While some other animals, including the hopping mouse, have adopted a similar gait, kangaroos have unique anatomy to facilitate this highly efficient mode of locomotion.

To find out if the same was true of balbarids, Dr Kear and his colleagues analysed the few bones they had unearthed belonging to one known as Nambaroo gillespieae, comparing them to different modern relatives that live in trees and on the plains.

Their results, published in the journal Royal Society Open Science, challenged the idea that kangaroos began hopping on Australia’s arid plains.

The scientists said these creatures appear to have evolved a versatile anatomy to scramble around their forest environment.

“The iconic kangaroo body plan is therefore extremely adaptable, and was probably a key to their success over the last 20 million years or more,” said Dr Kear.

It was not enough to save the balbarids, however, and the team think these creatures were probably driven to extinction as their forest homes shrunk.

“On the other hand, the ancestors of modern kangaroos used the same suite of locomotory morphologies to exploit newly emerging open habitats, and thus gave rise to one of the most successful mammal radiations on the Australian landmass today,” said Dr Kear.

Source: Article by  Josh Gabbatiss,Science Correspondent,Independent.

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WFS News: Detection of lost calamus challenges identity of isolated Archaeopteryx feather

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Abstract

Scientific Reports volume 9, Article number: 1182 (2019)

In 1862, a fossil feather from the Solnhofen quarries was described as the holotype of the iconic Archaeopteryx lithographica. The isolated feather’s identification has been problematic, and the fossil was considered either a primary, secondary or, most recently, a primary covert. The specimen is surrounded by the ‘mystery of the missing quill’. The calamus described in the original paper is unseen today, even under x-ray fluorescence and UV imaging, challenging its original existence. We answer this question using Laser-Stimulated Fluorescence (LSF) through the recovery of the geochemical halo from the original calamus matching the published description. Our study therefore shows that new techniques applied to well-studied iconic fossils can still provide valuable insights. The morphology of the complete feather excludes it as a primary, secondary or tail feather of Archaeopteryx. However, it could be a covert or a contour feather, especially since the latter are not well known in Archaeopteryx. The possibility remains that it stems from a different feathered dinosaur that lived in the Solnhofen Archipelago. The most recent analysis of the isolated feather considers it to be a primary covert. If this is the case, it lacks a distinct s-shaped centerline found in modern primary coverts that appears to be documented here for the first time.

Introduction

Arguably one of the best known and most iconic of fossil vertebrates, specimens of the “urvogel” Archaeopteryx have been found for more than a century in the Solnhofen limestones of Southern Germany1. As the first feather fossil ever discovered1,2, the isolated feather long rivaled the London specimen as the holotype of Archaeopteryx lithographica, before the latter was eventually designated as a neotype3. This fossil is represented by two slabs, which are in the collections of museums in Berlin and Munich, respectively. The known specimens of Archaeopteryx (11 or 12: the urvogel identity of one specimen has recently been challenged4,5) include some with feathers preserved as limestone impressions. This is contrasted by the isolated feather, which has a dark coloration and preserves as a film of carbon6,7,8,9,10,11 or manganese dioxide1. Most notably, the specimen has been characterized by the mystery of the “missing quill” – the originally reported calamus is today invisible in the fossil10.

Previous analyses of the isolated feather have been controversial, with disparate identifications as a primary (possibly a remicle of a larger specimen7; distal primary12), secondary1,7 (found as a distal secondary when compared to Columba and Pica7) and primary covert8. The lack of a preserved calamus added to the difficulty of the task. The calamus was first described and drawn in 18622, but no obvious evidence of it remains today10 (Fig. 1). Possible explanations for the lack of a visible calamus on the more complete Berlin slab could be from damage incurred during past cleaning, re-preparation or handling of the slab (finger contact e.g. Fig. S2) as well as repeated exposure to daylight. However, there is no definitive evidence that attributes such damage to these particular sources. X-ray fluorescence13 and UV imaging studies of the feather did not report the missing quill (Figs 5, 6 of Plate 9 and Figs 1,2 of Plate 10 in14; Fig. 5.8 of1).

The isolated Archaeopteryx feather, Berlin specimen MB.Av.100. (A) As it looks today under white light (see Plates 1 & 5 [Fig. 1] of7, Fig. 1A of8 and Plate 10 of14). (B) Original drawing from 1862 by von Meyer2. (C) Laser-Stimulated Fluorescence (LSF) showing the halo of the missing calamus (negative image). See Fig. S2 for additional images of the main slab, specimen BSP 1869 VIII 1 (‘Munich slab’). Scale bar 1 cm.

The isolated Archaeopteryx feather, Berlin specimen MB.Av.100. (A) As it looks today under white light (see Plates 1 & 5 [Fig. 1] of7, Fig. 1A of8 and Plate 10 of14). (B) Original drawing from 1862 by von Meyer2. (C) Laser-Stimulated Fluorescence (LSF) showing the halo of the missing calamus (negative image). See Fig. S2 for additional images of the main slab, specimen BSP 1869 VIII 1 (‘Munich slab’). Scale bar 1 cm.

