Early Cretaceous Fossil Research Articles

A puzzling frog crab (Crustacea: Decapoda: Brachyura) from the Early Cretaceous Santana Group of Brazil: frog first or crab first?

The evolutionary origin of frog crabs (Raninoida) remains puzzling partly due to their astonishing morphological disparity, ranging from broad and heavily ornamented ‘crab-like’ extinct families (necrocarcinids and allies), to elongate and smoother ‘frog-like’ extant ones (raninids and allies). However, an ancient Cretaceous clade (Palaeocorystidae) displays a combination of plesiomorphic and apomorphic traits that might advocate for either evolutionary scenario: from ‘crab-like’ to ‘frog-like’, or vice versa. This lack of agreement is partly fuelled by the scarcity of Early Cretaceous fossils, a time from which the first raninoidans are known. A close re-examination of an Early Cretaceous fossil from the Santana Group of Brazil, Araripecarcinus ferreirai Martins-Neto, 1987, combined with phylogenetic analysis including all main clades of podotreme crabs, reinforces its raninoidan condition, and rejects the initial hypothesis of a Portunoidea affinity. Furthermore, comparisons with other raninoidans support the hypothesis that a more ‘crab-like’ body plan is the plesiomorphic condition for raninoidans, and that the ‘frog-like’ architecture of Palaeocorystidae, and perhaps the Raninoidea as a whole, reflects a derived condition related to a specialized burrowing lifestyle. Phylogenetic analyses are fundamental to evaluate the position of Palaeocorystidae with respect to raninoidean and necrocarcinid-like families, helping to better resolve the Raninoida evolutionary tree of life, and to gain a broader understanding on their relatedness by common ancestry throughout geological time.

Occurrences of Early Cretaceous fossil woods in China: Implications for paleoclimates

The Chinese Early Cretaceous flora was divided phytogeographically into the Northern Floristic Province and the Southern Floristic Province. The “temperate–wet vegetations” and “tropic–subtropic xeric vegetations” were proposed to represent the two different vegetation types. About 52 species of fossil woods belonging to Cycadophytes (2 species), Ginkgoales (1 species) and coniferales (49 species) have been discovered in the two floristic provinces, mainly from the Northeast China. The biodiversity and anatomical characteristics, especially the growth ring feature analysis of fossil woods indicated climatic conditions with seasonal variation in both the Northern and Southern Floristic Provinces during the Early Cretaceous. It suggests that a tropic to sub-tropic semi-arid climate might dominate over southern China, while warm or temperate, and wet climate prevailed in northern China during the Early Cretaceous. The wood evidence is in accordance with that of the leaf fossils collected from the corresponding formations of the Early Cretaceous in China.

Extinct and extant rove beetles meet in the matrix: Early Cretaceous fossils shed light on the evolution of a hyperdiverse insect lineage (Coleoptera: Staphylinidae: Staphylininae).

Description of the Early Cretaceous (Yixian Formation, China) fauna of Staphylininae and Paederinae rove beetles, and a rigorous (maximum parsimony, maximum likelihood and Bayesian inference) phylogenetic analysis of both extinct and extant taxa resulted in the following discoveries: a stem lineage sister to Staphylininae + Paederinae; a new tribe for Staphylininae, Thayeralinini trib. n.; several extinct species of the extant tribe Arrowinini; extinct basal lineages of the extant tribe Staphylinini; two stem genera of the "Xantholinine-lineage" (Staphylininae); and recovery of Mesostaphylinus in Paederinae with several new species. It is demonstrated that by the Early Cretaceous, Paederinae and Staphylininae were already diversified into groups, some of which now represent extant tribes but not the branches dominating in the modern biota. While the study of the Early Cretaceous rove beetle fauna pushes the estimated divergence time between Paederinae and Staphylininae down into the Jurassic, it also suggests that presently hyperdiverse groups of Staphylininae originated some time later than the Early Cretaceous. In addition to one new tribe, five new genera (Paleothius, Cretoprosopus, Thayeralinus, Paleowinus and Durothorax) and 17 new species are described in Staphylininae, and three new species of Mesostaphylinus are described in Paederinae. Mesostaphylinus fraternus (incertae sedis) is moved to the genus Thayeralinus (Staphylininae).

