Coral fossils
Coral reef fossils found at great heights in mountain ranges around the world provide a testimony to the dramatic geological changes our planet has undergone over vast spans of time. These ancient marine ecosystems, now preserved in rock, offer a window into environments vastly different from the mountainous landscapes we see today. One of the most striking examples can be found in the Dolomites of northern Italy, towering up to 3,343 meters (10,968 feet) above sea level. Here, within the sedimentary rock formations, lie the fossilized remains of vibrant coral reefs that once thrived in warm, shallow seas supposedly during the Triassic period, over 200 million years ago. The shapes and patterns of the fossilized corals bear witness to the diversity of life that once flourished in these ancient marine environments.
Crossing the Atlantic, we find similar evidence in the Andes Mountains of South America. In regions like Peru and Bolivia, at elevations exceeding 4,000 meters (13,000 feet), fossilized coral reefs dating back supposedly to the Jurassic and Cretaceous periods can be found embedded within the rock layers. These remnants of bygone ecosystems stand in stark contrast to the rugged, arid landscapes that surround them today. In the Himalayas, in regions of Nepal and Tibet, at elevations surpassing 5,000 meters (16,400 feet), fossils of corals, ammonites, and other marine organisms are found in abundance. These fossils provide compelling evidence that the towering peaks we see today were once submerged beneath ancient oceans. Closer to home, the Rocky Mountains of North America also bear the imprint of ancient coral reefs. In areas like the Canadian Rockies and the Bighorn Basin of Wyoming, fossil beds containing well-preserved coral structures offer a glimpse into the vibrant marine ecosystems that once occupied these regions.
The presence of these coral reef fossils at such extreme elevations raises questions about the mechanisms that could have uplifted and exposed these former seabeds. Geologists point to the immense forces of plate tectonics, continental drift, and mountain-building processes as the driving factors behind these dramatic transformations. These ancient coral reefs not only provide insights into Earth's past environments but also serve as powerful reminders of the dynamic nature of our planet. They are living witnesses to the constant cycle of change, where oceans give way to mountains, and landscapes are reshaped by the relentless forces of geology.
Evolutionary Timeline of Fossilized Coral Reefs
While the proposed evolutionary timeline attempts to trace the origins and development of fossilized coral reefs, it is important to recognize the significant gaps and challenges presented by the fossil record itself.
Precambrian Era (4.6 billion - 541 million years ago): The earliest evidence of reef-like structures dates back to the Archean Era, with the appearance of stromatolites formed by microbial communities. However, these structures were not living organisms and lacked the complexity of true coral reefs.
Cambrian Period (541 - 485 million years ago): The first true reef structures emerged during the late Cambrian period, created by small coral-like animals called cloudina. However, the sudden appearance of these complex structures without clear ancestral lineages or transitional forms raises questions about their purported gradual evolution.
Ordovician Period (485 - 444 million years ago): Reef ecosystems continued to diversify, with the appearance of the earliest reef-building corals, such as Lichenaria. However, the fossil record lacks transitional forms connecting these coral species to earlier precursors, challenging the expected gradual development.
Subsequent Periods: Throughout the remaining geological periods, the fossil record reveals numerous instances of rapid diversification, decline, and recovery of coral reef ecosystems. The sudden appearances of new coral species and the lack of transitional forms connecting them to their predecessors pose a significant challenge to the conventional evolutionary narrative.
Challenges and Gaps: An Alternative Perspective
The proposed evolutionary timeline of fossilized coral reefs is riddled with numerous gaps, abrupt appearances, and a lack of transitional forms that undermine the conventional gradualist model of evolution. The sudden emergence of complex reef structures during the Cambrian period, without clear ancestral lineages or transitional fossils, raises doubts about their gradual evolution from simpler forms. Throughout subsequent geological periods, the fossil record lacks transitional forms connecting different coral species, making it difficult to reconstruct their evolutionary pathways. The rapid diversification and decline of coral reefs during certain periods, such as the Ordovician and Permian, lack comprehensive explanations within the evolutionary framework. The recovery of coral reefs after major extinction events, like the Permian-Triassic crisis, is marked by sudden appearances of new species without clear ancestral links. Moreover, the absence of transitional forms connecting modern corals to their fossilized counterparts suggests a discontinuity that challenges the expected smooth transition in evolutionary theory. These numerous gaps, abrupt appearances, and lack of transitional forms indicate that the proposed evolutionary timeline may be incomplete and inadequate in accounting for the observed fossil evidence. An alternative perspective, considering a model of separate creations and catastrophic events, might better explain the sudden appearances, diversifications, and eventual declines or extinctions of these remarkable reef ecosystems. The fossil record, while providing valuable insights into the history of coral reefs, also presents significant challenges to the conventional evolutionary narrative.