During an examination of the Berlin slab, a geochemical halo of the missing calamus was recovered for the first time using Laser-Stimulated Fluorescence (Fig. 1). This technique uses a high power laser to reveal geochemical differences in the specimen and matrix which fluoresce with different colors15,16,17 (see Materials and Methods). The length and width of the calamus halo matches that of the original published description2 (Fig. 1). Microscopic examination revealed past preparation had engraved around the outline of the feather and inadvertently prepared away the calamus at some unknown point in the past. Thus, the recovered geochemical halo is a chemical breakdown residue fluorescing immediately beneath the surface of the original carbon or manganese dioxide film.The feathers are clearly defined in many Archaeopteryx skeletons1. The feather impressions from some of the more complete specimens allows for detailed morphologic measurements1,18. The general morphology of Archaeopteryx feathers is considered similar to modern birds, allowing cautious comparisons with living taxa1.

As in extant birds, the primaries of Archaeopteryx are characteristically straight and have vane asymmetry19. Their straightness does not match the isolated feather and they are also generally more asymmetrically vaned. The isolated feather’s identification as a primary feather has also been historically argued against1,7Archaeopteryx lacks a bastard wing (alula)1, so the identification of the isolated feather as an alula feather of Archaeopteryx can be excluded.

The isolated feather is also not a tail feather (rectrix) of Archaeopteryx. The distal rectrices of Archaeopteryx are extremely long and symmetrical in outline at the tip (eleventh specimen: Fig. 2E of18), two features absent in the isolated feather. The isolated feather shares a general asymmetry in outline and rachis position with the lateral rectrices, but the curvature of the rachis is too severe in the isolated feather to form the frond pattern seen in Archaeopteryx (eleventh specimen: Fig. 2F of18). The tail feathers of the London specimen lack asymmetrical vanes, which also contrasts with the morphology of the isolated feather1.

The secondary feathers in the known Archaeopteryx specimens are the closest matches to the general feather outline of the isolated feather. Unfortunately, no other feathers stand alone in other Archaeopteryxspecimens with feather preservation, but measurements of the isolated feather can be compared to the secondaries of the Berlin specimen, which preserves the most complete wing feathering of Archaeopteryx1,14. The outline of the isolated feather was superimposed onto a version scaled to match the width of the most similar secondary feather in the Berlin specimen (Fig. 2). This comparison reveals that the isolated feather is 1/3 shorter than required to scale to the secondaries of the Berlin Archaeopteryx wing. Unfortunately, the specimens larger than the Berlin specimen (London and Solnhofen) as well as the smallest urvogel (Eichstätt) both have poorly preserved feathering1, so this cannot be compared across ontogeny.

A range of secondary feather counts has previously been reconstructed along the ulna of the Berlin specimen (ten20, twelve21, fourteen (Fig. 6.18 of1) and twelve to fifteen22), but the reliability of these counts has been questioned18. Scaling the isolated feather to match the length and spatial overlap in the wing of the Berlin specimen (Fig. S7) shows that 7 secondaries could fit along the wing, significantly fewer feathers than past reconstructions. If the isolated feather was from a subadult as suggested by Wellnhofer1, then the feather count on the shorter ulna would be even less. As mentioned, this cannot be compared across ontogeny as the largest and smallest Archaeopteryx specimens (Solnhofen and Eichstätt) have poorly preserved feathering1. Nevertheless, these data raise questions about the fit of the isolated feather to the wing of Archaeopteryx.

The remaining possibilities for the isolated feather are as a covert or a contour feather. However, a determination is less straightforward. Little is known about the contour feathers of Archaeopteryx, although modern contour feathers typically have less robust calami than the isolated feather. As a covert, the isolated feather is very different to those of extant birds. In living birds, the secondary coverts attach to the calamus of the secondary flight feathers at an angle (Fig. S8). This configuration necessitates a shorter calamus than the primary coverts, which are in place alongside the primary feather calamus. The robust calamus of the isolated feather is therefore too large for a secondary covert, so this identification is not supported. The most recent analysis of the isolated feather considered it to be a primary covert8. The size-normalized calamus-rachis centerlines of primary coverts from 24 modern birds, including those of different body sizes, were compared to the isolated feather (Fig. 3). All possess a calamus-rachis centerline that curves towards the leading edge of the wing from the centerline of the calamus, unlike the rachis centerlines of the other feather types present in the same wing specimens7,19,23,24 (Figs 3S3S6). This ‘S-shaped’ centerline described here for the first time, appears to be a defining characteristic of primary coverts across a very broad range of modern species, including the palaeognath tinamou. In contrast, the centerline of the isolated Solnhofen feather curves strongly toward the wing’s trailing edge (see blue line in Fig. 3) so does not match the morphology of primary coverts in modern birds7,19,23,24.

Overlay of the isolated feather MB.Av.100 scaled to the same size as the most similar secondary feather in the wing of the Berlin Archaeopteryx MB.Av.101. Significant foreshortening of the isolated feather does not support its association with Archaeopteryx.