Evolutionary Voyage of Angiosperm Vessel Structure-Function and Its Significance for Early Angiosperm Success

A hypothesized advantage of the building block of the angiosperm vascular network, the vessel, is often cited as a critical innovation that elevated the competitive abilities of early angiosperms above nonangiosperms during the Cretaceous. Here we synthesize recent discoveries on the hydraulic functions of living basal angiosperm lineages with evidence from the fossil record to trace the early evolutionary significance of vessels in the early ecophysiological radiation of angiosperms. Evidence from extant comparative biology and the Early Cretaceous fossil record of leaves and wood do not support the hypotheses that vessels improved drought tolerance of angiosperms, increased angiosperm’s photosynthetic abilities, or provided an immediate leap in hydraulic capacity. Instead, later tuning of vessel structure for increased flow efficiency—in particular, by the evolution of simple perforation plates—enabled major increases in xylem hydraulic efficiency.

A Reassessment ofKelmayisaurus petrolicus, a Large Theropod Dinosaur from the Early Cretaceous of China

The Early Cretaceous fossil record of large-bodied theropods from Asia is poor, hindering comparison of Asian predatory dinosaur faunas with those from other continents. One of the few large Asian theropod specimens from this interval is a partial skull (maxilla and dentary) from the Lianmugin Formation (?Valanginian—Albian), the holotype of Kelmayisaurus petrolicus. Most authors have either considered this specimen as an indeterminate basal tetanuran or a nomen dubium. We redescribe K. petrolicus and note that it possesses a single autapomorphy (a deep accessory groove on the lateral surface of the anterior dentary), as well as a unique combination of characters that differentiates it from other theropods, affirming its validity. A phylogenetic analysis recovers K. petrolicus as a basal carcharodontosaurid, which is supported by various features: very deep interdental plates (a carcharodontosaurid synapomorphy), fused interdental plates (present in carchardontosaurids and a limited number of other therop...

The oldest fossil species of the rove beetle subfamily Oxyporinae (Coleoptera: Staphylinidae) from the Early Cretaceous (Yixian Formation, China) and its phylogenetic significance

Oxyporus yixianus Solodovnikov & Yue sp. nov., a new Early Cretaceous fossil rove beetle species, is described from the Yixian Formation of Liaoning Province, China. It is clearly placed in Oxyporus Fabricius, 1775, the extant and only genus of the subfamily Oxyporinae. In addition to the hitherto-known, much younger fossils of Oxyporinae, the significantly older age of this newly discovered species makes the currently accepted phylogenetic hypothesis that Oxyporinae is a basal lineage of the Staphylininae group more plausible. The remarkably modern and specialization-rich morphology of Oxyporus yixianus leads to the assumption that this species exemplifies a rather derived stage of divergence of Oxyporinae from the stem of the Staphylininae group. Divergence of Oxyporinae from the rest of the Staphylininae group lineage may have begun significantly earlier than the Early Cretaceous, and the fungus-associated biology of Oxyporinae is also apparently older than documented by Oxyporus yixianus.

A new hypothesis for the origin of the supposed giant snail Dinocochlea from the Wealden of Sussex, England

When first described in 1922, Dinocochlea ingens, an Early Cretaceous (Valanginian) fossil from the Wadhurst Clay Formation (Wealden) of Hastings in Sussex, England, was regarded as the steinkern of a huge gastropod over 2 m in length and claimed to be the largest gastropod ever to have lived. Most subsequent researchers have doubted the identity of D. ingens as a gastropod, usually believing it to be a pseudofossil, but no convincing explanation has been proposed for its origin. Restudy of the type material leads to the new hypothesis that Dinocochlea originated as a horizontal, corkscrew-shaped burrow resembling Helicodromites that acted as a nucleus for concretion growth. Sectioned specimens of Dinocochlea are filled with concentrically banded sediment interpreted to be growth rings of a concretion. Modification of a computer simulation designed to illustrate gastropod shell growth shows how the development of a concretion around a corkscrew-shaped burrow could lead to the morphology seen in Dinocochlea. The most likely tracemaker for Dinocochlea was a capitellid polychaete (‘threadworm’) with a body just a few mm in diameter.