Jack Tamisiea (2021) Hakai Fossils From One of the World’s First Reefs Can Be Found on Mountains in Nevada Archaeocyaths were the original reef builders, and one of the best places to see them is in the desert In the mountains of southwestern Nevada, the dark fossilized remnants of extinct archaeocyath reefs dot the tops of the hills. Millions of years ago, these peaks were at the bottom of the sea.
Around 520 million years ago, not long (geologically speaking) after the Cambrian explosion ushered in a sudden abundance of complex life, the tops of these mountains were the seafloor. The Paleozoic sea teemed with invertebrate life, and the organisms living here found refuge in an entirely new kind of ecosystem—an animal-built reef. “This was a major biological innovation, and it was recorded out in California and Nevada,” says Smith, a paleontologist at Johns Hopkins University in Maryland. At a field site roughly eight kilometers northeast of the largely deserted backwater of Gold Point, Nevada—a former mining town with a population of just six people—Smith and her colleagues recently examined the fossilized ruins of one of these ancient reefs. “You’re in the desert walking around on mountains, but at the same time you feel like you’re scuba diving,” Smith says. To the untrained eye, the rocks don’t look like much. But under a microscope, a thin cross-section swarms with shapes resembling segmented donuts and dark, sinuous veins. This abstract motif is the fossilized vestige of the archaeocyaths, a diverse group of filter-feeding sponges. Up close, the rocks in the Nevada desert bristle with the fossilized remains of ancient life. Archaeocyaths were the world’s first reef builders. Common just after the Cambrian explosion, archaeocyaths predate reef-building corals by 40 million years. Like their modern equivalents, archaeocyaths grew on the calcified skeletons of their forebearers, adding their own tubular and branching bodies to build immense structures over generations.
These thriving ecosystems were relatively short-lived. Globally, archaeocyathan reefs only persisted for around 20 million years, a mere blip in oceanic history. It is a mystery why they went extinct, but the Gold Point reef, which offers one of the last known examples of these reef-building sponges, holds a clue. Fossilized archaeocyathan reefs have been found everywhere from Siberia to Morocco. But the reef high up in the mountains of southwestern Nevada is a particular boon to scientists’ understanding of the volatile conditions after the Cambrian explosion. The fossilized reef is 70 meters thick in certain spots, says Sara Pruss, a paleontologist at Massachusetts’ Smith College who was involved in the research. “You can look at the fine-scale changes through time because you get this big, thick period of deposition,” she says. “You can actually see how the environment changes.”
Within the fossilized remains, Pruss and Smith have found evidence of an abrupt change in the climate. By around 515 million years ago, a large slab of ancestral North America known as Laurentia had splintered from a southern supercontinent, spewing massive amounts of carbon into the atmosphere, which siphoned oxygen from the oceans and acidified the water in an event known as the archaeocyath extinction carbon isotope excursion. This event, says Pruss, mirrors how the ocean’s chemistry has changed today, though in a much more dramatic fashion: “There are so many commonalities between the archaeocyath extinction and the decline [of] modern coral reefs,” says Pruss.
The detailed preservation of the Gold Point reef also paints a picture of what it would have looked like in its heyday. The fossils encapsulate a spectrum of coastal habitats and archaeocyath species, from nearshore inhabitants that preferred the wave-battered shallows, to those that could only tolerate quiet deepwater enclaves. This breadth of archaeocyath lifestyles echoes modern-day coral diversity, says Pruss. “If you go to the Bahamas and snorkel around, you see the same [pattern] of different corals living in different places.”
