Illustration and content by Will Sillin show all
Click the animals and plants in the picture to identify them and learn more about them. It is the end of a day in the late Triassic. The last rays of the sun rake across the landscape, silhouetting the plants and animals to the northwest on our right and illuminating the landscape and storm clouds to the southeast, on our left. We are looking south/southwest down the rift valley. Beyond the horizon lies the giant rift valley creating a home for a new ocean, the Atlantic.
Terrestrisuchus: Batrachopus footprints are attributed to early long-legged terrestrial crocodilians. We see one here picking its way through the maze of larger predators. Eastern United States remains are inconclusive in terms of assigning a specific genus. Under the direction of paleontologist Paul Olsen, this proto-crocodilian displays the svelte body of Terrestrisuchus and the more robust head of Protosuchus.
Coelophysis: This graceful predator is the blueprint for one of the most enduring and successful body plans throughout the history of vertebrate life: the theropod. While bipedal predatory dinosaurs would be be at the top of the terrestrial food chain for more than 140 million years, these Grallator tracks made by Coelophysis won't last long. The bar is composed of saturated sand. As Coelophysis' feet press through the surface, water will flow into the depression collapsing the sides of the print and filling it with sediment. Based on the range of sizes of Grallator tracks, paleontologist Walter Coombs thought predators having the proportions of Coelophysis could have ranged in size from a few feet long up to 20 feet long. Coelophysis was about nine feet long. The Coelophysis snout had a kinked tip which Gregory Paul thinks would have been useful for picking up small prey. Coelophysis has just nabbed a small meal by the head. It is still alive and its writhing body hangs from the tip of the Coelophysis' jaw.
Hypsognathus: A wonderfully ornate reptile that tried its best to remain inconspicuous is seen on and near the logs on the lower right. It was likely herbivorous. It a had a 'third eye' on top of its head that functioned as a light sensor. Its skull bristled with spikes. Paleontologist Paul Olsen emphasized that reconstructions of Hypsognathus have incorrectly shown it having the broad and flattened build, like a horned toad. Here we see Hypsognathus with a 'boxier' build and with its the stomach off the ground. A second Hypsognathus has been basking in the sun and is lucky that Coelophysis already has his mouth full. Hypsognathus belonged to the Procolophonidae, a widespread and successful Triassic family historically associated with the ancestors of turtles.
Ornithopod : The trackmaker of Atreipus were probably creatures like these two small ornithopods. Paleontologist Paul Olsen recognized small dimple-like impressions associated with the tridactyl tracks and concluded they were made by the hands. The appearance of the dimples suggests that hands looked like mitts, similar to those of their successors, the iguanodons and hadrosaurs. The dimples also suggest that this early ornithopod could alternate between bipedal and quadrupedal gaits. It is shown with cheeks that allowed it to chew its food to aid digestion. Because we only have tracks to indicate the presence of early ornithopods, those pictured here do not represent a specific genus.
Ornithopod: The trackmaker of Atreipus were probably creatures like these two small ornithopods. Paleontologist Paul Olsen recognized small dimple like impressions associated with the tridactyl tracks and concluded they were made by the hands. The appearance of the dimples suggests that hands looked like mitts, similar to those of their successors, the iguanodons and the hadrosaurs. The dimples also suggest that this early ornithopod could alternate between a bipedal and quadrupedal gait. It is shown with cheeks which allowed it to chew its food and aid digestion. Because we only have tracks to indicate the presence of early ornithopods those pictured here do not represent a specific genus.
Macrotaeniopteris magnifolia: This plant is only known from its leaves (foliage taxon) and has usually been reconstructed as an aquatic fernlike plant or as foliage arranged radially around the top of a thick cycad-type trunk. Some Macrotaeniopteris leaves were eventually classified as belonging to the Bennettitales, an extinct Mesozoic order also known as the Cycadeoideales because of superficial similarities with Cycads. The growth habit of the Cretaceous Cycadeoideales does resemble the thick, unbranched stems of Cycads. There is evidence, though, that the growth habit of early Mesozoic Bennettitalians, like Macrotaeniopteris, were slender and branching. Bruce Cornet suggested using Mountain Laurel as a model to show this alternate reconstruction for Macrotaeniopteris.
Sanmiguelia lewisii: First known from the southwest, this fossil plant was identified by paleobotanist Bruce Cornet in lower Carnian deposits in Virginia. Some of those specimens had previously been misidentified as Neocalamites stem impressions. Cornet argued, based on material he found in Texas, that Sanmiguelia was a primitive angiosperm and the earliest known flowering plant. Though not yet accepted as a flowering plant, it remains a candidate until it is better understood. It is depicted as a semiaquatic plant that resembles extant Veratrum (Green Hellebore).
Podozamites: Podozamites is known only by its leaves (foliage taxon) and was first classed with the Mesozoic cycads. Under the direction of paleobotanist Bruce Cornet and revised classification it is shown here as a conifer with the overall form a Bald Cypress or Dawn Redwood. The environmentally stressed Podozamites tree on the right has grown on an island being buried under sediment and water as the basin floor drops in the growing rift valley. Podozamites leaf litter lies in the right foreground.
Neocalamites: A challenge to classification, Neocalamites is thought to be transitional between 2 families, the Equisetaceae, including living Horsetails, and the Calamitaceae, the tree sized Sphenophytes of the Carboniferous. Although smaller than Calamites, Neocalamites specimens from the American west reached heights of 30 feet. Eastern U.S. specimens are smaller but easily reached heights of 10 feet. It's habitat was along the margins of streams, lakes and wetlands. Neocalamites disappeared from the fossil record in the mid Jurassic.