Fossil evidence for low gas exchange capacities for Early Cretaceous angiosperm leaves

The photosynthetic gas exchange capacities of early angiosperms remain enigmatic. Nevertheless, many hypotheses about the causes of early angiosperm success and how angiosperms influenced Mesozoic ecosystem function hinge on understanding the maximum capacity for early angiosperm metabolism. We applied structure-functional analyses of leaf veins and stomatal pore geometry to determine the hydraulic and diffusive gas exchange capacities of Early Cretaceous fossil leaves. All of the late Aptian—early Albian angiosperms measured possessed low vein density and low maximal stomatal pore area, indicating low leaf gas exchange capacities in comparison to modern ecologically dominant angiosperms. Gas exchange capacities for Early Cretaceous angiosperms were equivalent or lower than ferns and gymnosperms. Fossil leaf taxa from Aptian to Paleocene sediments previously identified as putative stem-lineages to Austrobaileyales and Chloranthales had the same gas exchange capacities and possibly leaf water relations of their living relatives. Our results provide fossil evidence for the hypothesis that high leaf gas exchange capacity is a derived feature of later angiosperm evolution. In addition, the leaf gas exchange functions of austrobaileyoid and chloranthoid fossils support the hypothesis that comparative research on the biology of living basal angiosperm lineages reveals genuine signals of Early Cretaceous angiosperm ecophysiology.

Micromorphology of the Seed Envelope ofEphedraL. (Gnetales) and Its Relevance for the Timing of Evolutionary Events

Micromorphology of the seed envelope of Ephedra (Gnetales) is known to be variable, but variation patterns have never been systematically documented. We test the usefulness of this feature for species determination and subclade delimitation in Ephedra and investigate the relationship of this character to infrageneric evolutionary patterns. Most species have a basically smooth seed envelope, which in some species appears slightly striate or reticulate due to convex or depressed outer periclinal cell walls. Ephedra rhytidosperma from China and Ephedra torreyana from North America have transverse lamellae formed by the epidermis. A papillate surface is found in respective close relatives of these two species. Micromorphology of the seed envelope is generally not useful for species identification or subclade delineation. The amount of variation is low, and intraspecific variation, which in some cases seems to be correlated with hybridization and/or introgression, complicates species recognition. Furthermore, parallel evolution of similar micromorphological patterns in unrelated subclades of Ephedra is evident and cannot be explained by similar seed dispersal mechanisms. The Asian species with transverse lamellae or papillae on the seed are dispersed by frugivores whereas similar American species are anemochoric. Transverse ridges occur in several Early Cretaceous fossil seeds with affinity to Ephedra. However, our results indicate that the resemblance between these fossils and extant taxa with similar features is superficial and convergent. In line with other recent studies, we find that Cretaceous ephedroids are extinct stem relatives to the extant clade.

Two Early Cretaceous fishes discovered from the most northern area of China: implications for the palaeobiogeography of the Jehol Biota

AbstractFrom a newly discovered Early Cretaceous fossil site at the Sanlianhe Coal Mine in Tahe County, Heilongjiang Province, the most northern area in China, two freshwater fossil fish had been recovered. This paper reports their classifications and implications regarding the palaeobiogeography of the Jehol Biota. The fish assemblage consists of Yanosteus sp. (Acipenseriforms) and Sinamia sp. (Amiiformes). Both are important members of the well known Jehol Biota, and their occurrence supports the correlation of the Yiliekede Formation at Sanlianhe Coal Mine site with the Jiufotang Formation of West Liaoning. The remains of the Yanosteus sp. from this locality is the first known record of the genus other than in the Yan‐Liao area of China, and the specimens of Sinamia sp. is quite similar to what may be a new species of Sinamia from West Liaoning. The new fossil site represents the most northern site that is undoubtedly part of the extent of the Jehol Biota as currently understood. The northern Great Xing'an Range area is an important region that may link correlations between the Early Cretaceous continental biotas of China, Mongolia and Russia. Copyright © 2010 John Wiley & Sons, Ltd.