Yet while the Gold Point reef shares structural similarities with a modern coral-encrusted Caribbean key, David Cordie, a paleontologist at Wisconsin’s Edgewood College, says it probably would not have made for great snorkeling. Nearshore and extremely shallow, these reefs would have been swamped by nutrients and sediment washing in from the coasts. “If you were to go back in time, it was probably murky, really shallow, with not nearly as much activity as you might expect in reef environments today,” says Cordie, who was not involved in the new Gold Point research. “So maybe a little underwhelming by some peoples’ standards.”
However, if you could peer through the cloudy water, you would be greeted by an outlandish group of reef inhabitants. Spiny trilobites scuttled along the seafloor, swerving around the featherlike arms of crinoids and cactus-like stalks of chancelloriids, an enigmatic group of sessile creatures encased in hundreds of star-shaped plates of armor. Other excavations nearby have yielded fossilized hyoliths, a bizarre group of ancient brachiopods seemingly ripped from the pages of a science fiction novel. Some hyolith species propped themselves up on the seafloor using a pair of long spines and deployed a roving set of tentacles between their two shells—the lower of which tapered off into a cone—to gather planktonic prey. (Their fossils look a little like an ice cream cone with arms.) Like their modern analogs, archaeocyathan reefs “were hubs of diversity,” says Smith. And the Gold Point reef’s wonderful preservation—which includes its complex three-dimensional structure—has allowed the paleontologists to pinpoint the nooks and crannies where trilobites and early crinoids hunkered down between the stalks of sponges. “You really get a sense of the little houses that things lived in,” says Mary Lonsdale, a graduate student pursuing her doctorate in Smith’s lab at Johns Hopkins. “It’s a thriving ecosystem.” “Reefs are incredible places of diversity, and they’re quite beautiful,” Lonsdale says. “Reef environments are just delightful in the modern world—but they are equally as delightful in the past.” This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com. Link
Morphology: The archaeocyaths had a unique body plan resembling a pair of porous, cone-shaped or dunce hat-like structures, one inside the other, forming inner and outer walls. The space between these calcareous walls is called the intervallum. Both the inner and outer walls were perforated with pores, and the two walls were joined by radially arranged partitions called septae, which looked quite similar to those found in modern corals. While the inverted conical shape was common, archaeocyaths could also have cylindrical or even discoid shapes. Their sizes varied, typically ranging from 1 - 2.5 cm in diameter and 8-15 cm in height, but giant species up to 30 cm tall and about 60 cm in diameter have also been found.
Exoskeleton and Outer Wall: The archaeocyath skeleton was calcareous, composed of either a high-magnesium calcite or extensively recrystallized, dolomitized (magnesium substituted for some calcium), or silicified during fossilization. The inner and outer walls were both extensively perforated by pores, with the pores in the outer wall typically smaller, similar to sponges. The outer wall could also have outgrowths like branches (tersoid) or anchors (rhizoid) attached to the substrate.
Intervallum: The intervallum, the space between the inner and outer walls, was partitioned by thin walls called septae into hundreds of tiny, featureless compartments called loculi, resembling an apartment complex. Transverse (horizontal) walls, if present, were called tabulae. These internal partitions were less porous than the walls and sometimes lacked pores altogether. Other structures occasionally found in this region included upwardly curved domed plates called dissepiments or vesicles, which lacked pores and likely functioned as structural framing.
Inner Wall and Central Cavity: The inner wall often had larger pores, similar to the openings into the spongocoel of conventional sponges. The vesicles could extend into the central cavity, which was open to the environment at the top, with a diameter of 1-5 cm at the wide end and narrowing to a rounded base. The entire system was attached to the substrate through a structure of uncertain composition called the epithecum.
Functional Morphology: The current understanding is that archaeocyaths processed seawater in a manner similar to other sponges. Water entered through the pores in the outer wall, bacteria and detritus were absorbed by specialized cells (choanocytes or equivalent) as the water flowed through the intervallum, and waste was discharged through the central cavity.