Overlay of the isolated feather MB.Av.100 scaled to the same size as the most similar secondary feather in the wing of the Berlin Archaeopteryx MB.Av.101. Significant foreshortening of the isolated feather does not support its association with Archaeopteryx.                                                                                                                                                                                                                                      

Size-normalized centerline calamus-rachis traces for the primary coverts of 24 modern birds compared to the trace of the isolated feather (Berlin specimen, MB.Av.100). The blue line is the isolated feather’s trace whilst the orange line is from the common magpie (Pica pica, Fig. S3) whose wing has been cited as the isolated feather’s closest modern match1,7. In brown is the centerline trace from a modern Undulated Tinamou (Crypturellus undulatus UWBM 71526, Fig. S4), which belongs to the only groups of extant palaeognaths with flight capabilities. The yellow zone represents the area covered by the traces of all 24 measured feathers, including a 1.5% error zone allowing for taphonomic flex (see Fig. S1). In all cases the isolated feathers centerline is a large departure from modern primary coverts.

Size-normalized centerline calamus-rachis traces for the primary coverts of 24 modern birds compared to the trace of the isolated feather (Berlin specimen, MB.Av.100). The blue line is the isolated feather’s trace whilst the orange line is from the common magpie (Pica pica, Fig. S3) whose wing has been cited as the isolated feather’s closest modern match1,7. In brown is the centerline trace from a modern Undulated Tinamou (Crypturellus undulatus UWBM 71526, Fig. S4), which belongs to the only groups of extant palaeognaths with flight capabilities. The yellow zone represents the area covered by the traces of all 24 measured feathers, including a 1.5% error zone allowing for taphonomic flex (see Fig. S1). In all cases the isolated feathers centerline is a large departure from modern primary coverts.

In summary, the isolated feather is not conformal to known Archaeopteryx specimens as a primary, secondary or tail feather. Its preservation as a dark film also differentiates it from all other known specimens1,6. The isolated feather as argued here lacks any close morphological connection to the 11 or 12 known Archaeopteryxskeletons (see status of Haarlem specimen4,5), but not all feathers of Archaeopteryx are known. However, based on known feather preservation in Archaeopteryx, this study raises the possibility that the isolated feather may belong to another basal avialan or even a non-avialan pennaraptoran, increasing the low theropod diversity of the Solnhofen Archipelago1,4,25,26,27. This hypothesis would be in agreement with comments made in Opinion 2283 (Case 3390) of the ICZN Commission3 as well as the recent removal of the Haarlem specimen from Archaeopteryx4. The feather remains an enigma so we caution against the isolated feather’s association with Archaeopteryx.

Material and Methods

Archaeopteryx specimens studied

  1. 1.The single feather: BSP 1869 VIII 1 (main slab, ‘Munich slab’), Bavarian State Collection of Paleontology and Geology, Munich; MB Av.100 (counterslab, ‘Berlin slab’), Museum für Naturkunde, Berlin, Germany.
  2. 2.London specimen: NHMUK 37001 (main slab), Natural History Museum, London, UK.
  3. 3.Berlin specimen: MB.Av.101 (main and counterslab), Museum für Naturkunde, Berlin, Germany.
  4. 4.Haarlem specimen: TM 6928 (main slab), Teylers Museum, Haarlem, Netherlands; TM 6929 (counterslab).
  5. 5.Eichstätt specimen: JM 2257 (main and counterslab), Jura Museum, Willibaldsburg, Germany.
  6. 6.Solnhofen specimen: BMMS 500 (main slab), Bürgermeister Müller Museum, Solnhofen, Germany.
  7. 7.Munich specimen: BSP 1999 I 50 (main and counterslab), Bayerische Staatssammlung für Paläontologie und Geologie, Munich, Germany.
  8. 8.Daiting specimen: unknown specimen number, unknown current repository details.
  9. 9.Bürgermeister Müller (‘chicken wing’) specimen: unknown specimen number, on permanent loan to Bürgermeister Müller Museum by the families Ottmann and Steil.
  10. 10.Thermopolis specimen: WDC CSG 100 (main slab). Wyoming Dinosaur Center, Thermopolis, USA.
  11. 11.Eleventh specimen: no. 02923 on the register of cultural objects of national importance of Germany (Verzeichnis national wertvollen Kulturgutes), on long-term loan to Bürgermeister Müller Museum.

Modern bird specimens studied

Museum collections.

  1. 1.Tinamou (Crypturellus undulatus) – UWBM 71526; University of Washington Burke Museum of Natural History and Culture, Seattle, USA) (Fig. S4).
  2. 2.Common magpie (Pica pica) – FSA2016-01; Foundation for Scientific Advancement, Sierra Vista, USA).Atlas of avian feathers at www.vogelfedern.de/index-e.htm.
  3. 3.Common Crane Grus grus.
  4. 4.Tundra Swan Cygnus columbianus.
  5. 5.Common Magpie Pica pica (Fig. S3).Atlas of avian feathers atwww.michelklemann.nl/verensite/start/index.html.
  6. 6.Peregrine Falcon Falco peregrinus.
  7. 7.Tufted Duck Aythya fuligula.
  8. 8.Black Headed Gull Larus ridibundus, example 1.
  9. 9.Sparrowhawk Accipiter nisus, example 5.
  10. 10.Mallard Anas platyrhynchos, example 3.
  11. 11.Swift Apus apus, example 4.
  12. 12.Little Ringed Plover Charadrius dubius.
  13. 13.Skylark Alauda arvensis.
  14. 14.Hen Harrier Circus cyaneus.
  15. 15.Long Tailed Duck Clangula hyemalis.
  16. 16.Lilac Breasted Roller Coracias caudatus.
  17. 17.Quail Coturnix coturnix.
  18. 18.Long-eared Owl Asio otus.
  19. 19.Razorbill Alca torda, example 1 (Fig. S6).
  20. 20.Teal Anas crecca, example 1.
  21. 21.Two Barred Crossbill Loxia leucoptera, example 3.
  22. 22.Giant Kingfisher Megaceryle maxima.
  23. 23.Black Kite Milvus migrans.
  24. 24.Whimberel Numenius phaeopus.
  25. 25.Eurasian Curlew Numenius arquata (Fig. S5).
  26. 26.Rook Corvus frugilegus.