The female reproductive unit of Ephedra (Gnetales): comparative morphology and evolutionary perspectives

Morphological variation in Ephedra (Gnetales) is limited and confusing from an evolutionary perspective, with parallelisms and intraspecific variation. However, recent analyses of molecular data provide a phylogenetic framework for investigations of morphological traits, albeit with few informative characters in the investigated gene regions. We document morphological, anatomical and histological variation patterns in the female reproductive unit and test the hypothesis that some Early Cretaceous fossils, which share synapomorphies with Ephedra, are members of the extant clade. Results indicate that some morphological features are evolutionarily informative although intraspecific variation is evident. Histology and anatomy of cone bracts and seed envelopes show clade-specific variation patterns. There is little evidence for an inclusion of the Cretaceous fossils in the extant clade. Rather, a hypothesized general pattern of reduction of the vasculature in the ephedran seed envelope, probably from four vascular bundles in the fossils, to ancestrally three in the living clade, and later to two, is consistent with phylogenetic and temporal analyses, which indicate that extant diversity evolved after the Cretaceous-Tertiary boundary. Notwithstanding striking similarities between living and Cretaceous Ephedra, available data indicate that the Mesozoic diversity went almost entirely extinct in the late Cretaceous causing a bottleneck effect in Ephedra, still reflected today by an extraordinarily low level of genetic and structural diversity.

Integrating Early Cretaceous fossils into the phylogeny of living angiosperms: Magnoliidae and eudicots

Abstract Over the past 25 years, discoveries of Early Cretaceous fossil flowers, often associated with pollen and sometimes with vegetative parts, have revolutionized our understanding of the morphology and diversity of early angiosperms. However, few of these fossils have been integrated into the increasingly robust phylogeny of living angiosperms based primarily on molecular data. To remedy this situation, we have used a morphological dataset for living basal angiosperms (including basal eudicots and monocots) to assess the most parsimonious positions of early angiosperm fossils on cladograms of Recent plants, using constraint trees that represent the current range of hypotheses on higher‐level relationships, and concentrating on Magnoliidae (the clade including Magnoliales, Laurales, Canellales, and Piperales) and eudicots. In magnoliids, our results confirm proposed relationships ofArchaeanthus(latest Albian?) to Magnoliaceae,Endressinia(late Aptian) to Magnoliales (the clade comprisingDegeneria,Galbulimima,Eupomatia, and Annonaceae), andWalkeripollispollen tetrads (late Barremian?) to Winteraceae, but they indicate thatMauldinia(early Cenomanian) was sister to both Lauraceae and Hernandiaceae rather than to Lauraceae alone. Among middle Albian to early Cenomanian eudicots, we confirm relationships ofNelumbitestoNelumbo, platanoid inflorescences andSapindopsisto Platanaceae, andSpanomerato Buxaceae. With the possible exception ofArchaeanthus, these fossils are apparently not crown group members of living families but rather stem relatives of one or more families.

Modern thrips families Thripidae and Phlaeothripidae in Early Cretaceous amber (Insecta: Thysanoptera)

Two specimens of Thysanoptera with forked sensilla on third and fourth antennal segments were described from the Lebanese Neocomian and the Spanish Albian ambers, and attributed to the new genus Tethysthrips n. gen. in the family Thripidae Stevens 1829. One specimen with a tubular tenth abdominal segment was also discovered in the Lebanese Neocomian amber, and attributed to the new genus Rohrthrips n. gen. belonging to the family Phlaeothripidae Uzel 1895. Thripidae and Phlaeothripidae are nowadays the most species-rich families of Thysanoptera. The present discoveries of Early Cretaceous fossils show how diversified these families and thrips already were at that time. Moreover, this tubuliferan Rohrthrips specimen has plesiomorphies no longer present in the recent genera, in particular on the wings. Therefore it brings new insight in the evolution of Tubulifera.

Reconstructing the ancestral angiosperm flower and its initial specializations

Increasingly robust understanding of angiosperm phylogeny allows more secure reconstruction of the flower in the most recent common ancestor of extant angiosperms and its early evolution. The surprising emergence of several extant and fossil taxa with simple flowers near the base of the angiosperms-Chloranthaceae, Ceratophyllum, Hydatellaceae, and the Early Cretaceous fossil Archaefructus (the last three are water plants)-has brought a new twist to this problem. We evaluate early floral evolution in angiosperms by parsimony optimization of morphological characters on phylogenetic trees derived from morphological and molecular data. Our analyses imply that Ceratophyllum may be related to Chloranthaceae, and Archaefructus to either Hydatellaceae or Ceratophyllum. Inferred ancestral features include more than two whorls (or series) of tepals and stamens, stamens with protruding adaxial or lateral pollen sacs, several free, ascidiate carpels closed by secretion, extended stigma, extragynoecial compitum, and one or several ventral pendent ovule(s). The ancestral state in other characters is equivocal: e.g., bisexual vs. unisexual flowers, whorled vs. spiral floral phyllotaxis, presence vs. absence of tepal differentiation, anatropous vs. orthotropous ovules. Our results indicate that the simple flowers of the newly recognized basal groups are reduced rather than primitively simple.