Coral reef fossils found at great heights in mountain ranges around the world provide a testimony to the dramatic geological changes our planet has undergone over vast spans of time. These ancient marine ecosystems, now preserved in rock, offer a window into environments vastly different from the mountainous landscapes we see today. One of the most striking examples can be found in the Dolomites of northern Italy, towering up to 3,343 meters (10,968 feet) above sea level. Here, within the sedimentary rock formations, lie the fossilized remains of vibrant coral reefs that once thrived in warm, shallow seas supposedly during the Triassic period, over 200 million years ago. The shapes and patterns of the fossilized corals bear witness to the diversity of life that once flourished in these ancient marine environments.
Crossing the Atlantic, we find similar evidence in the Andes Mountains of South America. In regions like Peru and Bolivia, at elevations exceeding 4,000 meters (13,000 feet), fossilized coral reefs dating back supposedly to the Jurassic and Cretaceous periods can be found embedded within the rock layers. These remnants of bygone ecosystems stand in stark contrast to the rugged, arid landscapes that surround them today. In the Himalayas, in regions of Nepal and Tibet, at elevations surpassing 5,000 meters (16,400 feet), fossils of corals, ammonites, and other marine organisms are found in abundance. These fossils provide compelling evidence that the towering peaks we see today were once submerged beneath ancient oceans. Closer to home, the Rocky Mountains of North America also bear the imprint of ancient coral reefs. In areas like the Canadian Rockies and the Bighorn Basin of Wyoming, fossil beds containing well-preserved coral structures offer a glimpse into the vibrant marine ecosystems that once occupied these regions.
The presence of these coral reef fossils at such extreme elevations raises questions about the mechanisms that could have uplifted and exposed these former seabeds. Geologists point to the immense forces of plate tectonics, continental drift, and mountain-building processes as the driving factors behind these dramatic transformations. These ancient coral reefs not only provide insights into Earth's past environments but also serve as powerful reminders of the dynamic nature of our planet. They are living witnesses to the constant cycle of change, where oceans give way to mountains, and landscapes are reshaped by the relentless forces of geology.
Evolutionary Timeline of Fossilized Coral Reefs
While the proposed evolutionary timeline attempts to trace the origins and development of fossilized coral reefs, it is important to recognize the significant gaps and challenges presented by the fossil record itself.
Precambrian Era (4.6 billion - 541 million years ago): The earliest evidence of reef-like structures dates back to the Archean Era, with the appearance of stromatolites formed by microbial communities. However, these structures were not living organisms and lacked the complexity of true coral reefs.
Cambrian Period (541 - 485 million years ago): The first true reef structures emerged during the late Cambrian period, created by small coral-like animals called cloudina. However, the sudden appearance of these complex structures without clear ancestral lineages or transitional forms raises questions about their purported gradual evolution.
Ordovician Period (485 - 444 million years ago): Reef ecosystems continued to diversify, with the appearance of the earliest reef-building corals, such as Lichenaria. However, the fossil record lacks transitional forms connecting these coral species to earlier precursors, challenging the expected gradual development.
Subsequent Periods: Throughout the remaining geological periods, the fossil record reveals numerous instances of rapid diversification, decline, and recovery of coral reef ecosystems. The sudden appearances of new coral species and the lack of transitional forms connecting them to their predecessors pose a significant challenge to the conventional evolutionary narrative.
Challenges and Gaps: An Alternative Perspective
The proposed evolutionary timeline of fossilized coral reefs is riddled with numerous gaps, abrupt appearances, and a lack of transitional forms that undermine the conventional gradualist model of evolution. The sudden emergence of complex reef structures during the Cambrian period, without clear ancestral lineages or transitional fossils, raises doubts about their gradual evolution from simpler forms. Throughout subsequent geological periods, the fossil record lacks transitional forms connecting different coral species, making it difficult to reconstruct their evolutionary pathways. The rapid diversification and decline of coral reefs during certain periods, such as the Ordovician and Permian, lack comprehensive explanations within the evolutionary framework. The recovery of coral reefs after major extinction events, like the Permian-Triassic crisis, is marked by sudden appearances of new species without clear ancestral links. Moreover, the absence of transitional forms connecting modern corals to their fossilized counterparts suggests a discontinuity that challenges the expected smooth transition in evolutionary theory. These numerous gaps, abrupt appearances, and lack of transitional forms indicate that the proposed evolutionary timeline may be incomplete and inadequate in accounting for the observed fossil evidence. An alternative perspective, considering a model of separate creations and catastrophic events, might better explain the sudden appearances, diversifications, and eventual declines or extinctions of these remarkable reef ecosystems. The fossil record, while providing valuable insights into the history of coral reefs, also presents significant challenges to the conventional evolutionary narrative.