Pekinopteris: This fern has well know morphology from Carnian fossils in North Carolina. The fronds sprouted from a spreading interconnected root system and new leaves coiled like those of ferns. Until recently it was unclassifiable because of a lack of fertile material. However recent investigations have placed Pekinopteris into the Schizaeacae, a family of ferns with several living tropical and subtropical genera.
Clathropteris: This fern is one of the few plants well represented in the Connecticut valley and is assigned to the family Dipteridaceae. Living Dipteridaceae occur in Malaysia and the Philippines. Like its living relatives, Clathropteris fronds could be as large as an umbrella and hung in a similar fashion. Clathropteris leaves were thicker and tougher than we are accustomed to seeing in a fern and so were better preserved as fossils. It has been found in numerous countries in both the northern and southern hemispheres in Triassic and Jurassic strata. It is thought to have been a pioneer species that would colonize freshly exposed habitats.
Equisitites: Well known from abundant fossils worldwide, Equisitites is similar in appearence to the extant Equisetum (Horsetails). Besides the Equisitites shown in the center foreground there are Equisitites meadows colonizing open gravel bars beyond the water on the right. There were no grasses in the late Triassic, so open areas would have been invaded by plants like Equisitites, which reproduce by spores, not seeds. Equisetum spread rapidly to create extensive Horsetail meadows around Mt. St. Helens after its major eruption in 1980.
Cladophlebis: This name is applied to a type of fern frond (foliage taxon) and not to a specific complete fossil fern. Cladophlebis fronds bearing sporangia are named Todites. Cladophlebis and Todites foliage are prevalent throughout the Mesozoic. Besides the arborescent example of Cladophlebis fronds, it is also depicted as a ground fern. It appears in both forms behind the Coelophysis and as a fern meadow on the island on our left. Many different living ferns have foliage that are similar to Cladophlebis. The Cinnamon fern and the Interrupted fern are two common northeastern US ferns with Cladophlebis type fronds.
Sphenobaiera: Known only from leaves or leaf fragments, Sphenobaiera is a ‘foliage taxon’. Because Sphenobaiera leaves divided in a binary fashion to form deeply dissected fans with an overall shape and pattern of veins similar to Ginkgo leaves, good specimens are tentatively assigned to the Ginkgophytes. Sphenobaiera leaves could be much larger than the extant Ginkgo, some reaching a foot in length. Sphenobaiera first appeared in the Permian and persisted into the early Cretaceous. Paleobotanist Bruce Cornet envisioned a tree bearing Sphenobaiera leaves to have the branching pattern of a modern Ginkgo, but foliage hanging like that of a Willow. To the right of the mature Sphenobaiera tree is a younger specimen. Sphenobaiera leaf litter is also shown on the ground to the right of Coelophysis.
Rutiodon: The tracks known as Apatopus are attributed to the Phytosaur, Rutiodon. Rutiodons occupied the same niche that Crocodilians occupy today, living mostly in water and feeding on fish. They also likely preyed on terrestrial animals that frequented the river banks. The nares were positioned back on the head just in front of the eyes rather than at the tip of spout as in Crocodilians. The gait shown is semi-erect with the body raised slightly off the ground. The arms and legs, however, do not pivot under the body to a vertical position as is seen in the "high walk" of crocodiles. Phytosaurs disappeared with the Triassic/Jurassic extinction.
Rutiodon: A dead Rutiodon is trapped in a snag having been torn open by scavengers.
Sphenodontid: Though the Sphenodontids were a successful and wide spread Mesozoic family who left tracks called Rhynchosauroides, there was no direct evidence of their presence in the Hartford Basin when this paleo reconstruction was completed in 1991. In 1993 Hans Dieter Sues and Donald Baird discovered a Sphenodontian skull in the Triassic New Haven Arkose, providing the first direct evidence for its presence in the Hartford and Deerfield Basins. Today, the Sphenodontids are represented by a single species, the "living fossil" Sphenodon (Tuatara), that lives on a few small islands off the New Zealand coast. A Sphenodontid, struggling to free itself, dangles from the jaws of Coelophysis.
Rutiodon: Two more Rutiodons conserve their energy at the end of the bar near the center of the view. The one facing us head-on shows Rutiodon's high, narrow cross section. Rutiodons had long neural spines. During hot days, perhaps Rutiodons spent time moderating their temperature in the river and catching fish. These Rutiodons are hauling out at the end of the day as temperatures cooled, and running off the other animals that may have emerged from the shadows for a late-afternoon drink and bite to eat.
Stegomus: Known from skeletal remains found in Connecticut and possibly the maker of Chirotherium tracks, the heavily armored adult Stegomus grew to be five feet long. Stegomus belonged to the order Aetosauria. Aetosaurs were limited to the Late Triassic, yet their remains have been found on every continent except Antarctica. They are considered close relatives of early Crocodillians. Paleontologist Donald Baird believed Stegomus was herbivorous or perhaps omnivorous. Its toothless snout would have been good for rooting in the mud. Perhaps it ate insect larvae, grubs, freshwater clams, and crayfish. We see an adult Stegomus tearing a fern out of the ground. Would he eat the plant? Or was he looking for small prey hiding in the roots?
Rutiodon: Two more Rutiodons conserve their energy at the end of the bar near the center of the view. The one facing us head on shows Rutiodon's high narrow cross section. Rutiodon had long neural spines. During hot days perhaps Rutiodons spent time moderating their temperature in the river and catching fish. These Rutiodons are hauling out at the end of the day as temperatures cooled and running off the other animals that may have emerged from the shadows for a late afternoon drink and bite to eat.