Laser-Stimulated Fluorescence (LSF) imaging was performed according to the protocol of Kaye et al.15,17 so only an abbreviated version is provided here. A 405 nanometer laser diode was used to fluoresce the specimen following standard laser safety protocol. Thirty second time exposed images were taken with a Nikon D810 camera and 425 nanometer blocking filter. Post processing (equalization, saturation and colour balance) was performed in Photoshop CS6.

Primary covert feather analysis was performed from photographs. These were sourced from museum collections and the Vogel Federn and Michel Klemann online feather atlases23,24. The feathers of the latter two collections were flat bed scanned (see Supplementary Materials for discussion of flattening-related feather taphonomy). Feather centerlines were overlaid in Photoshop CS6, all centerlines were scaled to the same length.

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WFS News: Dinosaur-like archosaur Smok wawelski was crushing bones like a hyena

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Coprolites, or fossil droppings, of the dinosaur-like archosaur Smok wawelski contain lots of chewed-up bone fragments. This led researchers at Uppsala University to conclude that this top predator was exploiting bones for salt and marrow, a behavior often linked to mammals but seldom to archosaurs.

Sketch-drawing of the vertebrate faunal assemblage of the Lisowice site (modified from Niedźwiedzki)10. (a) Large, theropod-like predatory archosaur (Smok wawelski); (b) large temnospondyl amphibian (Cyclotosaurus sp.); (c) small predatory dinosaurs (Neotheropoda indet.); (d) temnospondyl amphibian (Gerrothorax sp.); (e) small basal crocodylomorph (Crocodylomorpha indet.); (f) small diapsid (Choristodere-like animal); (g) hybodont sharks (Polyacrodus and Hybodus); (h) coelacanth fish; (i) dipnoan fish (Ptychoceratodus sp.); (j) actinopterygian fish; (k) gigantic dicynodont; (l) dinosauriforms or early dinosaurs (Dinosauriformes indet. or Dinosauria indet.); (m) small lepidosauromorphs (Sphenodontia indet.); (n) pterosaurs (Pterosauria indet.); (o) early mammaliaform (Hallautherium sp.).

Sketch-drawing of the vertebrate faunal assemblage of the Lisowice site (modified from Niedźwiedzki)10. (a) Large, theropod-like predatory archosaur (Smok wawelski); (b) large temnospondyl amphibian (Cyclotosaurus sp.); (c) small predatory dinosaurs (Neotheropoda indet.); (d) temnospondyl amphibian (Gerrothorax sp.); (e) small basal crocodylomorph (Crocodylomorpha indet.); (f) small diapsid (Choristodere-like animal); (g) hybodont sharks (Polyacrodus and Hybodus); (h) coelacanth fish; (i) dipnoan fish (Ptychoceratodus sp.); (j) actinopterygian fish; (k) gigantic dicynodont; (l) dinosauriforms or early dinosaurs (Dinosauriformes indet. or Dinosauria indet.); (m) small lepidosauromorphs (Sphenodontia indet.); (n) pterosaurs (Pterosauria indet.); (o) early mammaliaform (Hallautherium sp.).

Most predatory dinosaurs used their blade-like teeth to feed on the flesh of their prey, but they are commonly not thought to be much of bone crushers. The major exception is seen in the large tyrannosaurids, such as Tyrannosaurus rex, that roamed North America toward the end of the age of dinosaurs. The tyrannosaurids are thought to have been osteophagous (voluntarily exploiting bone) based on findings of bone-rich coprolites, bite-marked bones, and their robust teeth being commonly worn.

Large to medium-sized, elongated, bone-bearing and phosphate-rich S. wawelski coprolites from Lisowice, Upper Triassic, Poland. (a) ZPAL V.33/344. (b) ZPAL V.33/342. (c) ZPAL V.33/346. (d) ZPAL V.33/604. (e) ZPAL V.33/345. (f) ZPAL V.33/600. (g) ZPAL V.33/343. (h) ZPAL V.33/340. (i) ZPAL V.33/341. (a–e,h,i) Elongated specimens. (f,g) Elongated but slightly more irregular specimens. Scale bars: 1 cm.

Large to medium-sized, elongated, bone-bearing and phosphate-rich S. wawelski coprolites from Lisowice, Upper Triassic, Poland. (a) ZPAL V.33/344. (b) ZPAL V.33/342. (c) ZPAL V.33/346. (d) ZPAL V.33/604. (e) ZPAL V.33/345. (f) ZPAL V.33/600. (g) ZPAL V.33/343. (h) ZPAL V.33/340. (i) ZPAL V.33/341. (a–e,h,i) Elongated specimens. (f,g) Elongated but slightly more irregular specimens. Scale bars: 1 cm.