Jack Tamisiea (2021) Hakai Fossils From One of the World’s First Reefs Can Be Found on Mountains in Nevada Archaeocyaths were the original reef builders, and one of the best places to see them is in the desert In the mountains of southwestern Nevada, the dark fossilized remnants of extinct archaeocyath reefs dot the tops of the hills. Millions of years ago, these peaks were at the bottom of the sea.
Around 520 million years ago, not long (geologically speaking) after the Cambrian explosion ushered in a sudden abundance of complex life, the tops of these mountains were the seafloor. The Paleozoic sea teemed with invertebrate life, and the organisms living here found refuge in an entirely new kind of ecosystem—an animal-built reef. “This was a major biological innovation, and it was recorded out in California and Nevada,” says Smith, a paleontologist at Johns Hopkins University in Maryland. At a field site roughly eight kilometers northeast of the largely deserted backwater of Gold Point, Nevada—a former mining town with a population of just six people—Smith and her colleagues recently examined the fossilized ruins of one of these ancient reefs. “You’re in the desert walking around on mountains, but at the same time you feel like you’re scuba diving,” Smith says. To the untrained eye, the rocks don’t look like much. But under a microscope, a thin cross-section swarms with shapes resembling segmented donuts and dark, sinuous veins. This abstract motif is the fossilized vestige of the archaeocyaths, a diverse group of filter-feeding sponges. Up close, the rocks in the Nevada desert bristle with the fossilized remains of ancient life. Archaeocyaths were the world’s first reef builders. Common just after the Cambrian explosion, archaeocyaths predate reef-building corals by 40 million years. Like their modern equivalents, archaeocyaths grew on the calcified skeletons of their forebearers, adding their own tubular and branching bodies to build immense structures over generations.
These thriving ecosystems were relatively short-lived. Globally, archaeocyathan reefs only persisted for around 20 million years, a mere blip in oceanic history. It is a mystery why they went extinct, but the Gold Point reef, which offers one of the last known examples of these reef-building sponges, holds a clue. Fossilized archaeocyathan reefs have been found everywhere from Siberia to Morocco. But the reef high up in the mountains of southwestern Nevada is a particular boon to scientists’ understanding of the volatile conditions after the Cambrian explosion. The fossilized reef is 70 meters thick in certain spots, says Sara Pruss, a paleontologist at Massachusetts’ Smith College who was involved in the research. “You can look at the fine-scale changes through time because you get this big, thick period of deposition,” she says. “You can actually see how the environment changes.”
Within the fossilized remains, Pruss and Smith have found evidence of an abrupt change in the climate. By around 515 million years ago, a large slab of ancestral North America known as Laurentia had splintered from a southern supercontinent, spewing massive amounts of carbon into the atmosphere, which siphoned oxygen from the oceans and acidified the water in an event known as the archaeocyath extinction carbon isotope excursion. This event, says Pruss, mirrors how the ocean’s chemistry has changed today, though in a much more dramatic fashion: “There are so many commonalities between the archaeocyath extinction and the decline [of] modern coral reefs,” says Pruss.
The detailed preservation of the Gold Point reef also paints a picture of what it would have looked like in its heyday. The fossils encapsulate a spectrum of coastal habitats and archaeocyath species, from nearshore inhabitants that preferred the wave-battered shallows, to those that could only tolerate quiet deepwater enclaves. This breadth of archaeocyath lifestyles echoes modern-day coral diversity, says Pruss. “If you go to the Bahamas and snorkel around, you see the same [pattern] of different corals living in different places.”