Woody or not woody? Evidence for early angiosperm habit from the Early Cretaceous fossil wood record of Europe

The important question of early angiosperm growth habit (i.e., trees, shrubs or herbs?) remains unanswered. Various theories have been based on data from both living and fossil plants. The Early Cretaceous fossil wood record, however, was seldom used to investigate early angiosperm habit. We set up a database for the Early Cretaceous and Cenomanian of Europe, as this area has the most complete and stratigraphically well-constrained record. The database has 170 entries, based on a bibliographical survey and on the examination of more than 600 new fossil wood specimens from a wide range of palaeoenvironments. In our record the woody characteristic in angiosperms appeared during the Albian, whereas most of the angiosperm's early evolution took place earlier, during the earliest Cretaceous. From the European fossil wood record for the Early Cretaceous and Cenomanian, the global extension and dominance of angiosperms in the Cenomanian is concomitant with a sharp increase in heteroxylous wood diversity. It appears that small stature and weak wood limited the angiosperm ecological radiation for some time.

The oldest platypus and its bearing on divergence timing of the platypus and echidna clades.

Monotremes have left a poor fossil record, and paleontology has been virtually mute during two decades of discussion about molecular clock estimates of the timing of divergence between the platypus and echidna clades. We describe evidence from high-resolution x-ray computed tomography indicating that Teinolophos, an Early Cretaceous fossil from Australia's Flat Rocks locality (121-112.5 Ma), lies within the crown clade Monotremata, as a basal platypus. Strict molecular clock estimates of the divergence between platypus and echidnas range from 17 to 80 Ma, but Teinolophos suggests that the two monotreme clades were already distinct in the Early Cretaceous, and that their divergence may predate even the oldest strict molecular estimates by at least 50%. We generated relaxed molecular clock models using three different data sets, but only one yielded a date overlapping with the age of Teinolophos. Morphology suggests that Teinolophos is a platypus in both phylogenetic and ecological aspects, and tends to contradict the popular view of rapid Cenozoic monotreme diversification. Whereas the monotreme fossil record is still sparse and open to interpretation, the new data are consistent with much slower ecological, morphological, and taxonomic diversification rates for monotremes than in their sister taxon, the therian mammals. This alternative view of a deep geological history for monotremes suggests that rate heterogeneities may have affected mammalian evolution in such a way as to defeat strict molecular clock models and to challenge even relaxed molecular clock models when applied to mammalian history at a deep temporal scale.

Termite borings in Early Cretaceous fossil wood, Isle of Wight, UK

A pellet-filled boring in fossil wood is described from the Early Cretaceous Wessex Formation (Barremian), Isle of Wight. The cylindrical boring, approximately 1 cm in diameter, is filled with carbonaceous pellets with a hexagonal shape, preserved within a matrix of pyrite. Features of the boring suggest that it was made by termites that bored into the wood, either when the tree was alive or in the early stages of decay on the forest floor. This evidence of termite activity complements previous records of termite wing fossils and faecal pellets in Wealden sediments and is evidence for social behaviour in Wealden insects. This is one of the oldest records of termite borings in wood.

Controlled excavations in the Romualdo Member of the Santana Formation (Early Cretaceous, Araripe Basin, northeastern Brazil): stratigraphic, palaeoenvironmental and palaeoecological implications