In a study published in Scientific Reports, researchers from Uppsala University were able to link ten large coprolites to Smok wawelski, a top predator of a Late Triassic (210 million year old) assemblage unearthed in Poland. This bipedal, 5-6 meters long animal lived some 140 million years before the tyrannosaurids of North America and had a T. rex-like appearance, although it is not fully clear whether it was a true dinosaur or a dinosaur-like precursor.

Inclusions and matrix composition of the large coprolites. (a) Specimen ZPAL V.33/340 with bone and plant fragments exposed on the surface. (b,c) SEM images of coprolite matrix with micron-sized spherical structures (b) and section of a fish scale (c) preserved in the coprolite matrix. (d–f) Virtual sections showing bone inclusions (d,e - fragments of bones; f - tooth). (g,h) EDS spectra of matrix from two coprolites displaying a calcium phosphatic composition (g – ZPAL V.33/600; h – ZPAL V.33/604). Scale bars: a - 10 mm; b - 0.2 mm; c - 1 mm; d - 10 mm; e - 3 mm; f - 2 mm.

Inclusions and matrix composition of the large coprolites. (a) Specimen ZPAL V.33/340 with bone and plant fragments exposed on the surface. (b,c) SEM images of coprolite matrix with micron-sized spherical structures (b) and section of a fish scale (c) preserved in the coprolite matrix. (d–f) Virtual sections showing bone inclusions (d,e – fragments of bones; f – tooth). (g,h) EDS spectra of matrix from two coprolites displaying a calcium phosphatic composition (g – ZPAL V.33/600; h – ZPAL V.33/604). Scale bars: a – 10 mm; b – 0.2 mm; c – 1 mm; d – 10 mm; e – 3 mm; f – 2 mm.

Three of the coprolites were scanned using synchrotron microtomography. This method has just recently been applied to coprolites and works somewhat like a CT scanner in a hospital, with the difference that the energy in the x-ray beams is much stronger. This makes it possible to visualize internal structures in fossils in three dimensions.

The coprolites were shown to contain up to 50 percent of bones from prey animals such as large amphibians and juvenile dicynodonts. Several crushed serrated teeth, probably belonging to the coprolite producer itself, were also found in the coprolites. This means that the teeth were repeatedly crushed against the hard food items (and involuntarily ingested) and replaced by new ones.

Virtual reconstructions of the three scanned specimens (semi-transparent), showing the enclosed bones (white) and tooth inclusions (orange). Gross morphology and contents of coprolites ZPAL V.33/344 (a); ZPAL V.33/341 (b), and ZPAL V.33/345 (c).

Virtual reconstructions of the three scanned specimens (semi-transparent), showing the enclosed bones (white) and tooth inclusions (orange). Gross morphology and contents of coprolites ZPAL V.33/344 (a); ZPAL V.33/341 (b), and ZPAL V.33/345 (c).

Further evidence for a bone-crushing behaviour can also be found in the fossils from the same bone beds in Poland. These include worn teeth and bone-rich fossil regurgitates from Smok wawelski, as well as numerous crushed or bite-marked bones.

Several of the anatomical characters related to osteophagy, such as a massive head and robust body, seem to be shared by S. wawelski and the tyrannosaurids, despite them being distantly related and living 140 million years apart. These large predators therefore seem to provide evidence of similar feeding adaptations being independently acquired at the beginning and end of the age of dinosaurs.

  1. Martin Qvarnström, Per E. Ahlberg, Grzegorz Niedźwiedzki. Tyrannosaurid-like osteophagy by a Triassic archosaurScientific Reports, 2019; 9 (1) DOI: 10.1038/s41598-018-37540-4
2. Uppsala University. “The 210-million-year-old Smok was crushing bones like a hyena.” ScienceDaily. ScienceDaily, 30 January 2019. <www.sciencedaily.com/releases/2019/01/190130161643.htm>.
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WFS News: Pterosaurs: Fur flies over feathery fossils

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What pterosaurs might have looked like @ YUAN ZHANG/NATURE ECOLOGY & EVOLUTION

What pterosaurs might have looked like

Two exceptionally well preserved fossils give a new picture of the pterosaurs, the flying reptiles that lived at the time of the dinosaurs.

Scientists believe the creatures may have had feathers, and looked something like brown bats with fuzzy wings.

The surprise discovery suggests feathers evolved not in birds, nor dinosaurs, but in more distant times.

Pterosaurs were the closest relatives of dinosaurs, sharing a common ancestor about 250 million years ago.

“We would suggest – tentatively – that it would be worth considering that feathers originated much earlier than we thought,” Prof Mike Benton, from the University of Bristol, told BBC News.

Hailing from China, the 160-million-year-old fossils are of two different pterosaurs, one of which is newly discovered.

Strange feathery creatures

In depth analysis shows that as well as fur – which has been suggested before – the flying reptiles had feathers like some dinosaurs, including the theropods.

“If I just saw these fluffy bits on their own, I would swear they were from a theropod dinosaur,” said Dr Steve Brusatte of the University of Edinburgh, who was not part of the study.

“This means feathers were not a bird innovation, not even a dinosaur innovation, but evolved first in a much more distant ancestor.