Yet while the Gold Point reef shares structural similarities with a modern coral-encrusted Caribbean key, David Cordie, a paleontologist at Wisconsin’s Edgewood College, says it probably would not have made for great snorkeling. Nearshore and extremely shallow, these reefs would have been swamped by nutrients and sediment washing in from the coasts. “If you were to go back in time, it was probably murky, really shallow, with not nearly as much activity as you might expect in reef environments today,” says Cordie, who was not involved in the new Gold Point research. “So maybe a little underwhelming by some peoples’ standards.”
However, if you could peer through the cloudy water, you would be greeted by an outlandish group of reef inhabitants. Spiny trilobites scuttled along the seafloor, swerving around the featherlike arms of crinoids and cactus-like stalks of chancelloriids, an enigmatic group of sessile creatures encased in hundreds of star-shaped plates of armor. Other excavations nearby have yielded fossilized hyoliths, a bizarre group of ancient brachiopods seemingly ripped from the pages of a science fiction novel. Some hyolith species propped themselves up on the seafloor using a pair of long spines and deployed a roving set of tentacles between their two shells—the lower of which tapered off into a cone—to gather planktonic prey. (Their fossils look a little like an ice cream cone with arms.) Like their modern analogs, archaeocyathan reefs “were hubs of diversity,” says Smith. And the Gold Point reef’s wonderful preservation—which includes its complex three-dimensional structure—has allowed the paleontologists to pinpoint the nooks and crannies where trilobites and early crinoids hunkered down between the stalks of sponges. “You really get a sense of the little houses that things lived in,” says Mary Lonsdale, a graduate student pursuing her doctorate in Smith’s lab at Johns Hopkins. “It’s a thriving ecosystem.” “Reefs are incredible places of diversity, and they’re quite beautiful,” Lonsdale says. “Reef environments are just delightful in the modern world—but they are equally as delightful in the past.” This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com. Link
Morphology: The archaeocyaths had a unique body plan resembling a pair of porous, cone-shaped or dunce hat-like structures, one inside the other, forming inner and outer walls. The space between these calcareous walls is called the intervallum. Both the inner and outer walls were perforated with pores, and the two walls were joined by radially arranged partitions called septae, which looked quite similar to those found in modern corals. While the inverted conical shape was common, archaeocyaths could also have cylindrical or even discoid shapes. Their sizes varied, typically ranging from 1 - 2.5 cm in diameter and 8-15 cm in height, but giant species up to 30 cm tall and about 60 cm in diameter have also been found.
Exoskeleton and Outer Wall: The archaeocyath skeleton was calcareous, composed of either a high-magnesium calcite or extensively recrystallized, dolomitized (magnesium substituted for some calcium), or silicified during fossilization. The inner and outer walls were both extensively perforated by pores, with the pores in the outer wall typically smaller, similar to sponges. The outer wall could also have outgrowths like branches (tersoid) or anchors (rhizoid) attached to the substrate.
Intervallum: The intervallum, the space between the inner and outer walls, was partitioned by thin walls called septae into hundreds of tiny, featureless compartments called loculi, resembling an apartment complex. Transverse (horizontal) walls, if present, were called tabulae. These internal partitions were less porous than the walls and sometimes lacked pores altogether. Other structures occasionally found in this region included upwardly curved domed plates called dissepiments or vesicles, which lacked pores and likely functioned as structural framing.
Inner Wall and Central Cavity: The inner wall often had larger pores, similar to the openings into the spongocoel of conventional sponges. The vesicles could extend into the central cavity, which was open to the environment at the top, with a diameter of 1-5 cm at the wide end and narrowing to a rounded base. The entire system was attached to the substrate through a structure of uncertain composition called the epithecum.
Functional Morphology: The current understanding is that archaeocyaths processed seawater in a manner similar to other sponges. Water entered through the pores in the outer wall, bacteria and detritus were absorbed by specialized cells (choanocytes or equivalent) as the water flowed through the intervallum, and waste was discharged through the central cavity.