The Romualdo Member of the Santana Formation (Araripe Basin, northeastern Brazil) is famous for the abundance and the exceptional preservation of the fossils found in its early diagenetic carbonate concretions. However, a vast majority of these Early Cretaceous fossils lack precise geographical and stratigraphic data. The absence of such contextual proxies hinders our understanding of the apparent variations in faunal composition and abundance patterns across the Araripe Basin. We conducted controlled excavations in the Romualdo Member in order to provide a detailed account of its main stratigraphic, sedimentological and palaeontological features near Santana do Cariri, Ceará State. We provide the first fine-scale stratigraphic sequence ever established for the Romualdo Member and we distinguish at least seven concretion-bearing horizons. Notably, a 60-cm-thick group of layers (“Matracão”), located in the middle part of the member, is virtually barren of fossiliferous concretions. Moreover, a sample of 233 concretions shows that (i) the stratigraphic distribution of the concretions is very heterogeneous and their density varies from 0.8 to 15 concretions/m 3; (ii) concretions have a preferential, bimodal orientation pattern (major NW–SE axis and secondary ≈N–S axis) throughout the section, suggestive of permanent palaeocurrents of low energy; (iii) few concretions yield the well-preserved vertebrates that have made the Romualdo Member so famous, and those are mainly restricted to four stratigraphic horizons; (iv) only six fish taxa were recovered, the most common being Vinctifer and Tharrhias, followed by Cladocyclus, whereas Brannerion, Calamopleurus (= Enneles) and Notelops are rare. No tetrapod was found in the sample; (v) there is a strong stratigraphic control in the distribution of these taxa and one can distinguish at least three major assemblages at the same locus. These are, from older to younger, a Tharrhias-dominated assemblage, an assemblage dominated by Tharrhias and by Cladocyclus, and a Vinctifer-dominated assemblage. The stratigraphic sequence of these assemblages also corresponds to their ranking in terms of diversity (richness and evenness); (vi) previous accounts on the taxonomic composition and relative abundance of fossils from the Romualdo Member were severely biased toward well-preserved and exotic fossils. They are therefore inappropriate for drawing palaeoecological inferences. The factors responsible for the variations in faunal composition and abundance patterns across the Araripe Basin remain largely unknown, and we hypothesize that climate and/or palaeogeography might be the major forcing agents. Only fine-scale stratigraphic and palaeontological investigations have the potential to solve this issue. In turn, this work marks the first step of an expanded research program that aims at explaining the spatio-temporal relationships between palaeocommunities and their palaeoenvironment in the Araripe Basin during Aptian/Albian times.

Environmental implications of Gondwana wood studies in India

A synthesis of fossil gymnospermous woods from various Gondwana basins of India is presented, and characters of growth rings in the secondary wood, particularly tracheidal cell characters, are evaluated for possible palaeoclimatic signals. Permian fossil woods are mostly recorded from the Damuda, Wardha and Pranhita-Godavari basins. Growth rings are common in many of these species and suggest strong seasonality. Triassic woods are poorly known from the South Rewa Gondwana Basin; the paucity of growth rings suggests a lack of marked seasons. Available evidence on Jurassic woods from the Pranhita-Godavari Graben indicates lack of consistency in the growth ring distribution. Early Cretaceous fossil woods recorded from the Damuda, Pranhita-Godavari, East-Coast and Kutch basins mostly show growth rings, which suggest prevalence of distinct seasons. Ecological factors coupled with phenotypic plasticity, i.e., variation with the same genotype as a function of environmental differences (genetic flexibility) probably dictated wood accumulation patterns in Indian Gondwana woods. However, palaeo-latitudinal and palaeo-physiographic constraints influenced habitats, and subsequent taphonomic processes resulted in incomplete understanding of palaeoclimate. In the absence of contemporary meteorological data during Gondwana times on what is now on the Indian continent, fossil woods constitute an important tool for understanding the past impact of climate on tree growth.

Biogeographic analysis of Jurassic–Early Cretaceous wood assemblages from Gondwana

The terrestrial biogeography of Gondwana during Jurassic–Early Cretaceous times is poorly resolved, and the flora is usually considered to have been rather uniform. This is surprising given the size of Gondwana, which extended from the equator to the South Pole. Documenting Gondwanan terrestrial floristic provincialism in the Jurassic–Early Cretaceous times is important because it provides a historical biogeographic context in which to understand the tremendous evolutionary radiations that occurred during the mid-Cretaceous. In this paper, the distribution of Jurassic–Early Cretaceous fossil wood is analysed at generic level across the entire supercontinent. Specifically, wood assemblages are analyzed in terms of five climatic zones (summer wet, desert, winter wet, warm temperate, cool temperate) established on the basis of independent data. Results demonstrate that araucarian-like conifer wood was a dominant, cosmopolitan element, whereas other taxa showed a greater degree of provincialism. Indeed, several narrowly endemic morphogenera are recognizable from the data. Finally, comparisons with Laurasian wood assemblages indicate strong parallelism between the vegetation of both hemispheres.