“The age of dinosaurs was full of all sorts of strange feathery creatures!”

BAOYU JIANG, MICHAEL BENTON ET AL./NATURE ECOLOGY Image caption Are these feathers?

BAOYU JIANG, MICHAEL BENTON ET AL./NATURE ECOLOGY
                                                         Are these feathers?

The researchers found that the pterosaurs had four different kinds of covering, including fuzzy, fur over most of their body; and, on parts of the head and wings, three types of fibres similar to modern feathers.

The fluff and feathers are likely to have been important in heat regulation and aerodynamics.

“These structures on the pterosaur make it look a bit like a fruit bat, or something like that, a fuzzy hairy creature,” said Prof Benton, who worked on the discovery with colleagues in China.

“They fly with great out-stretched bony wings that carry a substantial membrane, a bit like a bat.”

Flight in the Jurassic skies

Questions still remain over whether these are true feathers. If they are, it would suggest that feathers appeared millions of years earlier than previously thought.

Alternatively, feathers could have evolved twice during the course of evolution.

Insects were the first group to achieve the ability to fly: they developed wings at least 320 million years ago.

Pterosaurs were the first vertebrates – animals with a backbone – to evolve powered flight, about 230 million years ago.

The research is published in Nature Ecology & Evolution.

Source: Article by 

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WFS News: Antarctanax,an Iguana-sized dinosaur from Antarctica

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Antarctica wasn’t always a frozen wasteland — 250 million years ago, it was covered in forests and rivers, and the temperature rarely dipped below freezing. It was also home to diverse wildlife, including early relatives of the dinosaurs. Scientists have just discovered the newest member of that family — an iguana-sized reptile whose name means “Antarctic king.”

A slab containing fossils of Antarctanax. Credit: Copyright Brandon Peecook, Field Museum

A slab containing fossils of Antarctanax. Credit: Copyright Brandon Peecook, Field Museum

“This new animal was an archosaur, an early relative of crocodiles and dinosaurs,” says Brandon Peecook, a Field Museum researcher and lead author of a paper in the Journal of Vertebrate Paleontology describing the new species. “On its own, it just looks a little like a lizard, but evolutionarily, it’s one of the first members of that big group. It tells us how dinosaurs and their closest relatives evolved and spread.”

The fossil skeleton is incomplete, but paleontologists still have a good feel for the animal, named Antarctanax shackletoni (the former means “Antarctic king,” the latter is a nod to polar explorer Ernest Shackleton). Based on its similarities to other fossil animals, Peecook and his coauthors (Roger Smith of the University of Witwatersrand and the Iziko South African Museum and Christian Sidor of the Burke Museum and University of Washington) surmise that Antarctanax was a carnivore that hunted bugs, early mammal relatives, and amphibians.

The most interesting thing about Antarctanax, though, is where it lived, and when. “The more we find out about prehistoric Antarctica, the weirder it is,” says Peecook, who is also affiliated with the Burke Museum. “We thought that Antarctic animals would be similar to the ones that were living in southern Africa, since those landmasses were joined back then. But we’re finding that Antarctica’s wildlife is surprisingly unique.”

About two million years before Antarctanax lived — the blink of an eye in geologic time — Earth underwent its biggest-ever mass extinction. Climate change, caused by volcanic eruptions, killed 90% of all animal life. The years immediately after that extinction event were an evolutionary free-for-all — with the slate wiped clean by the mass extinction, new groups of animals vied to fill the gaps. The archosaurs, including dinosaurs, were one of the groups that experienced enormous growth. “Before the mass extinction, archosaurs were only found around the Equator, but after it, they were everywhere,” says Peecook. “And Antarctica had a combination of these brand-new animals and stragglers of animals that were already extinct in most places — what paleontologists call ‘dead clades walking.’ You’ve got tomorrow’s animals and yesterday’s animals, cohabiting in a cool place.”

The fact that scientists have found Antarctanax helps bolster the idea that Antarctica was a place of rapid evolution and diversification after the mass extinction. “The more different kinds of animals we find, the more we learn about the pattern of archosaurs taking over after the mass extinction,” notes Peecook.

“Antarctica is one of those places on Earth, like the bottom of the sea, where we’re still in the very early stages of exploration,” says Peecook. “Antarctanax is our little part of discovering the history of Antarctica.”

Reference:Brandon R. Peecook, Roger M. H. Smith, Christian A. Sidor. A novel archosauromorph from Antarctica and an updated review of a high-latitude vertebrate assemblage in the wake of the end-Permian mass extinctionJournal of Vertebrate Paleontology, 2019; 1 DOI: 10.1080/02724634.2018.1536664

From: www.sciencedaily.com/releases/2019/01/190131084252.htm

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WFS News: Koreamegops samsiki,The ancient spider had eyes that shone in the dark

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The defining specimen of Koreamegops samsiki, a newfound species of spider that lived in what is now South Korea between 106 and 112 million years ago. PHOTOGRAPH BY PAUL ANTONY SELDEN

The defining specimen of Koreamegops samsiki, a newfound species of spider that lived in what is now South Korea between 106 and 112 million years ago.PHOTOGRAPH BY PAUL ANTONY SELDEN

IF YOU COULD time-travel to Korea 110 million years ago, you’d see an eerie spectacle if you walked out at night with a flashlight: Each sweep of your beam would make the landscape sparkle as innumerable spider eyes glinted in the dark.

In a new study in the Journal of Systematic Paleontology, a team led by Korea Polar Research Institute paleontologist Tae-Yoon Park unveils ten fossils of tiny spiders, each less than an inch wide. The remains contain two new species and a first for paleontology: a spider’s version of night-vision goggles.

In some animals’ eyeballs, a membrane called the tapetum (tuh-PEE-tuhm) sits behind the retina and reflects light back through it. If you’ve ever seen a cat’s eyes seem to glow green at night, that’s their tapeta at work. By giving the retinas a second chance to absorb light, tapeta boost the night vision of moths, cats, owls, and many other nocturnal animals. So, too, in these ancient spiders, whose silvery tapeta still shine in the fossils.

“They’re so reflective—they clearly stick out at you,” says study coauthor Paul Selden, a paleontologist at the University of Kansas. “That was a sort of eureka moment.”

The find sheds further light on the ancient behavior of spiders, some of modern Earth’s most important predators by mass.

“These fossils are extraordinary, and it’s always a thrill when something of the visual system is preserved,” Nathan Morehouse, a University of Cincinnati biologist who studies spider vision, writes in an email. “More exciting to me and other vision scientists is the glimpse that the tapetum offers into the lifestyle of these ancient animals. They were likely nocturnal hunters!”

The eyes have it

Some of the newfound spiders belong to an extinct group known as the lagonomegopids, some of which loosely resembled today’s jumping spiders. The new fossils are the first lagonomegopids ever found in rock—all previous fossils of the group come from amber, or fossilized tree resin. (See a feathered dinosaur’s tail preserved in amber.)

Before this study, all known fossils of lagonomegopids—an extinct group of spiders—had been found in amber, including this 99-million-year-old specimen. J. dalingwateri and K. samsiki are the first lagonomegopids ever found fossilized in rock. PHOTOGRAPH BY PAUL ANTONY SELDEN

Before this study, all known fossils of lagonomegopids—an extinct group of spiders—had been found in amber, including this 99-million-year-old specimen. J. dalingwateri and K. samsiki are the first lagonomegopids ever found fossilized in rock.PHOTOGRAPH BY PAUL ANTONY SELDEN

The landscape these spiders knew was very different from Korea today. Some 110 million years ago, the southern Korean peninsula was a shallow basin that formed as a nearby volcanic ridge expanded. Fish and bivalves thrived in the basin’s lakes and rivers. Dinosaurs and pterosaurs lived nearby, judging by the teeth they left behind.

After getting washed out into a lake within this basin, the spiders’ bodies ended up buried in the lake’s sediments. Minerals then replaced the spiders’ flesh: Even today, their legs show traces of the hairs that once covered them. The spiders laid undisturbed until several years ago, when collectors found them in two construction sites near the city of Jinju, one of which is now a parking lot.

Park’s team later learned that the fossils were of many different spider types, including the two new lagonomegopid species. One of the newly described spiders, Koreamegops samsiki, is named for Samsik Lee, the Korean collector who found it. The other, Jinjumegops dalingwateri, is named for British arachnologist John Dalingwater, a mentor of Selden’s who died of Parkinson’s disease in 2018.

Both new species have tapeta and enlarged secondary eyes, much like today’s wolf spiders and the prey-snaring spider Deinopis spinosa. While the fossil spiders’ eyes would have glittered as wolf spiders’ eyes do today, it’s far from a given that they hunted their prey in a similar way.

“The eyes [of K. samsiki and J. dalingwateri] are more at the corners of their head rather than the front, which is a bit of a mystery,” Selden says.

K. samsiki's right leg preserves traces of the spider's leg hairs. PHOTOGRAPH BY PAUL ANTONY SELDEN

K. samsiki’s right leg preserves traces of the spider’s leg hairs.PHOTOGRAPH BY PAUL ANTONY SELDEN

Depending on how the spiders’ retinas were built, their tapeta may have made their vision blurrier, Morehouse adds. Today’s nocturnal spiders get around this issue by spacing out the light-sensitive parts of their retinas. It’s unknown whether the ancient spiders struck a similar balance—but finding more fossils would help.

“How these fossil spiders navigated such tradeoffs will probably remain unknown unless an even better set of fossils shows up,” Morehouse writes. “I’d be excited to see what future studies uncover.”

Source: Article by Michael Greshko ,National Geographic’s science desk.

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WFS News: What’s the World’s Largest Dinosaur?

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The titanosaur dinosaur Dreadnoughtus schrani (pictured above) is the only supermassive dinosaur for which scientists have both the femur and humerus bones from the same individual. That makes it the largest dinosaur for which scientists can confidently calculate a mass. However, Argentinosaurus is likely the largest dinosaur, by mass, on record. Credit: Jennifer Hall

The titanosaur dinosaur Dreadnoughtus schrani (pictured above) is the only supermassive dinosaur for which scientists have both the femur and humerus bones from the same individual. That makes it the largest dinosaur for which scientists can confidently calculate a mass. However, Argentinosaurus is likely the largest dinosaur, by mass, on record.
Credit: Jennifer Hall

The battle for the title of world’s largest dinosaur is complicated.

Here’s why: Paleontologists rarely discover an entire skeleton. They’re more likely to uncover bone fragments and then try to estimate a profile of height and weight. Moreover, there are three categories for largest dinosaur on record: the weightiest, longest and tallest.

Starting with the weightiest, the gold-medal winner is likely Argentinosaurus. This supermassive titanosaur (a titanosaur is a giant sauropod, a long-necked and long-tailed herbivorous dinosaur) that lived about 100 million to 93 million years ago, during the Cretaceous period, in what is now (you guessed it) Argentina. [What Really Killed the Dinosaurs?]

But estimates of Argentinosaurus’ weight vary widely; the beast weighed 77 tons (70 metric tons), according to London’s Natural History Museum; up to 90 tons (82 metric tons), according to New York City’s American Museum of Natural History; and 110 tons (100 metric tons), according to BBC Earth.

It’s no wonder these calculations are all over the place. Argentinosaurus is known from just 13 bones: six midback vertebrae, five fragmentary hip vertebrae, one tibia (a shinbone) and one rib fragment. “There’s a femur that you’ll see with it [in some sketches], but that femur was found 15 kilometers [9 miles] away. So, who knows who that belongs to?” said Kenneth Lacovara, a professor of paleontology and geology and the dean of the School of Earth & Environment at Rowan University in Glassboro, New Jersey.

Another contender is Patagotitan, a titanosaur that weighed a whopping 69 tons (62 metric tons) when it lived about 100 million years ago in what is now Argentina. However, this weight was calculated based on a composite of individuals (there were six found in all), rather than just one dinosaur, Lacovara noted.

Which raises the question: How do scientists calculate the weight of an extinct animal? According to Lacovara, there are three ways.

Minimum shaft circumference method: Scientists measure the minimum circumference of the humerus (the upper arm bone) and femur (the thigh bone) from the same individual. Then, they plug these numbers in to a formula. The result is highly correlative with the animal’s mass. “It makes sense,” Lacovara said, “since all quadrupeds have to put all of the weight of the body on just those four bones. [So], the structural properties of those four bones are going to correlate closely with the mass.”

There are caveats, however. If the humerus and femur bone are from different individuals, as they were with Patagotitan, “the result is an estimate of a composite individual that never actually existed,” Lacovara said. Moreover, if only a single bone (a humerus or a femur) is used, the proportions of the missing bone are a guess. “Obviously, this introduces even more uncertainty,” he said. “Examples of this are Notocolossus and Paralititan.”

The largest known dinosaur that has a humerus and femur bone from the same individual is the 77-million-year-old Dreadnoughtus, a 65-ton (59 metric tons) titanosaur that Lacovara and his team excavated in Argentina.

Volumetric method: In this approach, researchers determine the body volume of the dinosaur and use that number to calculate the animal’s weight. This is challenging, because most titanosaur skeletons are incomplete. (Dreadnoughtus is the most complete, at 70 percent. Argentinosaurus is just 3.5 percent complete.) In addition, researchers have to guess how much space the lungs and other air-filled structures took up. Experts also have to speculate how “blubbery or shrink-wrapped” the skin on these dinosaurs was.

“In my view, this method is unworkable and lacks replicability, which is one of the hallmarks of science,” Lacovara said.

Wild guesses: This is how scientists estimate the weight of dinosaurs that don’t have any preserved humerus or femur bones. “Argentinosaurus, Futalognkosaurus and Puertasaurus are examples of this,” Lacovara said. “They are clearly huge, but there is no systematic, replicable way to estimate their mass.”

Moving on, what’s the longest dinosaur? That honor likely goes to Diplodocus or Mamenchisaurus, which can be described as slender and elongated sauropod dinosaurs, Lacovara said. “Both are known from reasonably complete skeletons, and both would be about 115 feet [35 m] long.” [How Did Dinosaurs Grow So Huge?]

In contrast, the titanosaurs were shorter. For example, Dreadnoughtuswas “only” about 85 feet (26 m) long.

But this category is still rife with uncertainty. “Some dinosaurs claimed to be the longest are extremely fragmentary,” Lacovara said. “For example, Sauroposeidon is known from just four neck vertebrae. So, really, who knows?” Meanwhile, Amphicoelias, a sauropod known from only a sketch of a single vertebra in a notebook from the 19th century paleontologist Edward Cope, is sometimes cited as the longest, tallest and heaviest dinosaur.

“The vertebra was apparently lost or destroyed in transport — or maybe never existed,” Lacovara said. “You can’t have a dinosaur represented by nothing, so as far as I’m concerned, Amphicoelias is not a thing.”

As for the tallest dinosaur, the winner is likely Giraffatitan, a 40-foot-tall(12 m) sauropod dinosaur that lived in the late Jurassic about 150 million years ago in what is now Tanzania.

As for that dinosaur’s actual height, the devil is in the details.

“This, of course, depends on whether these animals could lift their necks up to maximum height,” Lacovara said. “Their forelimb and shoulder structure looks like they were angling their necks upward, but we may never know the degree to which they could do this.”

Source:Originally published on Live Science.

@WFS,World Fossil Society,Riffin T Sajeev,Russel T Sajeev